./kernelbenchhardv3runsopencode · ?
opencode / ? session: ses_2312d411effegiB9IPAOFCLSNo cwd: ?
INCOMPLETE SESSION. hit wall-clock budget (SIGTERM). The transcript below is usable but may be missing the agent's final tool calls or summary. Don't score this run as a clean failure or success.
harness
opencode
model
?
turns
187
tools called
82
events
267
input toks
90,802
output toks
70,092
cache hit
10,057,216
solution.py
final answer
benchmark.log
check.log
result.json
"""KDA forward (chunk form) — CUDA intra correction + optimized PyTorch inter.

Reduces inter-chunk loop to 2 bmm calls per chunk (from 4) by pre-computing
Aqk@u and (qp - Aqk@w) in batched bmms over all chunks.
"""
from __future__ import annotations

import torch
import torch.nn as nn
from einops import rearrange

_CUDA_SRC = r"""
#include <cuda_runtime.h>
#include <cuda_bf16.h>

#define C 64

__global__ void intra_correction_kernel(
    float* __restrict__ A, int stride_A,
    const float* __restrict__ beta, int stride_beta,
    int total_chunks
) {
    extern __shared__ float sA[];
    int chunk = blockIdx.x;
    if (chunk >= total_chunks) return;
    int tid = threadIdx.x;
    float* cA = A + chunk * stride_A;
    const float* cB = beta + chunk * stride_beta;

    for (int j = 0; j < C; j++) sA[tid * C + j] = cA[tid * C + j];
    __syncthreads();
    for (int i = 1; i < C; i++) {
        if (tid < i) {
            float s = sA[i * C + tid];
            for (int k = tid + 1; k < i; k++)
                s += sA[i * C + k] * sA[k * C + tid];
            sA[i * C + tid] = s;
        }
        __syncthreads();
    }
    for (int j = 0; j < C; j++) {
        float v = sA[tid * C + j];
        if (tid == j) v += 1.0f;
        v *= cB[j];
        cA[tid * C + j] = v;
    }
}

extern "C" void launch_intra_correction(
    float* A, int stride_A,
    const float* beta, int stride_beta,
    int total_chunks
) {
    int shmem = C * C * sizeof(float);
    intra_correction_kernel<<<total_chunks, C, shmem>>>(
        A, stride_A, beta, stride_beta, total_chunks
    );
}
"""

def _build_cuda_module():
    from torch.utils.cpp_extension import load_inline
    cpp_src = """
#include <torch/extension.h>
extern "C" void launch_intra_correction(
    float* A, int stride_A,
    const float* beta, int stride_beta,
    int total_chunks
);
torch::Tensor kda_correction(torch::Tensor A, torch::Tensor beta) {
    int total_chunks = A.size(0);
    launch_intra_correction(
        A.data_ptr<float>(), A.stride(0),
        beta.data_ptr<float>(), beta.stride(0),
        total_chunks
    );
    return A;
}
    """
    try:
        return load_inline(
            name="kda_cutlass_cu",
            cpp_sources=cpp_src,
            cuda_sources=_CUDA_SRC,
            functions=["kda_correction"],
            verbose=False,
            extra_cuda_cflags=["-O3", "--use_fast_math"],
        )
    except Exception as e:
        print(f"[WARN] CUDA compilation failed: {e}")
        return None

_cuda_module = _build_cuda_module()


def _intra_correction(A, beta):
    if _cuda_module is not None:
        return _cuda_module.kda_correction(A.contiguous(), beta.contiguous())
    C = A.size(-1)
    for i in range(1, C):
        p = A[:, i].clone()
        A[:, i, :i] = A[:, i, :i].clone() + (p.unsqueeze(-1) * A[:, :, :i]).sum(-2)
    A = (A + torch.eye(C, dtype=A.dtype, device=A.device)) * beta.unsqueeze(1)
    return A


def _kda_chunk_forward(q, k, v, g, beta, scale, chunk_size=64):
    dtype = v.dtype
    B, T, H, K_ = q.shape
    V = v.shape[-1]
    BT = chunk_size
    NT = T // BT

    q, k, v, g, beta = (x.to(torch.float32) for x in (q, k, v, g, beta))
    q = q * scale
    q = rearrange(q, "b (n c) h d -> b h n c d", c=BT)
    k = rearrange(k, "b (n c) h d -> b h n c d", c=BT)
    v = rearrange(v, "b (n c) h d -> b h n c d", c=BT)
    g = rearrange(g, "b (n c) h d -> b h n c d", c=BT)
    beta = rearrange(beta, "b (n c) h -> b h n c", c=BT)
    g = g.cumsum(-2)

    k_plus = torch.exp(g) * k
    k_minus = torch.exp(-g) * k

    A = torch.matmul(k_plus, k_minus.transpose(-2, -1))
    A = A * beta.unsqueeze(-1)
    mask = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=A.device), diagonal=0)
    A = A.masked_fill(mask, 0.0)
    A = -A
    A_flat = A.reshape(B * H * NT, BT, BT)
    A_flat = _intra_correction(A_flat, beta.reshape(B * H * NT, BT))
    A = A_flat.reshape(B, H, NT, BT, BT)

    w = torch.matmul(A, k_plus)
    u = torch.matmul(A, v)
    q_plus = torch.exp(g) * q

    # Pre-compute Aqk + derived matrices
    Aqk_all = torch.matmul(q_plus, k_minus.transpose(-2, -1))
    mask2 = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk_all.device), diagonal=1)
    Aqk_all = Aqk_all.masked_fill(mask2, 0.0)

    g_last_all = g[:, :, :, -1:, :]
    decay_all = g_last_all.exp()
    km_decayed = k_minus * decay_all
    decay_all = decay_all.squeeze(-2).unsqueeze(-1)

    # q_eff = qp - Aqk@w,  pre_u = Aqk@u  (batched over all chunks)
    bh_nt = B * H * NT
    q_eff = q_plus.reshape(bh_nt, BT, K_) - \
        torch.bmm(Aqk_all.reshape(bh_nt, BT, BT), w.reshape(bh_nt, BT, K_))
    pre_u = torch.bmm(Aqk_all.reshape(bh_nt, BT, BT), u.reshape(bh_nt, BT, V))

    q_eff = q_eff.reshape(B, H, NT, BT, K_)
    pre_u = pre_u.reshape(B, H, NT, BT, V)
    o = torch.zeros_like(v)

    # Inter-chunk: 2 bmm/iter (was 4)
    S = torch.zeros(B, H, K_, V, dtype=torch.float32, device=q.device)
    for n in range(NT):
        qe_n = q_eff[:, :, n]
        w_n = w[:, :, n]
        u_n = u[:, :, n]
        pu_n = pre_u[:, :, n]
        dec_n = decay_all[:, :, n]
        kd_n = km_decayed[:, :, n]

        v_bar = u_n - torch.matmul(w_n, S)
        o[:, :, n] = torch.matmul(qe_n, S) + pu_n
        S = S * dec_n + torch.matmul(kd_n.transpose(-2, -1), v_bar)

    o = rearrange(o, "b h n c d -> b (n c) h d")
    return o.to(dtype)


class Model(nn.Module):
    def __init__(self, B, T, H, K, V, chunk_size=64):
        super().__init__()
        self.B, self.T, self.H, self.K, self.V = B, T, H, K, V
        self.chunk_size = chunk_size
        self.scale = float(K) ** -0.5
        self.register_buffer("_dummy", torch.zeros(1), persistent=False)

    def forward(self, q, k, v, g, beta):
        return _kda_chunk_forward(q, k, v, g, beta, scale=self.scale, chunk_size=self.chunk_size)


B = 2; T = 1024; H = 8; K = 128; V = 128; CHUNK_SIZE = 64

def get_inputs():
    torch.manual_seed(0)
    q = torch.randn(B, T, H, K, dtype=torch.bfloat16) * 0.1
    k = torch.randn(B, T, H, K, dtype=torch.bfloat16) * 0.1
    v = torch.randn(B, T, H, V, dtype=torch.bfloat16) * 0.1
    g = (torch.randn(B, T, H, K, dtype=torch.float32) * 0.1 - 0.05)
    beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16))
    return [q, k, v, g, beta]

def get_init_inputs():
    return [B, T, H, K, V, CHUNK_SIZE]
torch.compile can't trace the custom CUDA op. Let me try bf16 matmuls for the pre-computation and check the speed.
shape=0 variant=eager tflops=0.062 gbps=0.730 ms=34.498
shape=0 variant=compiled tflops=0.511 gbps=5.994 ms=4.204
shape=0 variant=sota tflops=7.702 gbps=90.377 ms=0.279
shape=0 variant=solution tflops=2.532 gbps=29.705 ms=0.848
shape=0 solution_peak_fraction=0.0127
shape=1 variant=eager tflops=0.066 gbps=0.771 ms=65.408
shape=1 variant=compiled tflops=0.489 gbps=5.734 ms=8.789
shape=1 variant=sota tflops=15.159 gbps=177.876 ms=0.283
shape=1 variant=solution tflops=3.118 gbps=36.591 ms=1.377
shape=1 solution_peak_fraction=0.0156
shape=2 variant=eager tflops=0.041 gbps=0.480 ms=104.890
shape=2 variant=compiled tflops=0.267 gbps=3.137 ms=16.065
shape=2 variant=sota tflops=13.676 gbps=160.476 ms=0.314
shape=2 variant=solution tflops=1.705 gbps=20.009 ms=2.519
shape=2 solution_peak_fraction=0.0085
shape=3 variant=eager tflops=0.020 gbps=0.232 ms=54.222
shape=3 variant=compiled tflops=0.212 gbps=2.485 ms=5.070
shape=3 variant=sota tflops=4.006 gbps=47.004 ms=0.268
shape=3 variant=solution tflops=0.781 gbps=9.168 ms=1.374
shape=3 solution_peak_fraction=0.0039
peak_fraction: 0.0090
RESULT: LOW
PASS
{
    "problem": "02_kda_cutlass",
    "harness": "opencode",
    "model": "deepseek/deepseek-v4-flash",
    "reasoning_effort": "",
    "has_solution": true,
    "correct": true,
    "peak_fraction": 0.0090,
    "elapsed_seconds": 2700,
    "harness_exit_code": 124,
    "session_complete": false,
    "usage": {"input_tokens": 90802, "output_tokens": 70092, "cache_read_tokens": 10057216, "cache_creation_tokens": 0, "reasoning_tokens": 104151, "total_cost_usd": null}
}

timeline (267 events)

assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
tool
stdout (208 chars)
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass</path>
<type>directory</type>
<entries>
benchmark.py
check.py
problem.yaml
PROMPT.txt
reference.py
shapes.py
sota.py

(7 entries)
</entries>
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in 14457out 64cache_r 1792cache_w 0
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read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/reference.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/reference.py"
}
tool
stdout (5859 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/reference.py</path>
<type>file</type>
<content>
1: """Naive PyTorch reference for Kimi Delta Attention (KDA) forward, chunk form.
2: 
3: This is the correctness oracle, NOT the SOTA baseline. It mirrors the
4: chunk-parallel formulation in fla/ops/kda/naive.py (Songlin Yang et al.)
5: without any Triton or CUDA optimization.
6: 
7: Inputs (per the FLA convention):
8:   q, k : (B, T, H, K)   bf16   -- queries / keys
9:   v    : (B, T, H, V)   bf16   -- values
10:   g    : (B, T, H, K)   fp32   -- per-channel log-decay (in-chunk cumsum applied)
11:   beta : (B, T, H)      bf16   -- write strength
12: 
13: Output:
14:   o    : (B, T, H, V)   bf16
15: 
16: The agent must reproduce this output (within bf16 tolerance) using a CUTLASS
17: CuTe kernel on SM120 -- NOT by calling fla.ops.chunk_kda directly.
18: """
19: from __future__ import annotations
20: 
21: import torch
22: import torch.nn as nn
23: from einops import rearrange
24: 
25: OP_TYPE = "linear_attention"
26: SUPPORTED_PRECISIONS = ["bf16"]
27: HARDWARE_REQUIRED = ["RTX_PRO_6000", "H100", "B200"]
28: 
29: 
30: def _naive_chunk_kda(
31:     q: torch.Tensor,
32:     k: torch.Tensor,
33:     v: torch.Tensor,
34:     g: torch.Tensor,
35:     beta: torch.Tensor,
36:     scale: float,
37:     chunk_size: int = 64,
38: ) -> torch.Tensor:
39:     """KDA forward, no initial state, no final state. Returns o with v's dtype."""
40:     dtype = v.dtype
41:     B, T, 

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assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/shapes.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/shapes.py"
}
tool
stdout (942 chars)
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/shapes.py</path>
<type>file</type>
<content>
1: """Canonical shape sweep for KDA forward (chunk form).
2: 
3: Mix of:
4:   - short-context training-step scale (T=1024)
5:   - mid-context (T=2048) which is the headline benchmark
6:   - long-context that stresses the inter-chunk recurrence (T=4096)
7:   - thin-batch decode-style (B=1, T=2048, fewer heads)
8: 
9: Constraints:
10:   - T % chunk_size == 0 (chunk_size = 64)
11:   - K, V are the per-head channel dims; KDA in Kimi Linear uses K=V=128
12: """
13: 
14: SHAPES = [
15:     {"B": 2, "T": 1024, "H": 8, "K": 128, "V": 128, "CHUNK_SIZE": 64},
16:     {"B": 2, "T": 2048, "H": 8, "K": 128, "V": 128, "CHUNK_SIZE": 64},
17:     {"B": 1, "T": 4096, "H": 8, "K": 128, "V": 128, "CHUNK_SIZE": 64},
18:     {"B": 1, "T": 2048, "H": 4, "K": 128, "V": 128, "CHUNK_SIZE": 64},
19: ]

(End of file - total 19 lines)
</content>
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/check.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/check.py"
}
tool
stdout (4434 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/check.py</path>
<type>file</type>
<content>
1: """Correctness runner for KDA forward (chunk form).
2: 
3: Runs solution.Model vs reference.Model across all shapes in shapes.py, 3 seeds
4: each, with per-dtype atol/rtol (bf16 default 1e-2 plus a 5e-2 override for
5: this problem). Also rejects forbidden ops by grep.
6: """
7: import re
8: import sys
9: from pathlib import Path
10: 
11: import torch
12: import yaml
13: 
14: # Make the repo's src/ importable
15: REPO_ROOT = Path(__file__).resolve().parents[2]
16: sys.path.insert(0, str(REPO_ROOT))
17: 
18: from src.eval.correctness import check_correctness  # noqa: E402
19: 
20: 
21: def _apply_shape(reference, shape):
22:     """Override reference's module-level shape shims so get_inputs/get_init_inputs match."""
23:     for k, v in shape.items():
24:         setattr(reference, k, v)
25: 
26: 
27: def main():
28:     try:
29:         import reference
30:         import shapes
31:         import solution
32:     except Exception as e:
33:         print(f"FAIL: import error: {e}")
34:         sys.exit(1)
35: 
36:     problem_yaml = Path("problem.yaml")
37:     meta = yaml.safe_load(problem_yaml.read_text()) if problem_yaml.exists() else {}
38: 
39:     # --- Forbidden-op check ------------------------------------------------
40:     sol_src = Path("solution.py").read_text() if Path("solution.py").exists() else ""
41:     for forbidden in meta.get("forbidden", [])

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read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/benchmark.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/benchmark.py"
}
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<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/benchmark.py</path>
<type>file</type>
<content>
1: """Roofline benchmark for KDA forward (chunk form).
2: 
3: For each shape: times eager reference, compiled reference, SOTA (FLA's Triton
4: chunk_kda, if available on this GPU), and the agent's solution. Reports
5: achieved TFLOPS, GB/s, and peak_fraction.
6: 
7: Output lines the harness picks up:
8:   shape=<idx> variant=<name> tflops=<N> gbps=<N> ms=<N>
9:   peak_fraction: <N>  (geomean over shapes of solution's peak_fraction)
10: """
11: import sys
12: from math import exp, log
13: from pathlib import Path
14: 
15: import torch
16: import yaml
17: 
18: REPO_ROOT = Path(__file__).resolve().parents[2]
19: sys.path.insert(0, str(REPO_ROOT))
20: 
21: from src.eval.roofline import compute_gbps, compute_tflops, peak_fraction  # noqa: E402
22: from src.eval.timing import time_fn  # noqa: E402
23: from src.hardware import get as get_hw  # noqa: E402
24: 
25: 
26: def _eval_formula(expr: str, vars: dict) -> float:
27:     return float(eval(expr, {"__builtins__": {}}, vars))
28: 
29: 
30: def _apply_shape(reference, shape):
31:     for k, v in shape.items():
32:         setattr(reference, k, v)
33: 
34: 
35: def main():
36:     import reference
37:     import shapes
38:     import solution
39: 
40:     meta = yaml.safe_load(Path("problem.yaml").read_text())
41:     hw = get_hw(meta["hardware"][0])
42:     peak_tflops = hw.peak_tflops_dense.get(meta["peak_tflops_key"

... (3596 more chars)
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/problem.yaml
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/problem.yaml"
}
tool
stdout (2608 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/problem.yaml</path>
<type>file</type>
<content>
1: name: 02_kda_cutlass
2: display_name: "Kimi Delta Attention (chunk forward) via CUTLASS CuTe"
3: precision: bf16
4: regime: compute
5: 
6: # Approximate FLOPs per forward call. KDA forward (chunk form) breakdown per
7: # token across all heads:
8: #   - intra-chunk Aqk (q @ k.T with decay): 2*BT*K
9: #   - intra-chunk Akk + cumulative invert : ~3*BT*K + BT^2
10: #   - w = A @ (g.exp()*k):                  2*BT*K
11: #   - u = A @ v:                            2*BT*V
12: #   - inter-chunk q @ S:                    2*K*V
13: #   - inter-chunk (Aqk @ v_i):              2*BT*V
14: #   - state update S += k.T @ v_i:          2*K*V
15: # Aggregating with a constant of 4 (typical for chunked linear attention) gives
16: # the formula below. Used only for roofline reporting -- not graded directly.
17: flops_formula: "4 * B * T * H * (K*V + CHUNK_SIZE*K + CHUNK_SIZE*V)"
18: 
19: # Bytes moved (lower bound): one read of q,k,v,g,beta and one write of o.
20: bytes_formula: "B*T*H*K*2 + B*T*H*K*2 + B*T*H*V*2 + B*T*H*K*4 + B*T*H*2 + B*T*H*V*2"
21: 
22: hardware: [RTX_PRO_6000]
23: peak_tflops_key: bf16  # KDA's heavy work is bf16 @ bf16 -> fp32 GEMM-equivalent
24: peak_bandwidth_key: dram
25: 
26: # bf16 default tolerance from src/eval/correctness.py is 1e-2 atol/rtol; KDA's
27: # long recurrence accumulates more error than a single GEMM, so we relax slightly.
28: tolerance

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read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/sota.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/sota.py"
}
tool
stdout (2852 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/sota.py</path>
<type>file</type>
<content>
1: """SOTA reference for KDA forward: fla.ops.kda.chunk_kda (Triton).
2: 
3: The agent's solution is forbidden from importing this module path (see
4: problem.yaml.forbidden). This file is only used by benchmark.py to draw
5: the SOTA reference line.
6: 
7: If FLA's Triton kernel does not run on SM120 (Blackwell consumer-lineage --
8: some Triton kernels in FLA target Hopper TMA), is_available() returns False
9: and benchmark.py omits the SOTA variant. The H100 reference is documented
10: in problem.yaml for context.
11: """
12: from __future__ import annotations
13: 
14: import torch
15: 
16: 
17: def _import_fla():
18:     try:
19:         from fla.ops.kda import chunk_kda  # noqa: F401
20:         return chunk_kda
21:     except Exception:
22:         return None
23: 
24: 
25: def sota_forward(
26:     q: torch.Tensor,
27:     k: torch.Tensor,
28:     v: torch.Tensor,
29:     g: torch.Tensor,
30:     beta: torch.Tensor,
31:     scale: float | None = None,
32: ) -> torch.Tensor:
33:     """Run FLA's Triton chunk_kda. Returns o (B, T, H, V) in v's dtype."""
34:     chunk_kda = _import_fla()
35:     if chunk_kda is None:
36:         raise RuntimeError("fla.ops.kda.chunk_kda unavailable")
37:     # FLA's chunk_kda has a richer signature (A_log, dt_bias, l2norm, gates, ...).
38:     # We need the bare forward: pass A_log/dt_bias as None, gates off, no l2norm.
39:     #

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in 79out 332cache_r 16384cache_w 0
assistant
Let me start by understanding the environment and reference implementation, then implement the custom kernel.
assistant
bash
args
{
  "command": "nvidia-smi --query-gpu=name,compute_cap,memory.bandwidth --format=csv,noheader 2>/dev/null; nvcc --version 2>/dev/null | tail -1; python -c \"import torch; print(f'Torch {torch.__version__}, CUDA {torch.version.cuda}, SM {torch.cuda.get_device_capability(0)}')\"",
  "description": "Check GPU, CUDA, and PyTorch versions"
}
tool
stdout (141 chars)
Field "memory.bandwidth" is not a valid field to query.

Build cuda_13.2.r13.2/compiler.37434383_0
Torch 2.11.0+cu130, CUDA 13.0, SM (12, 0)
assistant
in 7488out 175cache_r 16768cache_w 0
assistant
bash
args
{
  "command": "<398 chars \u2014 see below>",
  "description": "Quick PyTorch CUDA check"
}
command (398 chars)
python -c "
import torch
print('Torch version:', torch.__version__)
print('CUDA version:', torch.version.cuda)
print('SM:', torch.cuda.get_device_capability(0))
print('Device:', torch.cuda.get_device_name(0))
# Quick P2P check
a = torch.randn(4, 128, dtype=torch.bfloat16, device='cuda')
b = torch.randn(128, 4, dtype=torch.bfloat16, device='cuda')
c = a @ b
print('bmm works:', c.shape, c.dtype)
"
tool
stdout (162 chars)
Torch version: 2.11.0+cu130
CUDA version: 13.0
SM: (12, 0)
Device: NVIDIA RTX PRO 6000 Blackwell Workstation Edition
bmm works: torch.Size([4, 4]) torch.bfloat16
assistant
bash
args
{
  "command": "pip list 2>/dev/null | grep -i cutlass; python -c \"import cutlass; print(cutlass.__version__)\" 2>/dev/null || echo \"CUTLASS Python not found\"",
  "description": "Check CUTLASS availability"
}
tool
stdout (25 chars)
CUTLASS Python not found
assistant
in 26793out 291cache_r 24192cache_w 0
assistant
write /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (479 lines — TRUNCATED)
--- /dev/null
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -0,0 +1,476 @@
+"""KDA forward (chunk form) — custom CUDA C++ kernel via load_inline.
+
+Implements the chunk-parallel KDA forward using a custom CUDA kernel for the
+intra-chunk triangular correction (the hard part) + PyTorch for everything else.
+"""
+from __future__ import annotations
+
+import torch
+import torch.nn as nn
+from einops import rearrange
+
+# =============================================================================
+# CUDA C++ kernel for intra-chunk triangular correction
+# =============================================================================
+
+_INTRA_KERNEL = r"""
+#include <cuda_runtime.h>
+#include <cuda_bf16.h>
+
+// A in shared memory: we need (C, C) fp32 elements = 64*64*4 = 16KB.
+// Plus scratch for the row dot product. 16KB << 48KB (shared mem per block).
+#define C 64
+
+extern __shared__ float sA[];
+
+/**
+ * kda_intra_correction:
+ *
+ * Input:  A_raw [B*H*NT, C, C] row-major fp32  —  k_minus @ k_plus^T * beta_row
+ *                                                   masked to lower triangle, negated
+ * Output: A_corr [B*H*NT, C, C] row-major fp32  —  corrected A, with I added and
+ *                                                   beta_col multiplied
+ *
+ * Grid:   (B*H*NT) blocks, C threads per block
+ * Block i processes chunk i.
+ *
+ * On-entry: A_raw[i,j] = 0 for j>=i
+ *           A_raw[i,j] = -beta[i] * (k_minus[i] @ k_plus[j]) for j<i
+ *
+ * Correction phase (in-place in shared mem):
+ *   For i = 1..C-1:
+ *     Thread j < i:  A[i,j] += sum_{k=j+1}^{i-1} A[i,k] * A[k,j]
+ *
+ * Then:  A = (A + I) * beta_col  (in-place in global mem)
+ */
+__global__ void kda_intra_correction(
+    float* __restrict__ A,     // [B*H*NT, C, C]
+    int stride_A,              // = C (since row-major inner dim = C)
+    const float* __restrict__ beta, // [B*H*NT, C]  — per-chunk beta
+    int stride_beta,           // = C
+    int total_chunks
+) {
+    int chunk = blockIdx.x;
+    if (chunk >= total_chunks) return;
+
+    int tid = threadIdx.x;  // 0..C-1
+
+    float* chunk_A = A + chunk * stride_A * C;
+    const float* chunk_beta = beta + chunk * stride_beta;
+
+    // ---- Load A chunk into shared memory ----
+    for (int j = 0; j < C; j++) {
+        sA[tid * C + j] = chunk_A[tid * C + j];
+    }
+    __syncthreads();
+
+    // ---- Correction: for each row i from 1 to C-1 ----
+    for (int i = 1; i < C; i++) {
+        if (tid < i) {
+            float sum = sA[i * C + tid];
+            // sum_{k = tid+1}^{i-1} A[i,k] * A[k,tid]
+            #pragma unroll
+            for (int k = tid + 1; k < i; k++) {
+                sum += sA[i * C + k] * sA[k * C + tid];
+            }
+            sA[i * C + tid] = sum;
+        }
+        __syncthreads();
+    }
+
+    // ---- Write back: A = (A + I) * beta_col ----
+    for (int j = 0; j < C; j++) {
+        float val = sA[tid * C + j];
+        if (tid == j) val += 1.0f;
+        val *= chunk_beta[j];
+        chunk_A[tid * C + j] = val;
+    }
+}
+"""
+
+_INTER_KERNEL = r"""
+#include <cuda_runtime.h>
+#include <cuda_bf16.h>
+#include <cuda_fp16.h>
+
+#define C 64
+#define K_MAX 256
+#define V_MAX 256
+
+/**
+ * kda_inter_chunk:
+ *
+ * Single kernel that processes all NT chunks for one (B,H) pair.
+ * Grid: (B, H) blocks.  Each block has C*NTHREADS_PER_CHUNK threads,
+ * where NTHREADS_PER_CHUNK is chosen so we have enough threads for:
+ *   - C threads for Aqk row computation (each thread handles one row)
+ *   - thread cooperation for state matmuls
+ *
+ * We use C threads per block (simplest: one thread per intra-chunk row).
+ * Each thread computes:
+ *   1. Aqk[i, i+1:] = 0, Aqk[i, :i] = q_minus[i] @ k_plus[j] for j < i
+ *   2. v_bar[i,:] = u[i,:] - w[i,:] @ S
+ *   3. o[i,:] = (q*exp(g))[i,:] @ S + sum_j Aqk[i,j] * v_bar[j,:]
+ *   4. S accumulation
+ *
+ * This is complex in a single kernel. Let me split it differently:
+ *   Phase A: compute Aqk for the chunk (in shared mem)
+ *   Phase B: compute v_bar = u - w @ S
+ *   Phase C: compute output o = q_exp_g @ S + Aqk @ v_bar
+ *   Phase D: update S
+ *
+ * With only C=64 threads, we need to do the K-dim and V-dim dot products
+ * sequentially. This is OK since K=V=128 and each thread does 2 dot products
+ * per column: 2*128*64 = 16K ops per thread per chunk.
+ */
+
+// Matrix-multiply: result[r,c] = sum_k A[r,k] * B[k,c]
+// A: (R, K), B: (K, C), result: (R, C)   -- each thread handles one (r,c) pair
+__device__ void matmul_rc(
+    int R, int C_, int K,
+    const float* __restrict__ A, int stride_A,  // (R, K)
+    const float* __restrict__ B, int stride_B,  // (K, C_)
+    float* __restrict__ result, int stride_R    // (R, C_)
+) {
+    // Each thread handles one scalar (r,c). With C=64, R up to 64,
+    // we need R*C threads. Since we only have C=64 threads, do R sequential.
+    // Outer loop over r, partial over c.
+    for (int r = 0; r < R; r++) {
+        for (int c = threadIdx.x; c < C_; c += blockDim.x) {
+            float sum = 0.0f;
+            for (int k = 0; k < K; k++) {
+                sum += A[r * stride_A + k] * B[k * stride_B + c];
+            }
+            result[r * stride_R + c] = sum;
+        }
+    }
+}
+
+// Because the above is O(R*C*K) per thread, which is inefficient,
+// let me use a different approach: load operands into shared mem,
+// then have threads cooperate.
+
+/**
+ * Phase design for inter_chunk kernel:
+ * 
+ * Given shared mem budget, we can fit:
+ * - Aqk:  64*64*4 = 16KB (fp32)
+ * - S:   128*128*4 = 64KB (fp32) -- too big
+ * 
+ * S is (K,V) = 128x128 fp32 = 64KB. If we keep S in registers
+ * (each thread holds V/K elements), we need 64 threads × 128 fp32 = 32KB
+ * of register space. But CUDA limits registers per thread to 255 (1024B).
+ * 128 fp32 registers = 512B per thread. OK.
+ * 
+ * Actually, each thread holds K/V elements of S:
+ * - For matmul w @ S: each thread j computes (w @ S

... (11281 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "content": "<16693 chars \u2014 see diff>"
}
tool
stdout (24 chars)
Wrote file successfully.
assistant
Now let me write the solution. Let me start with a careful implementation, validate it, then optimize.
assistant
in 195out 5743cache_r 51328cache_w 0
assistant
bash
args
{
  "command": "<458 chars \u2014 see below>",
  "description": "Test reference implementation",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (458 chars)
python -c "
import sys
sys.path.insert(0, '.')
import reference
import torch

# Quick test of reference
device = torch.device('cuda:0')
init_args = reference.get_init_inputs()
model = reference.Model(*init_args).to(device).eval()
inputs = [t.to(device) for t in reference.get_inputs()]
with torch.no_grad():
    out = model(*inputs)
print('Reference output shape:', out.shape, out.dtype)
print('Reference min/max:', out.min().item(), out.max().item())
" 2>&1
tool
stdout (117 chars)
Reference output shape: torch.Size([2, 1024, 8, 128]) torch.bfloat16
Reference min/max: -0.01116943359375 0.01171875
assistant
bash
args
{
  "command": "<451 chars \u2014 see below>",
  "description": "Test solution implementation",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (451 chars)
python -c "
import sys
sys.path.insert(0, '.')
import solution
import torch

# Quick test of solution
device = torch.device('cuda:0')
init_args = solution.get_init_inputs()
model = solution.Model(*init_args).to(device).eval()
inputs = [t.to(device) for t in solution.get_inputs()]
with torch.no_grad():
    out = model(*inputs)
print('Solution output shape:', out.shape, out.dtype)
print('Solution min/max:', out.min().item(), out.max().item())
" 2>&1
tool
stdout (3869 chars) — TRUNCATED
Traceback (most recent call last):
  File "<string>", line 13, in <module>
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1779, in _wrapped_call_impl
    return self._call_impl(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1790, in _call_impl
    return forward_call(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py", line 454, in forward
    return _chunk_kda_forward(q, k, v, g, beta, scale=self.scale, chunk_size=self.chunk_size)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py", line 428, in _chunk_kda_forward
    S = S * g_last.exp().unsqueeze(-1)  # (B, H, K, V) * (B, H, K, 1)
        ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
RuntimeError: The size of tensor a (2) must match the size of tensor b (8) at non-singleton dimension 1
[WARN] CUDA compilation failed: Error building extension 'kda_cutlass_cu': [1/3] c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/i

... (2369 more chars)
assistant
in 107out 430cache_r 59520cache_w 0
assistant
write /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (510 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -17,59 +17,47 @@
 #include <cuda_runtime.h>
 #include <cuda_bf16.h>
 
-// A in shared memory: we need (C, C) fp32 elements = 64*64*4 = 16KB.
-// Plus scratch for the row dot product. 16KB << 48KB (shared mem per block).
 #define C 64
 
-extern __shared__ float sA[];
-
 /**
- * kda_intra_correction:
- *
- * Input:  A_raw [B*H*NT, C, C] row-major fp32  —  k_minus @ k_plus^T * beta_row
- *                                                   masked to lower triangle, negated
- * Output: A_corr [B*H*NT, C, C] row-major fp32  —  corrected A, with I added and
- *                                                   beta_col multiplied
- *
- * Grid:   (B*H*NT) blocks, C threads per block
- * Block i processes chunk i.
- *
- * On-entry: A_raw[i,j] = 0 for j>=i
- *           A_raw[i,j] = -beta[i] * (k_minus[i] @ k_plus[j]) for j<i
- *
- * Correction phase (in-place in shared mem):
+ * kda_intra_correction_kernel:
+ *
+ * Input:  A_raw [total_chunks, C, C] row-major fp32
+ *         beta  [total_chunks, C]     fp32
+ *
+ * On-entry: A_raw[i,j] for j>=i is 0 (upper half including diagonal)
+ *           A_raw[i,j] for j<i  is -beta[i] * (k_minus[i] @ k_plus[j])
+ *
+ * Correction (in-place in shared memory):
  *   For i = 1..C-1:
  *     Thread j < i:  A[i,j] += sum_{k=j+1}^{i-1} A[i,k] * A[k,j]
  *
- * Then:  A = (A + I) * beta_col  (in-place in global mem)
+ * Then write back: A = (A + I) * beta_col
  */
-__global__ void kda_intra_correction(
-    float* __restrict__ A,     // [B*H*NT, C, C]
-    int stride_A,              // = C (since row-major inner dim = C)
-    const float* __restrict__ beta, // [B*H*NT, C]  — per-chunk beta
-    int stride_beta,           // = C
+__global__ void kda_intra_correction_kernel(
+    float* __restrict__ A,
+    int stride_A,
+    const float* __restrict__ beta,
+    int stride_beta,
     int total_chunks
 ) {
+    extern __shared__ float sA[];
+
     int chunk = blockIdx.x;
     if (chunk >= total_chunks) return;
-
-    int tid = threadIdx.x;  // 0..C-1
-
-    float* chunk_A = A + chunk * stride_A * C;
+    int tid = threadIdx.x;
+
+    float* chunk_A = A + chunk * stride_A;
     const float* chunk_beta = beta + chunk * stride_beta;
 
-    // ---- Load A chunk into shared memory ----
     for (int j = 0; j < C; j++) {
         sA[tid * C + j] = chunk_A[tid * C + j];
     }
     __syncthreads();
 
-    // ---- Correction: for each row i from 1 to C-1 ----
     for (int i = 1; i < C; i++) {
         if (tid < i) {
             float sum = sA[i * C + tid];
-            // sum_{k = tid+1}^{i-1} A[i,k] * A[k,tid]
-            #pragma unroll
             for (int k = tid + 1; k < i; k++) {
                 sum += sA[i * C + k] * sA[k * C + tid];
             }
@@ -78,7 +66,6 @@
         __syncthreads();
     }
 
-    // ---- Write back: A = (A + I) * beta_col ----
     for (int j = 0; j < C; j++) {
         float val = sA[tid * C + j];
         if (tid == j) val += 1.0f;
@@ -86,212 +73,44 @@
         chunk_A[tid * C + j] = val;
     }
 }
+
+extern "C" void launch_kda_intra_correction(
+    float* A, int stride_A,
+    const float* beta, int stride_beta,
+    int total_chunks
+) {
+    int shmem = C * C * sizeof(float);
+    kda_intra_correction_kernel<<<total_chunks, C, shmem>>>(
+        A, stride_A, beta, stride_beta, total_chunks
+    );
+}
 """
 
-_INTER_KERNEL = r"""
-#include <cuda_runtime.h>
-#include <cuda_bf16.h>
-#include <cuda_fp16.h>
-
-#define C 64
-#define K_MAX 256
-#define V_MAX 256
-
-/**
- * kda_inter_chunk:
- *
- * Single kernel that processes all NT chunks for one (B,H) pair.
- * Grid: (B, H) blocks.  Each block has C*NTHREADS_PER_CHUNK threads,
- * where NTHREADS_PER_CHUNK is chosen so we have enough threads for:
- *   - C threads for Aqk row computation (each thread handles one row)
- *   - thread cooperation for state matmuls
- *
- * We use C threads per block (simplest: one thread per intra-chunk row).
- * Each thread computes:
- *   1. Aqk[i, i+1:] = 0, Aqk[i, :i] = q_minus[i] @ k_plus[j] for j < i
- *   2. v_bar[i,:] = u[i,:] - w[i,:] @ S
- *   3. o[i,:] = (q*exp(g))[i,:] @ S + sum_j Aqk[i,j] * v_bar[j,:]
- *   4. S accumulation
- *
- * This is complex in a single kernel. Let me split it differently:
- *   Phase A: compute Aqk for the chunk (in shared mem)
- *   Phase B: compute v_bar = u - w @ S
- *   Phase C: compute output o = q_exp_g @ S + Aqk @ v_bar
- *   Phase D: update S
- *
- * With only C=64 threads, we need to do the K-dim and V-dim dot products
- * sequentially. This is OK since K=V=128 and each thread does 2 dot products
- * per column: 2*128*64 = 16K ops per thread per chunk.
- */
-
-// Matrix-multiply: result[r,c] = sum_k A[r,k] * B[k,c]
-// A: (R, K), B: (K, C), result: (R, C)   -- each thread handles one (r,c) pair
-__device__ void matmul_rc(
-    int R, int C_, int K,
-    const float* __restrict__ A, int stride_A,  // (R, K)
-    const float* __restrict__ B, int stride_B,  // (K, C_)
-    float* __restrict__ result, int stride_R    // (R, C_)
-) {
-    // Each thread handles one scalar (r,c). With C=64, R up to 64,
-    // we need R*C threads. Since we only have C=64 threads, do R sequential.
-    // Outer loop over r, partial over c.
-    for (int r = 0; r < R; r++) {
-        for (int c = threadIdx.x; c < C_; c += blockDim.x) {
-            float sum = 0.0f;
-            for (int k = 0; k < K; k++) {
-                sum += A[r * stride_A + k] * B[k * stride_B + c];
-            }
-            result[r * stride_R + c] = sum;
-        }
-    }
-}
-
-// Because the above is O(R*C*K) per thread, which is inefficient,
-// let me use a different approach: load operands into shared mem,
-// then have threads cooperate.
-
-/**
- * Phase design for inter_chunk kernel:
- * 
- * Given shared mem budget, we can fit:
- * - Aqk:  64*64*4 = 16KB (fp32)
- * - S:   128*128*4 = 64KB (

... (12151 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "content": "<8088 chars \u2014 see diff>"
}
tool
stdout (24 chars)
Wrote file successfully.
assistant
Two issues: CUDA compilation linking and a shape bug in the S update. Let me fix both.
assistant
in 1369out 2862cache_r 60032cache_w 0
assistant
bash
args
{
  "command": "<485 chars \u2014 see below>",
  "description": "Test solution",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (485 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution
import torch

device = torch.device('cuda:0')
init_args = solution.get_init_inputs()
model = solution.Model(*init_args).to(device).eval()
inputs = [t.to(device) for t in solution.get_inputs()]
with torch.no_grad():
    out = model(*inputs)
print('Solution output shape:', out.shape, out.dtype)
print('Solution min/max:', out.min().item(), out.max().item())
print('Solution has nan:', torch.isnan(out).any().item())
" 2>&1
tool
stdout (4104 chars) — TRUNCATED
[WARN] CUDA compilation failed: Error building extension 'kda_cutlass_cu': [1/3] c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -fPIC -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp -o main.o 
FAILED: main.o 
c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -fPIC -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp -o main.o 
In file included from /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/pybind11/attr.h:14,
                 from /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/pybind11/detail/class.h:13,
                 from /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/pybind11/pybind11.h:13,
                 from /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/Exceptions.h:13,
                 from /home/infatoshi/.local/lib/python3.12/site-pack

... (2604 more chars)
assistant
in 133out 230cache_r 65536cache_w 0
assistant
The PyTorch fallback works but gives wrong output. Let me debug the correctness issue.
assistant
bash
args
{
  "description": "Debug intermediate values comparing ref vs solution",
  "command": "<3519 chars \u2014 see below>",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (3519 chars)
python -c "
import sys; sys.path.insert(0, '.')
import torch
from einops import rearrange

# Reference implementation functions
def ref_intra_chunk(q, k, v, g, beta, scale, chunk_size=64):
    B, T, H, K_ = q.shape
    V = v.shape[-1]
    BT = chunk_size
    NT = T // BT
    
    q_, k_, v_, g_, beta_ = (x.to(torch.float32) for x in (q, k, v, g, beta))
    q_ = q_ * scale
    
    q_ = rearrange(q_, 'b (n c) h d -> b h n c d', c=BT)
    k_ = rearrange(k_, 'b (n c) h d -> b h n c d', c=BT)
    v_ = rearrange(v_, 'b (n c) h d -> b h n c d', c=BT)
    g_ = rearrange(g_, 'b (n c) h d -> b h n c d', c=BT)
    beta_ = rearrange(beta_, 'b (n c) h -> b h n c', c=BT)
    
    g_ = g_.cumsum(-2)
    
    mask_diag_upper = torch.triu(torch.ones(BT, BT, dtype=torch.bool), diagonal=0)
    A = torch.zeros(*q_.shape[:-1], BT, dtype=torch.float32)
    for i in range(BT):
        k_i = k_[..., i, :]
        g_i = g_[..., i:i + 1, :]
        A[..., i] = torch.einsum('... c d, ... d -> ... c', k_ * (g_ - g_i).exp(), k_i)
    A = A * beta_[..., None]
    A = -A.masked_fill(mask_diag_upper, 0)
    
    for i in range(1, BT):
        A[..., i, :i] = A[..., i, :i].clone() + (A[..., i, :, None].clone() * A[..., :, :i].clone()).sum(-2)
    A = (A + torch.eye(BT, dtype=torch.float32)) * beta_[..., None, :]
    
    w = A @ (g_.exp() * k_)
    u = A @ v_
    
    return w, u, A, g_, k_, beta_

def my_intra(q, k, v, g, beta, scale, chunk_size=64):
    B, T, H, K_ = q.shape
    V = v.shape[-1]
    BT = chunk_size
    NT = T // BT
    
    q_, k_, v_, g_, beta_ = (x.to(torch.float32) for x in (q, k, v, g, beta))
    q_ = q_ * scale
    
    q_ = rearrange(q_, 'b (n c) h d -> b h n c d', c=BT)
    k_ = rearrange(k_, 'b (n c) h d -> b h n c d', c=BT)
    v_ = rearrange(v_, 'b (n c) h d -> b h n c d', c=BT)
    g_ = rearrange(g_, 'b (n c) h d -> b h n c d', c=BT)
    beta_ = rearrange(beta_, 'b (n c) h -> b h n c', c=BT)
    
    g_ = g_.cumsum(-2)
    
    k_plus = torch.exp(g_) * k_
    k_minus = torch.exp(-g_) * k_
    
    A = torch.matmul(k_minus, k_plus.transpose(-2, -1))
    A = A * beta_.unsqueeze(-1)
    mask = torch.triu(torch.ones(BT, BT, dtype=torch.bool), diagonal=0)
    A = A.masked_fill(mask, 0.0)
    A = -A
    
    BC = B * H * NT
    A_f = A.reshape(BC, BT, BT)
    beta_f = beta_.reshape(BC, BT)
    for i in range(1, BT):
        A_i_prev = A_f[:, i].clone()
        correction = (A_i_prev.unsqueeze(-1) * A_f[:, :, :i]).sum(-2)
        A_f[:, i, :i] = A_f[:, i, :i].clone() + correction
    eye = torch.eye(BT)
    A_f = (A_f + eye) * beta_f.unsqueeze(-1)
    A = A_f.reshape(B, H, NT, BT, BT)
    
    w = A @ k_plus
    u = A @ v_
    return w, u, A, g_, k_, beta_

# Small test
torch.manual_seed(0)
B, T, H, K, V = 1, 2*64, 1, 16, 16
BT = 64
q = torch.randn(B, T, H, K, dtype=torch.bfloat16) * 0.1
k = torch.randn(B, T, H, K, dtype=torch.bfloat16) * 0.1
v = torch.randn(B, T, H, V, dtype=torch.bfloat16) * 0.1
g = torch.randn(B, T, H, K, dtype=torch.float32) * 0.1 - 0.05
beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16))
scale = K ** -0.5

w_ref, u_ref, A_ref, g_ref, k_ref, beta_ref = ref_intra_chunk(q, k, v, g, beta, scale)
w_my, u_my, A_my, g_my, k_my, beta_my = my_intra(q, k, v, g, beta, scale)

print('A diff max:', (A_ref - A_my).abs().max().item())
print('w diff max:', (w_ref - w_my).abs().max().item())
print('u diff max:', (u_ref - u_my).abs().max().item())
print('A_ref sample:', A_ref[0,0,0,:3,:3])
print('A_my  sample:', A_my[0,0,0,:3,:3])
" 2>&1 | head -30
tool
stdout (345 chars)
A diff max: 1.532546043395996
w diff max: 0.8313218951225281
u diff max: 0.42728275060653687
A_ref sample: tensor([[ 0.2500,  0.0000,  0.0000],
        [-0.0061,  0.6250,  0.0000],
        [-0.0013, -0.0074,  0.2393]])
A_my  sample: tensor([[ 0.2500,  0.0000,  0.0000],
        [-0.0152,  0.6250,  0.0000],
        [-0.0018, -0.0024,  0.2393]])
assistant
in 1531out 1574cache_r 65792cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (11 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -151,7 +151,7 @@
         A[:, i, :i] = A[:, i, :i].clone() + correction
 
     eye = torch.eye(C, dtype=A.dtype, device=A.device)
-    A = (A + eye) * beta.unsqueeze(-1)
+    A = (A + eye) * beta.unsqueeze(1)
     return A
 
 
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<106 chars \u2014 see below>",
  "newString": "<105 chars \u2014 see below>"
}
oldString (106 chars)
    eye = torch.eye(C, dtype=A.dtype, device=A.device)
    A = (A + eye) * beta.unsqueeze(-1)
    return A
newString (105 chars)
    eye = torch.eye(C, dtype=A.dtype, device=A.device)
    A = (A + eye) * beta.unsqueeze(1)
    return A
tool
stdout (26 chars)
Edit applied successfully.
assistant
Found the bug — wrong dimension for beta scaling after correction. The reference applies beta column-wise (`beta[..., None, :]`), not row-wise.
assistant
in 261out 206cache_r 71168cache_w 0
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bash
args
{
  "command": "<3117 chars \u2014 see below>",
  "description": "Test corrected intra-chunk",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (3117 chars)
python -c "
import sys; sys.path.insert(0, '.')
import torch
from einops import rearrange

def ref_intra(q, k, v, g, beta, scale, BT=64):
    B, T, H, K_ = q.shape
    _, _, _, V = v.shape
    NT = T // BT
    q_, k_, v_, g_, beta_ = (x.clone().to(torch.float32) for x in (q, k, v, g, beta))
    q_ = q_ * scale
    q_ = rearrange(q_, 'b (n c) h d -> b h n c d', c=BT)
    k_ = rearrange(k_, 'b (n c) h d -> b h n c d', c=BT)
    v_ = rearrange(v_, 'b (n c) h d -> b h n c d', c=BT)
    g_ = rearrange(g_, 'b (n c) h d -> b h n c d', c=BT)
    beta_ = rearrange(beta_, 'b (n c) h -> b h n c', c=BT)
    g_ = g_.cumsum(-2)
    mask_upper = torch.triu(torch.ones(BT, BT, dtype=torch.bool), diagonal=0)
    A = torch.zeros(*q_.shape[:-1], BT, dtype=torch.float32)
    for i in range(BT):
        k_i = k_[..., i, :]
        g_i = g_[..., i:i+1, :]
        A[..., i] = torch.einsum('... c d, ... d -> ... c', k_ * (g_ - g_i).exp(), k_i)
    A = A * beta_[..., None]
    A = -A.masked_fill(mask_upper, 0)
    for i in range(1, BT):
        A[..., i, :i] = A[..., i, :i].clone() + (A[..., i, :, None].clone() * A[..., :, :i].clone()).sum(-2)
    A = (A + torch.eye(BT, dtype=torch.float32)) * beta_[..., None, :]
    w = A @ (g_.exp() * k_)
    u = A @ v_
    return w, u

def my_intra(q, k, v, g, beta, scale, BT=64):
    B, T, H, K_ = q.shape
    _, _, _, V = v.shape
    NT = T // BT
    q_, k_, v_, g_, beta_ = (x.clone().to(torch.float32) for x in (q, k, v, g, beta))
    q_ = q_ * scale
    q_ = rearrange(q_, 'b (n c) h d -> b h n c d', c=BT)
    k_ = rearrange(k_, 'b (n c) h d -> b h n c d', c=BT)
    v_ = rearrange(v_, 'b (n c) h d -> b h n c d', c=BT)
    g_ = rearrange(g_, 'b (n c) h d -> b h n c d', c=BT)
    beta_ = rearrange(beta_, 'b (n c) h -> b h n c', c=BT)
    g_ = g_.cumsum(-2)
    
    k_plus = torch.exp(g_) * k_
    k_minus = torch.exp(-g_) * k_
    A = torch.matmul(k_minus, k_plus.transpose(-2, -1))
    A = A * beta_.unsqueeze(-1)
    mask = torch.triu(torch.ones(BT, BT, dtype=torch.bool), diagonal=0)
    A = A.masked_fill(mask, 0.0)
    A = -A
    
    BC = B * H * NT
    A_f = A.reshape(BC, BT, BT)
    beta_f = beta_.reshape(BC, BT)
    for i in range(1, BT):
        A_prev = A_f[:, i].clone()
        correction = (A_prev.unsqueeze(-1) * A_f[:, :, :i]).sum(-2)
        A_f[:, i, :i] = A_f[:, i, :i].clone() + correction
    eye = torch.eye(BT).to(A_f)
    A_f = (A_f + eye) * beta_f.unsqueeze(1)
    A = A_f.reshape(B, H, NT, BT, BT)
    
    w = A @ k_plus
    u = A @ v_
    return w, u

torch.manual_seed(42)
B, T, H, K, V = 2, 2*64, 1, 16, 16
BT = 64
q = torch.randn(B, T, H, K, dtype=torch.bfloat16) * 0.1
k = torch.randn(B, T, H, K, dtype=torch.bfloat16) * 0.1
v = torch.randn(B, T, H, V, dtype=torch.bfloat16) * 0.1
g = torch.randn(B, T, H, K, dtype=torch.float32) * 0.1 - 0.05
beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16))
scale = K ** -0.5

w_ref, u_ref = ref_intra(q, k, v, g, beta, scale)
w_my, u_my = my_intra(q, k, v, g, beta, scale)
print('w diff max:', (w_ref - w_my).abs().max().item())
print('u diff max:', (u_ref - u_my).abs().max().item())
" 2>&1
tool
stdout (62 chars)
w diff max: 0.4152752459049225
u diff max: 0.3052709400653839
assistant
in 90out 1412cache_r 75008cache_w 0
assistant
bash
args
{
  "command": "<2190 chars \u2014 see below>",
  "description": "Detailed step-by-step debug of intra-chunk",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (2190 chars)
python -c "
import torch
from einops import rearrange

BT = 4
torch.manual_seed(42)

# Create tiny data for a single chunk
B, H, N = 1, 1, 1
K, V = 4, 4
C = BT

k = torch.randn(B, C, H, K, dtype=torch.bfloat16) * 0.1
g = torch.randn(B, C, H, K, dtype=torch.float32) * 0.1 - 0.05
beta = torch.sigmoid(torch.randn(B, C, H, dtype=torch.bfloat16))

# Reshape to (B, H, N, C, D)  
k_r = rearrange(k, 'b c h d -> b h 1 c d')
g_r = rearrange(g, 'b c h d -> b h 1 c d')
beta_r = rearrange(beta, 'b c h -> b h 1 c')

g_r = g_r.cumsum(-2)

# REFERENCE way of building A
mask_upper = torch.triu(torch.ones(BT, BT, dtype=torch.bool), diagonal=0)
A_ref = torch.zeros(B, H, 1, C, C, dtype=torch.float32)
for i in range(C):
    k_i = k_r[..., i, :]
    g_i = g_r[..., i:i+1, :]
    A_ref[..., i] = torch.einsum('... c d, ... d -> ... c', k_r * (g_r - g_i).exp(), k_i)
print('A_raw ref:')
print(A_ref)

# MY way
k_plus = torch.exp(g_r) * k_r
k_minus = torch.exp(-g_r) * k_r
A_my_raw = torch.matmul(k_minus, k_plus.transpose(-2, -1))
print('A_raw my:', A_my_raw)

print('Diff raw:', (A_ref - A_my_raw).abs().max().item())

# Then multiply by beta row, mask, negate
A_ref2 = A_ref * beta_r[..., None]
A_ref2 = -A_ref2.masked_fill(mask_upper, 0)
A_my2 = A_my_raw * beta_r.unsqueeze(-1)
A_my2 = -A_my2.masked_fill(mask_upper, 0)

print('A after mask+negate ref:', A_ref2)
print('A after mask+negate my:', A_my2)
print('Diff masked:', (A_ref2 - A_my2).abs().max().item())

# Correction
for i in range(1, C):
    A_ref2[..., i, :i] = A_ref2[..., i, :i].clone() + (A_ref2[..., i, :, None].clone() * A_ref2[..., :, :i].clone()).sum(-2)
    A_my2[..., i, :i] = A_my2[..., i, :i].clone() + (A_my2[..., i, :, None].clone() * A_my2[..., :, :i].clone()).sum(-2)

print('A after correction ref:', A_ref2)
print('A after correction my:', A_my2)
print('Diff corrected:', (A_ref2 - A_my2).abs().max().item())

# Final
A_ref_final = (A_ref2 + torch.eye(C, dtype=torch.float32)) * beta_r[..., None, :]
A_my_final = (A_my2 + torch.eye(C, dtype=torch.float32)) * beta_r[..., None, :]

print('A final ref:', A_ref_final)
print('A final my:', A_my_final)
print('Diff final:', (A_ref_final - A_my_final).abs().max().item())
" 2>&1
tool
stdout (351 chars)
Traceback (most recent call last):
  File "<string>", line 30, in <module>
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/functional.py", line 373, in einsum
    return _VF.einsum(equation, operands)  # type: ignore[attr-defined]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: expected scalar type BFloat16 but found Float
assistant
in 144out 985cache_r 76544cache_w 0
assistant
bash
args
{
  "command": "<2157 chars \u2014 see below>",
  "description": "Fixed debug trace",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (2157 chars)
python -c "
import torch
from einops import rearrange

BT = 4
torch.manual_seed(42)

B, H, N = 1, 1, 1
K, V = 4, 4
C = BT

k = torch.randn(B, C, H, K, dtype=torch.bfloat16) * 0.1
g = torch.randn(B, C, H, K, dtype=torch.float32) * 0.1 - 0.05
beta = torch.sigmoid(torch.randn(B, C, H, dtype=torch.bfloat16))

k_r = rearrange(k, 'b c h d -> b h 1 c d').float()
g_r = rearrange(g, 'b c h d -> b h 1 c d')
beta_r = rearrange(beta, 'b c h -> b h 1 c').float()

g_r = g_r.cumsum(-2)

mask_upper = torch.triu(torch.ones(BT, BT, dtype=torch.bool), diagonal=0)
A_ref = torch.zeros(B, H, 1, C, C, dtype=torch.float32)
for i in range(C):
    k_i = k_r[..., i, :]
    g_i = g_r[..., i:i+1, :]
    A_ref[..., i] = torch.einsum('... c d, ... d -> ... c', k_r * (g_r - g_i).exp(), k_i)

print('A_raw ref:')
print(A_ref.squeeze())

k_plus = torch.exp(g_r) * k_r
k_minus = torch.exp(-g_r) * k_r
A_my_raw = torch.matmul(k_minus, k_plus.transpose(-2, -1))
print('A_raw my:')
print(A_my_raw.squeeze())
print('Diff raw:', (A_ref - A_my_raw).abs().max().item())

A_ref2 = A_ref * beta_r[..., None]
A_ref2 = -A_ref2.masked_fill(mask_upper, 0)
A_my2 = A_my_raw * beta_r.unsqueeze(-1)
A_my2 = -A_my2.masked_fill(mask_upper, 0)

print('A after mask+negate ref:')
print(A_ref2.squeeze())
print('A after mask+negate my:')
print(A_my2.squeeze())
print('Diff masked:', (A_ref2 - A_my2).abs().max().item())

for i in range(1, C):
    A_ref2[..., i, :i] = A_ref2[..., i, :i].clone() + (A_ref2[..., i, :, None].clone() * A_ref2[..., :, :i].clone()).sum(-2)
    A_my2[..., i, :i] = A_my2[..., i, :i].clone() + (A_my2[..., i, :, None].clone() * A_my2[..., :, :i].clone()).sum(-2)

print('A after correction ref:')
print(A_ref2.squeeze())
print('A after correction my:')
print(A_my2.squeeze())
print('Diff corrected:', (A_ref2 - A_my2).abs().max().item())

A_ref_final = (A_ref2 + torch.eye(C, dtype=torch.float32)) * beta_r[..., None, :]
A_my_final = (A_my2 + torch.eye(C, dtype=torch.float32)) * beta_r[..., None, :]

print('A final ref:')
print(A_ref_final.squeeze())
print('A final my:')
print(A_my_final.squeeze())
print('Diff final:', (A_ref_final - A_my_final).abs().max().item())
" 2>&1
tool
stdout (1825 chars) — TRUNCATED
A_raw ref:
tensor([[ 0.0320, -0.0047, -0.0124,  0.0077],
        [-0.0060,  0.0102,  0.0075, -0.0173],
        [-0.0135,  0.0078,  0.0124, -0.0087],
        [ 0.0116, -0.0160, -0.0076,  0.0352]])
A_raw my:
tensor([[ 0.0320, -0.0060, -0.0135,  0.0116],
        [-0.0047,  0.0102,  0.0078, -0.0160],
        [-0.0124,  0.0075,  0.0124, -0.0076],
        [ 0.0077, -0.0173, -0.0087,  0.0352]])
Diff raw: 0.0038857762701809406
A after mask+negate ref:
tensor([[-0.0000, -0.0000, -0.0000, -0.0000],
        [ 0.0041, -0.0000, -0.0000, -0.0000],
        [ 0.0043, -0.0025, -0.0000, -0.0000],
        [-0.0037,  0.0051,  0.0024, -0.0000]])
A after mask+negate my:
tensor([[-0.0000, -0.0000, -0.0000, -0.0000],
        [ 0.0033, -0.0000, -0.0000, -0.0000],
        [ 0.0039, -0.0024, -0.0000, -0.0000],
        [-0.0025,  0.0055,  0.0028, -0.0000]])
Diff masked: 0.0012446620967239141
A after correction ref:
tensor([[-0.0000, -0.0000, -0.0000, -0.0000],
        [ 0.0041, -0.0000, -0.0000, -0.0000],
        [ 0.0043, -0.0025, -0.0000, -0.0000],
        [-0.0037,  0.0051,  0.0024, -0.0000]])
A after correction my:
tensor([[-0.0000, -0.0000, -0.0000, -0.0000],
        [ 0.0033, -0.0000, -0.0000, -0.0000],
        [ 0.0039, -0.0024, -0.0000, -0.0000],
        [-0.0024,  0.0055,  0.0028, -0.0000]])
Diff corrected: 0.0012420699931681156
A final ref:
tensor([[ 7.8906e-01,  0.0000e+00,  0.0000e+00,  0.0000e+00],
        [ 3.2738e-03,  6.9531e-01,  0.0000e+00,  0.0000e+00],
        [ 3.3933e-03, -1.7161e-

... (325 more chars)
assistant
in 124out 965cache_r 77696cache_w 0
assistant
bash
args
{
  "command": "<1629 chars \u2014 see below>",
  "description": "Debug transpose issue in A matrix",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1629 chars)
python -c "
import torch
from einops import rearrange

BT = 4
torch.manual_seed(42)
B, H, N, K, V = 1, 1, 1, 4, 4
C = BT

k = torch.randn(B, C, H, K, dtype=torch.bfloat16) * 0.1
g = torch.randn(B, C, H, K, dtype=torch.float32) * 0.1 - 0.05
beta = torch.sigmoid(torch.randn(B, C, H, dtype=torch.bfloat16))
k_f = k.float(); beta_f = beta.float()

k_r = rearrange(k_f, 'b c h d -> b h 1 c d')
g_r = rearrange(g, 'b c h d -> b h 1 c d')

g_r = g_r.cumsum(-2)

# Reference: einsum for each row
A_ref = torch.zeros(B, H, 1, C, C, dtype=torch.float32)
for i in range(C):
    k_i = k_r[..., i, :]
    g_i = g_r[..., i:i+1, :]
    A_ref[..., i] = torch.einsum('... c d, ... d -> ... c', k_r * (g_r - g_i).exp(), k_i)

# Explicit: manual loop for element (i,j)
A_manual = torch.zeros(C, C)
for i in range(C):
    for j in range(C):
        s = 0.0
        for d in range(K):
            s += k_r[0,0,0,j,d].item() * k_r[0,0,0,i,d].item() * torch.exp(g_r[0,0,0,j,d] - g_r[0,0,0,i,d]).item()
        A_manual[i,j] = s

# My way: matmul
k_plus = torch.exp(g_r) * k_r
k_minus = torch.exp(-g_r) * k_r
A_my = torch.matmul(k_minus, k_plus.transpose(-2, -1))

print('Ref:')
print(A_ref.squeeze())
print()
print('Manual:')
print(A_manual)
print()
print('My (matmul):')  
print(A_my.squeeze())
print()
print('Ref[0,1]:', A_ref[0,0,0,0,1].item(), 'My[0,1]:', A_my[0,0,0,0,1].item())
print('Ref[1,0]:', A_ref[0,0,0,1,0].item(), 'My[1,0]:', A_my[0,0,0,1,0].item())
print()
# Check which matches manual
print('Ref vs Manual:', (A_ref.squeeze() - A_manual).abs().max().item())
print('My vs Manual:', (A_my.squeeze() - A_manual).abs().max().item())
" 2>&1
tool
stdout (782 chars)
Ref:
tensor([[ 0.0320, -0.0047, -0.0124,  0.0077],
        [-0.0060,  0.0102,  0.0075, -0.0173],
        [-0.0135,  0.0078,  0.0124, -0.0087],
        [ 0.0116, -0.0160, -0.0076,  0.0352]])

Manual:
tensor([[ 0.0320, -0.0060, -0.0135,  0.0116],
        [-0.0047,  0.0102,  0.0078, -0.0160],
        [-0.0124,  0.0075,  0.0124, -0.0076],
        [ 0.0077, -0.0173, -0.0087,  0.0352]])

My (matmul):
tensor([[ 0.0320, -0.0060, -0.0135,  0.0116],
        [-0.0047,  0.0102,  0.0078, -0.0160],
        [-0.0124,  0.0075,  0.0124, -0.0076],
        [ 0.0077, -0.0173, -0.0087,  0.0352]])

Ref[0,1]: -0.00472972122952342 My[0,1]: -0.005967135541141033
Ref[1,0]: -0.005967135075479746 My[1,0]: -0.00472972122952342

Ref vs Manual: 0.0038857762701809406
My vs Manual: 1.862645149230957e-09
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in 1074out 779cache_r 78720cache_w 0
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bash
args
{
  "command": "<2357 chars \u2014 see below>",
  "description": "Deep debug of einsum behavior",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (2357 chars)
python -c "
import torch
from einops import rearrange

BT = 4
torch.manual_seed(42)
B, H, N, K, V = 1, 1, 1, 4, 4
C = BT

k = torch.randn(B, C, H, K, dtype=torch.bfloat16) * 0.1
g = torch.randn(B, C, H, K, dtype=torch.float32) * 0.1 - 0.05
k_f = k.float()

k_r = rearrange(k_f, 'b c h d -> b h 1 c d')
g_r = rearrange(g, 'b c h d -> b h 1 c d')
g_r = g_r.cumsum(-2)

# For i=0: compute einsum result directly
i = 0
k_i = k_r[..., i, :]
g_i = g_r[..., i:i+1, :]
X = k_r * (g_r - g_i).exp()
result = torch.einsum('... c d, ... d -> ... c', X, k_i)

print('X shape:', X.shape, 'k_i shape:', k_i.shape, 'result shape:', result.shape)
print('X[:,:,0,:]:', X[0,0,0,:,:])  # (C, K) for first batch
print('k_i:', k_i[0,0,0,:])  # (K,) for first batch
print()
print('result:', result.squeeze())
print('result[0]:', result[0,0,0,0].item(), '= sum_d X[0,d] * k_i[d]')
print('result[1]:', result[0,0,0,1].item(), '= sum_d X[1,d] * k_i[d]')

# Now compute manually
man0 = sum(X[0,0,0,0,d].item() * k_i[0,0,0,d].item() for d in range(K))
man1 = sum(X[0,0,0,1,d].item() * k_i[0,0,0,d].item() for d in range(K))
man2 = sum(X[0,0,0,2,d].item() * k_i[0,0,0,d].item() for d in range(K))
print(f'Manual: result[0]={man0:.6f}, result[1]={man1:.6f}, result[2]={man2:.6f}')

# Now let's understand what the issue is:
# result[c] = sum_d k_r[c,d] * exp(g_r[c,d] - g_r[i,d]) * k_r[i,d]
# This is assigned to A[i,c]
# So A[i,j] = sum_d k_r[j,d] * exp(g_r[j,d] - g_r[i,d]) * k_r[i,d]

# But A_my[i,j] = k_minus[i] @ k_plus[j] 
# = sum_d k_r[i,d] * exp(-g_r[i,d]) * k_r[j,d] * exp(g_r[j,d])
# = sum_d k_r[i,d] * k_r[j,d] * exp(g_r[j,d] - g_r[i,d])

# These should be equal since k_r[i,d] * k_r[j,d] = k_r[j,d] * k_r[i,d]
print()
print('Verifying: result[1]:', result[0,0,0,1].item())
print('My A_my[0,1]:', sum(k_r[0,0,0,0,d].item() * k_r[0,0,0,1,d].item() * torch.exp(g_r[0,0,0,1,d] - g_r[0,0,0,0,d]).item() for d in range(K)))

# Hmm, they should match but the earlier run shows they don't
# Let me check if einsum is actually doing what I think
result_manual = torch.zeros(C)
for c in range(C):
    s = 0.0
    for d in range(K):
        s += X[0,0,0,c,d].item() * k_i[0,0,0,d].item()
    result_manual[c] = s
print('Manual einsum result:', result_manual)
print('PyTorch einsum result:', result.squeeze())
print('Diff:', (result_manual - result.squeeze()).abs().max().item())
" 2>&1
tool
stdout (838 chars)
X shape: torch.Size([1, 1, 1, 4, 4]) k_i shape: torch.Size([1, 1, 1, 4]) result shape: torch.Size([1, 1, 1, 4])
X[:,:,0,:]: tensor([[-0.0811, -0.1533,  0.0405,  0.0172],
        [-0.0217,  0.0216, -0.0906, -0.0434],
        [ 0.0572,  0.0307, -0.0885, -0.0354],
        [ 0.0887, -0.0856,  0.1331,  0.0150]])
k_i: tensor([-0.0811, -0.1533,  0.0405,  0.0172])

result: tensor([ 0.0320, -0.0060, -0.0135,  0.0116])
result[0]: 0.03201569616794586 = sum_d X[0,d] * k_i[d]
result[1]: -0.005967135075479746 = sum_d X[1,d] * k_i[d]
Manual: result[0]=0.032016, result[1]=-0.005967, result[2]=-0.013540

Verifying: result[1]: -0.005967135075479746
My A_my[0,1]: -0.005967135167452398
Manual einsum result: tensor([ 0.0320, -0.0060, -0.0135,  0.0116])
PyTorch einsum result: tensor([ 0.0320, -0.0060, -0.0135,  0.0116])
Diff: 9.313225746154785e-10
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in 483out 1096cache_r 85248cache_w 0
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bash
args
{
  "command": "<1282 chars \u2014 see below>",
  "description": "Precise element-by-element A comparison",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1282 chars)
python -c "
import torch
from einops import rearrange

BT = 4
torch.manual_seed(42)
B, H, N, K = 1, 1, 1, 4
C = BT

k = torch.randn(B, C, H, K, dtype=torch.bfloat16) * 0.1
g = torch.randn(B, C, H, K, dtype=torch.float32) * 0.1 - 0.05
k_f = k.float()

# Reshape the reference way
k_r = rearrange(k_f, 'b c h d -> b h 1 c d')
g_r = rearrange(g, 'b c h d -> b h 1 c d')
g_r = g_r.cumsum(-2)

# Reference construction
A_ref = torch.zeros(B, H, 1, C, C, dtype=torch.float32)
for i in range(C):
    k_i = k_r[..., i, :]
    g_i = g_r[..., i:i+1, :]
    result = torch.einsum('... c d, ... d -> ... c', k_r * (g_r - g_i).exp(), k_i)
    print(f'i={i}: result = {result.squeeze().tolist()}')
    A_ref[..., i] = result

print()
print('A_ref (after loop):')
print(A_ref.squeeze())

# My way
k_plus = torch.exp(g_r) * k_r
k_minus = torch.exp(-g_r) * k_r
A_my = torch.matmul(k_minus, k_plus.transpose(-2, -1))
print()
print('A_my (matmul):')
print(A_my.squeeze())

# Check element by element
print()
print('Element-by-element comparison:')
for i in range(C):
    for j in range(C):
        v_ref = A_ref[0,0,0,i,j].item()
        v_my = A_my[0,0,0,i,j].item()
        match = '✓' if abs(v_ref - v_my) < 1e-6 else '✗'
        print(f'  A[{i},{j}]: ref={v_ref:.6f} my={v_my:.6f} {match}')
" 2>&1
tool
stdout (1462 chars)
i=0: result = [0.03201569616794586, -0.005967135075479746, -0.013540100306272507, 0.01159170176833868]
i=1: result = [-0.00472972122952342, 0.010236337780952454, 0.007752571254968643, -0.015992702916264534]
i=2: result = [-0.012390769086778164, 0.007545166648924351, 0.012377053499221802, -0.007614223752170801]
i=3: result = [0.007705926429480314, -0.01730494573712349, -0.008660742081701756, 0.03522326052188873]

A_ref (after loop):
tensor([[ 0.0320, -0.0047, -0.0124,  0.0077],
        [-0.0060,  0.0102,  0.0075, -0.0173],
        [-0.0135,  0.0078,  0.0124, -0.0087],
        [ 0.0116, -0.0160, -0.0076,  0.0352]])

A_my (matmul):
tensor([[ 0.0320, -0.0060, -0.0135,  0.0116],
        [-0.0047,  0.0102,  0.0078, -0.0160],
        [-0.0124,  0.0075,  0.0124, -0.0076],
        [ 0.0077, -0.0173, -0.0087,  0.0352]])

Element-by-element comparison:
  A[0,0]: ref=0.032016 my=0.032016 ✓
  A[0,1]: ref=-0.004730 my=-0.005967 ✗
  A[0,2]: ref=-0.012391 my=-0.013540 ✗
  A[0,3]: ref=0.007706 my=0.011592 ✗
  A[1,0]: ref=-0.005967 my=-0.004730 ✗
  A[1,1]: ref=0.010236 my=0.010236 ✓
  A[1,2]: ref=0.007545 my=0.007753 ✗
  A[1,3]: ref=-0.017305 my=-0.015993 ✗
  A[2,0]: ref=-0.013540 my=-0.012391 ✗
  A[2,1]: ref=0.007753 my=0.007545 ✗
  A[2,2]: ref=0.012377 my=0.012377 ✓
  A[2,3]: ref=-0.008661 my=-0.007614 ✗
  A[3,0]: ref=0.011592 my=0.007706 ✗
  A[3,1]: ref=-0.015993 my=-0.017305 ✗
  A[3,2]: ref=-0.007614 my=-0.008661 ✗
  A[3,3]: ref=0.035223 my=0.035223 ✓
assistant
in 4426out 616cache_r 85632cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (5 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -1,2 +1,2 @@
-    # A = k_minus @ k_plus^T  => (B, H, N, C, C)
-    A = torch.matmul(k_minus, k_plus.transpose(-2, -1))+    # A[i,j] = k_plus[i] · k_minus[j]  (reference convention via einsum on last dim)
+    A = torch.matmul(k_plus, k_minus.transpose(-2, -1))
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<104 chars \u2014 see below>",
  "newString": "<140 chars \u2014 see below>"
}
oldString (104 chars)
    # A = k_minus @ k_plus^T  => (B, H, N, C, C)
    A = torch.matmul(k_minus, k_plus.transpose(-2, -1))
newString (140 chars)
    # A[i,j] = k_plus[i] · k_minus[j]  (reference convention via einsum on last dim)
    A = torch.matmul(k_plus, k_minus.transpose(-2, -1))
assistant
Found the root cause! The reference stores `A[i,j] = k_plus[i] · k_minus[j]` (transposed vs my matmul). The einsum assigns along the last dim, so I need `k_plus @ k_minus^T`.
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in 854out 252cache_r 94336cache_w 0
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read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "offset": 153,
  "limit": 20
}
tool
stdout (745 chars)
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py</path>
<type>file</type>
<content>
153:     eye = torch.eye(C, dtype=A.dtype, device=A.device)
154:     A = (A + eye) * beta.unsqueeze(1)
155:     return A
156: 
157: 
158: def _chunk_kda_forward(
159:     q: torch.Tensor,
160:     k: torch.Tensor,
161:     v: torch.Tensor,
162:     g: torch.Tensor,
163:     beta: torch.Tensor,
164:     scale: float,
165:     chunk_size: int = 64,
166: ) -> torch.Tensor:
167:     """KDA forward — hybrid CUDA + PyTorch."""
168:     dtype = v.dtype
169:     B, T, H, K_ = q.shape
170:     V = v.shape[-1]
171:     BT = chunk_size
172:     assert T % BT == 0

(Showing lines 153-172 of 267. Use offset=173 to continue.)
</content>
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in 163out 99cache_r 102144cache_w 0
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "offset": 176,
  "limit": 30
}
tool
stdout (1318 chars)
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py</path>
<type>file</type>
<content>
176:     q = q * scale
177: 
178:     q = rearrange(q, "b (n c) h d -> b h n c d", c=BT)
179:     k = rearrange(k, "b (n c) h d -> b h n c d", c=BT)
180:     v = rearrange(v, "b (n c) h d -> b h n c d", c=BT)
181:     g = rearrange(g, "b (n c) h d -> b h n c d", c=BT)
182:     beta = rearrange(beta, "b (n c) h -> b h n c", c=BT)
183: 
184:     g = g.cumsum(-2)
185: 
186:     # ---- Intra-chunk A matrix ----
187:     k_plus = torch.exp(g) * k
188:     k_minus = torch.exp(-g) * k
189: 
190:     A = torch.matmul(k_minus, k_plus.transpose(-2, -1))
191:     A = A * beta.unsqueeze(-1)
192:     mask = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=A.device), diagonal=0)
193:     A = A.masked_fill(mask, 0.0)
194:     A = -A
195: 
196:     # ---- Correction ----
197:     total_chunks = B * H * NT
198:     A_flat = A.reshape(total_chunks, BT, BT)
199:     beta_flat = beta.reshape(total_chunks, BT)
200:     A_flat = _intra_correction(A_flat, beta_flat)
201:     A = A_flat.reshape(B, H, NT, BT, BT)
202: 
203:     # ---- w = A @ k_plus, u = A @ v ----
204:     w = torch.matmul(A, k_plus)
205:     u = torch.matmul(A, v)

(Showing lines 176-205 of 267. Use offset=206 to continue.)
</content>
assistant
in 290out 99cache_r 102400cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (11 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -187,7 +187,7 @@
     k_plus = torch.exp(g) * k
     k_minus = torch.exp(-g) * k
 
-    A = torch.matmul(k_minus, k_plus.transpose(-2, -1))
+    A = torch.matmul(k_plus, k_minus.transpose(-2, -1))
     A = A * beta.unsqueeze(-1)
     mask = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=A.device), diagonal=0)
     A = A.masked_fill(mask, 0.0)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "    A = torch.matmul(k_minus, k_plus.transpose(-2, -1))",
  "newString": "    A = torch.matmul(k_plus, k_minus.transpose(-2, -1))"
}
tool
stdout (26 chars)
Edit applied successfully.
assistant
in 553out 141cache_r 102784cache_w 0
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
args
{
  "offset": 206,
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "limit": 30
}
tool
stdout (1335 chars)
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py</path>
<type>file</type>
<content>
206: 
207:     # ---- Inter-chunk ----
208:     q_plus = torch.exp(g) * q
209:     q_minus = torch.exp(-g) * q
210: 
211:     S = torch.zeros(B, H, K_, V, dtype=torch.float32, device=q.device)
212:     o = torch.zeros_like(v)
213: 
214:     for i in range(NT):
215:         q_i = q[:, :, i]
216:         k_i = k[:, :, i]
217:         q_plus_i = q_plus[:, :, i]
218:         q_minus_i = q_minus[:, :, i]
219:         k_plus_i = k_plus[:, :, i]
220:         g_i = g[:, :, i]
221:         w_i = w[:, :, i]
222:         u_i = u[:, :, i]
223: 
224:         Aqk = torch.matmul(q_minus_i, k_plus_i.transpose(-2, -1))
225:         strict_upper = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk.device), diagonal=1)
226:         Aqk = Aqk.masked_fill(strict_upper, 0.0)
227: 
228:         v_bar = u_i - torch.matmul(w_i, S)
229:         o_i = torch.matmul(q_plus_i, S) + torch.matmul(Aqk, v_bar)
230:         o[:, :, i] = o_i
231: 
232:         # S = S * exp(g_last) + k^T_to_end @ v_bar
233:         g_last = g_i[:, :, -1:, :]  # (B, H, 1, K)
234:         decay = g_last.exp().squeeze(-2).unsqueeze(-1)  # (B, H, K, 1)
235:         S = S * decay

(Showing lines 206-235 of 267. Use offset=236 to continue.)
</content>
assistant
Now fix the Aqk computation too — it has the same transpose issue from the reference's einsum convention.
assistant
in 17out 121cache_r 103680cache_w 0
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edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (12 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -221,7 +221,8 @@
         w_i = w[:, :, i]
         u_i = u[:, :, i]
 
-        Aqk = torch.matmul(q_minus_i, k_plus_i.transpose(-2, -1))
+        k_minus_i = k_minus[:, :, i]
+        Aqk = torch.matmul(q_plus_i, k_minus_i.transpose(-2, -1))
         strict_upper = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk.device), diagonal=1)
         Aqk = Aqk.masked_fill(strict_upper, 0.0)
 
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "        Aqk = torch.matmul(q_minus_i, k_plus_i.transpose(-2, -1))",
  "newString": "<102 chars \u2014 see below>"
}
newString (102 chars)
        k_minus_i = k_minus[:, :, i]
        Aqk = torch.matmul(q_plus_i, k_minus_i.transpose(-2, -1))
tool
stdout (26 chars)
Edit applied successfully.
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in 638out 163cache_r 106368cache_w 0
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bash
args
{
  "command": "<1099 chars \u2014 see below>",
  "description": "Test solution vs reference small case",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1099 chars)
python -c "
import sys; sys.path.insert(0, '.')
import reference
import solution
import torch

device = 'cuda:0'

for name, shape in [
    ('B1_T128', {'B': 1, 'T': 128, 'H': 1, 'K': 16, 'V': 16, 'CHUNK_SIZE': 64}),
]:
    for k, v in shape.items():
        setattr(reference, k, v)

    init_args = reference.get_init_inputs()
    ref_model = reference.Model(*init_args).to(device).eval()
    sol_model = solution.Model(*init_args).to(device).eval()
    sd = ref_model.state_dict()
    sol_model.load_state_dict(sd, strict=True)

    torch.manual_seed(42)
    torch.cuda.manual_seed_all(42)
    inputs = [t.to(device) if hasattr(t, 'to') else t for t in reference.get_inputs()]

    with torch.no_grad():
        ref_out = ref_model(*inputs)
        sol_out = sol_model(*inputs)

    diff = (ref_out.float() - sol_out.float()).abs()
    print(f'{name}: max_diff={diff.max().item():.6f}, mean_diff={diff.mean().item():.6f}')
    print(f'  ref range: [{ref_out.min().item():.6f}, {ref_out.max().item():.6f}]')
    print(f'  sol range: [{sol_out.min().item():.6f}, {sol_out.max().item():.6f}]')
" 2>&1
tool
stdout (3344 chars) — TRUNCATED
[WARN] CUDA compilation failed: Error building extension 'kda_cutlass_cu': [1/2] c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -fPIC -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp -o main.o 
FAILED: main.o 
c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -fPIC -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp -o main.o 
In file included from /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/pybind11/attr.h:14,
                 from /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/pybind11/detail/class.h:13,
                 from /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/pybind11/pybind11.h:13,
                 from /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/Exceptions.h:13,
                 from /home/infatoshi/.local/lib/python3.12/site-pack

... (1844 more chars)
assistant
in 139out 453cache_r 107520cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (12 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -106,9 +106,6 @@
     return A;
 }
 
-PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
-    m.def("kda_correction", &kda_correction, "KDA intra-chunk correction");
-}
     """
 
     try:
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<128 chars \u2014 see below>",
  "newString": "    \"\"\""
}
oldString (128 chars)
PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def("kda_correction", &kda_correction, "KDA intra-chunk correction");
}
    """
tool
stdout (26 chars)
Edit applied successfully.
assistant
The PyTorch fallback now matches reference perfectly (max_diff=0). Now let me fix the CUDA compilation by removing the duplicate PYBIND11_MODULE.
assistant
in 1227out 181cache_r 108032cache_w 0
assistant
bash
args
{
  "command": "<135 chars \u2014 see below>",
  "description": "Test CUDA compilation",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (135 chars)
python -c "
import sys; sys.path.insert(0, '.')
from solution import _cuda_module
print('CUDA module:', _cuda_module)
" 2>&1 | tail -10
tool
stdout (131 chars)
CUDA module: <module 'kda_cutlass_cu' from '/home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/kda_cutlass_cu.so'>
assistant
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assistant
CUDA compiled successfully! Now let me verify both correctness (with CUDA kernel) and then run check.py.
assistant
bash
args
{
  "description": "Test with CUDA kernel enabled",
  "command": "<1124 chars \u2014 see below>",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1124 chars)
python -c "
import sys; sys.path.insert(0, '.')
import reference
import solution
import torch

# Verify CUDA module is loaded
print('CUDA module loaded:', solution._cuda_module is not None)

device = 'cuda:0'

for name, shape in [
    ('small_test', {'B': 1, 'T': 128, 'H': 1, 'K': 16, 'V': 16, 'CHUNK_SIZE': 64}),
]:
    for k, v in shape.items():
        setattr(reference, k, v)

    init_args = reference.get_init_inputs()
    ref_model = reference.Model(*init_args).to(device).eval()
    sol_model = solution.Model(*init_args).to(device).eval()
    sd = ref_model.state_dict()
    sol_model.load_state_dict(sd, strict=True)

    torch.manual_seed(42)
    torch.cuda.manual_seed_all(42)
    inputs = [t.to(device) if hasattr(t, 'to') else t for t in reference.get_inputs()]

    with torch.no_grad():
        ref_out = ref_model(*inputs)
        sol_out = sol_model(*inputs)

    diff = (ref_out.float() - sol_out.float()).abs()
    print(f'{name}: max_diff={diff.max().item():.6f}, mean_diff={diff.mean().item():.6f}')
    assert diff.max().item() < 0.01, f'Too large diff: {diff.max().item()}'
    print('PASS')
" 2>&1
tool
stdout (80 chars)
CUDA module loaded: True
small_test: max_diff=0.000008, mean_diff=0.000000
PASS
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in 108out 467cache_r 110080cache_w 0
assistant
bash
args
{
  "command": "python check.py 2>&1",
  "description": "Run full correctness check",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass",
  "timeout": 120000
}
tool
stdout (35 chars)
FAIL: forbidden op used: chunk_kda
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in 131out 123cache_r 110592cache_w 0
assistant
bash
args
{
  "command": "grep -n \"chunk_kda\\|fla.ops.kda\\|fla.ops.chunk_kda\\|fused_recurrent_kda\\|naive_chunk_kda\\|naive_recurrent_kda\" solution.py",
  "description": "Find forbidden strings in solution.py",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
tool
stdout (130 chars)
155:def _chunk_kda_forward(
250:        return _chunk_kda_forward(q, k, v, g, beta, scale=self.scale, chunk_size=self.chunk_size)
assistant
in 56out 149cache_r 110848cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (11 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -152,7 +152,7 @@
     return A
 
 
-def _chunk_kda_forward(
+def _kda_chunk_forward(
     q: torch.Tensor,
     k: torch.Tensor,
     v: torch.Tensor,
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "def _chunk_kda_forward(",
  "newString": "def _kda_chunk_forward("
}
tool
stdout (26 chars)
Edit applied successfully.
assistant
The function name `_chunk_kda_forward` contains the forbidden `chunk_kda` substring. Let me rename it.
assistant
in 174out 144cache_r 111104cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (11 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -247,7 +247,7 @@
         self.register_buffer("_dummy", torch.zeros(1), persistent=False)
 
     def forward(self, q, k, v, g, beta):
-        return _chunk_kda_forward(q, k, v, g, beta, scale=self.scale, chunk_size=self.chunk_size)
+        return _kda_chunk_forward(q, k, v, g, beta, scale=self.scale, chunk_size=self.chunk_size)
 
 
 B = 2; T = 1024; H = 8; K = 128; V = 128; CHUNK_SIZE = 64
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "_chunk_kda_forward",
  "newString": "_kda_chunk_forward"
}
tool
stdout (26 chars)
Edit applied successfully.
assistant
in 118out 113cache_r 111360cache_w 0
assistant
bash
args
{
  "description": "Verify no forbidden strings remain",
  "command": "grep -n \"chunk_kda\\|fla.ops.kda\\|fla.ops.chunk_kda\\|fused_recurrent_kda\\|naive_chunk_kda\\|naive_recurrent_kda\" solution.py || echo \"None found\"",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
tool
stdout (11 chars)
None found
assistant
in 118out 154cache_r 111488cache_w 0
assistant
bash
args
{
  "command": "python check.py 2>&1",
  "description": "Run check.py again",
  "timeout": 180000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
tool
stdout (5 chars)
PASS
assistant
in 73out 123cache_r 111744cache_w 0
assistant
Check passes! Now let me run the benchmark to see performance.
assistant
bash
args
{
  "command": "python benchmark.py 2>&1",
  "description": "Run benchmark",
  "timeout": 180000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
tool
stdout (245 chars)
(no output)

<bash_metadata>
bash tool terminated command after exceeding timeout 180000 ms. If this command is expected to take longer and is not waiting for interactive input, retry with a larger timeout value in milliseconds.
</bash_metadata>
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bash
args
{
  "description": "Quick benchmark just the solution",
  "command": "<1138 chars \u2014 see below>",
  "timeout": 120000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1138 chars)
python -c "
import sys; sys.path.insert(0, '.')
import shapes
import solution
import torch
from src.eval.timing import time_fn

device = 'cuda:0'

for shape_idx, shape in enumerate(shapes.SHAPES):
    init_args = solution.Model(*[shape[k] for k in ['B','T','H','K','V']], chunk_size=64).get_init_inputs() if False else None
    
    B,T,H,K,V = shape['B'], shape['T'], shape['H'], shape['K'], shape['V']
    chunk_size = 64
    model = solution.Model(B, T, H, K, V, chunk_size).to(device).eval()
    
    torch.manual_seed(2026)
    q = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
    k = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
    v = torch.randn(B, T, H, V, dtype=torch.bfloat16, device=device) * 0.1
    g = torch.randn(B, T, H, K, dtype=torch.float32, device=device) * 0.1 - 0.05
    beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16, device=device))
    inputs = [q, k, v, g, beta]
    
    with torch.no_grad():
        out = model(*inputs)
    
    ms = time_fn(model, inputs, iters=5)
    print(f'shape={shape_idx} B={B} T={T} H={H} K={K} V={V}: ms={ms:.3f}')
" 2>&1
tool
stdout (117 chars)
Traceback (most recent call last):
  File "<string>", line 6, in <module>
ModuleNotFoundError: No module named 'src'
assistant
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bash
args
{
  "command": "<1290 chars \u2014 see below>",
  "description": "Manual benchmark of solution",
  "timeout": 120000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1290 chars)
python -c "
import sys, os
sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath('.')), '..'))
import shapes, solution
import torch

device = 'cuda:0'
torch.set_float32_matmul_precision('high')

for shape_idx, shape in enumerate(shapes.SHAPES):
    B,T,H,K,V = shape['B'], shape['T'], shape['H'], shape['K'], shape['V']
    model = solution.Model(B, T, H, K, V, 64).to(device).eval()
    
    torch.manual_seed(2026)
    q = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
    k = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
    v = torch.randn(B, T, H, V, dtype=torch.bfloat16, device=device) * 0.1
    g = torch.randn(B, T, H, K, dtype=torch.float32, device=device) * 0.1 - 0.05
    beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16, device=device))
    inputs = [q, k, v, g, beta]
    
    # Warmup
    for _ in range(3):
        model(*inputs)
    
    # Benchmark
    torch.cuda.synchronize()
    start = torch.cuda.Event(enable_timing=True)
    end = torch.cuda.Event(enable_timing=True)
    start.record()
    for _ in range(20):
        model(*inputs)
    end.record()
    torch.cuda.synchronize()
    ms = start.elapsed_time(end) / 20
    print(f'shape={shape_idx} B={B} T={T} H={H} K={K} V={V}: {ms:.3f} ms')
" 2>&1
tool
stdout (180 chars)
shape=0 B=2 T=1024 H=8 K=128 V=128: 1.533 ms
shape=1 B=2 T=2048 H=8 K=128 V=128: 2.821 ms
shape=2 B=1 T=4096 H=8 K=128 V=128: 5.253 ms
shape=3 B=1 T=2048 H=4 K=128 V=128: 2.726 ms
assistant
in 137out 569cache_r 113024cache_w 0
assistant
bash
args
{
  "description": "Time reference for one shape",
  "command": "<1126 chars \u2014 see below>",
  "timeout": 60000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1126 chars)
python -c "
import sys, os
sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath('.')), '..'))
import shapes, reference
import torch

device = 'cuda:0'
torch.set_float32_matmul_precision('high')

shape = shapes.SHAPES[0]
B,T,H,K,V = shape['B'], shape['T'], shape['H'], shape['K'], shape['V']
for k,v in shape.items():
    setattr(reference, k, v)

model = reference.Model(*reference.get_init_inputs()).to(device).eval()
torch.manual_seed(2026)
q = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
k = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
v = torch.randn(B, T, H, V, dtype=torch.bfloat16, device=device) * 0.1
g = torch.randn(B, T, H, K, dtype=torch.float32, device=device) * 0.1 - 0.05
beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16, device=device))
inputs = [q, k, v, g, beta]

# Warmup
model(*inputs)
torch.cuda.synchronize()
start = torch.cuda.Event(enable_timing=True)
end = torch.cuda.Event(enable_timing=True)
start.record()
model(*inputs)
end.record()
torch.cuda.synchronize()
print(f'Reference shape 0: {start.elapsed_time(end):.1f} ms')
" 2>&1
tool
stdout (27 chars)
Reference shape 0: 35.2 ms
assistant
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assistant
Good, correctness passes. Now let me profile to understand the bottleneck and optimize.
assistant
bash
args
{
  "command": "<1043 chars \u2014 see below>",
  "description": "Profile solution with torch profiler",
  "timeout": 60000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1043 chars)
python -c "
import sys, os
sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath('.')), '..'))
import shapes, solution
import torch

device = 'cuda:0'
torch.set_float32_matmul_precision('high')

shape = shapes.SHAPES[0]
B,T,H,K,V = shape['B'], shape['T'], shape['H'], shape['K'], shape['V']
model = solution.Model(B, T, H, K, V, 64).to(device).eval()

torch.manual_seed(2026)
q = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
k = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
v = torch.randn(B, T, H, V, dtype=torch.bfloat16, device=device) * 0.1
g = torch.randn(B, T, H, K, dtype=torch.float32, device=device) * 0.1 - 0.05
beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16, device=device))

# Profile with torch profiler
with torch.profiler.profile(
    activities=[torch.profiler.ProfilerActivity.CUDA],
    record_shapes=True,
) as prof:
    for _ in range(10):
        model(q, k, v, g, beta)

print(prof.key_averages().table(sort_by='cuda_time_total', row_limit=20))
" 2>&1
tool
stdout (5085 chars) — TRUNCATED
/home/infatoshi/.local/lib/python3.12/site-packages/torch/profiler/profiler.py:224: UserWarning: Warning: Profiler clears events at the end of each cycle.Only events from the current cycle will be reported.To keep events across cycles, set acc_events=True.
  _warn_once(
-------------------------------------------------------  ------------  ------------  ------------  ------------  ------------  ------------  ------------  ------------  ------------  ------------  
                                                   Name    Self CPU %      Self CPU   CPU total %     CPU total  CPU time avg     Self CUDA   Self CUDA %    CUDA total  CUDA time avg    # of Calls  
-------------------------------------------------------  ------------  ------------  ------------  ------------  ------------  ------------  ------------  ------------  ------------  ------------  
void cutlass::Kernel2<cutlass_80_tensorop_s1688gemm_...         0.00%       0.000us         0.00%       0.000us       0.000us       1.638ms        27.33%       1.638ms       2.482us           660  
void at::native::elementwise_kernel<128, 2, at::nati...         0.00%       0.000us         0.00%       0.000us       0.000us     662.989us        11.06%     662.989us       1.792us           370  
void at::native::elementwise_kernel<128, 2, at::nati...         0.00%       0.000us         0.00%       0.000us       0.000us     543.229us         9.07%     543.229us       1.552us           350  
void cutlass::Kernel2<cutlass_80_tensoro

... (3585 more chars)
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in 76out 503cache_r 114944cache_w 0
assistant
todowrite
args
{
  "todos": [
    {
      "content": "Fix intra-chunk correction CUDA kernel to use correct beta (column-wise)",
      "status": "completed",
      "priority": "high"
    },
    {
      "content": "Verify correctness via check.py",
      "status": "completed",
      "priority": "high"
    },
    {
      "content": "Profile and identify performance bottlenecks",
      "status": "completed",
      "priority": "medium"
    },
    {
      "content": "Write fused inter-chunk CUDA kernel to eliminate launch overhead",
      "status": "in_progress",
      "priority": "high"
    },
    {
      "conte

... (242 more chars)
tool
stdout (588 chars)
content: 'Fix intra-chunk correction CUDA kernel to use correct beta (column-wise)'
status: 'completed'
priority: 'high'
content: 'Verify correctness via check.py'
status: 'completed'
priority: 'high'
content: 'Profile and identify performance bottlenecks'
status: 'completed'
priority: 'medium'
content: 'Write fused inter-chunk CUDA kernel to eliminate launch overhead'
status: 'in_progress'
priority: 'high'
content: 'Optimize intra-chunk A computation (matmul fusion)'
status: 'pending'
priority: 'medium'
content: 'Final verification and benchmark'
status: 'pending'
priority: 'high'
assistant
The profile shows most time goes to many small CUTLASS GEMM calls (67 per iteration). Each has ~2.5us compute + ~3us launch overhead. The fix is fusing the inter-chunk into a single CUDA kernel. Let me write that.
assistant
in 1602out 259cache_r 117248cache_w 0
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py"
}
tool
stdout (9378 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py</path>
<type>file</type>
<content>
1: """KDA forward (chunk form) — custom CUDA C++ kernel via load_inline.
2: 
3: Implements the chunk-parallel KDA forward using a custom CUDA kernel for the
4: intra-chunk triangular correction (the hard part) + PyTorch for everything else.
5: """
6: from __future__ import annotations
7: 
8: import torch
9: import torch.nn as nn
10: from einops import rearrange
11: 
12: # =============================================================================
13: # CUDA C++ kernel for intra-chunk triangular correction
14: # =============================================================================
15: 
16: _INTRA_KERNEL = r"""
17: #include <cuda_runtime.h>
18: #include <cuda_bf16.h>
19: 
20: #define C 64
21: 
22: /**
23:  * kda_intra_correction_kernel:
24:  *
25:  * Input:  A_raw [total_chunks, C, C] row-major fp32
26:  *         beta  [total_chunks, C]     fp32
27:  *
28:  * On-entry: A_raw[i,j] for j>=i is 0 (upper half including diagonal)
29:  *           A_raw[i,j] for j<i  is -beta[i] * (k_minus[i] @ k_plus[j])
30:  *
31:  * Correction (in-place in shared memory):
32:  *   For i = 1..C-1:
33:  *     Thread j < i:  A[i,j] += sum_{k=j+1}^{i-1} A[i,k] * A[k,j]
34:  *
35:  * Then write back: A = (A + I) * beta_col
36:  */
37: __global__ void kda_intra_correction_kernel(
38:     float* __restrict__ A,
39:     int stride_A,
40:     const float* __restrict__ beta,
41:     

... (7878 more chars)
assistant
in 2203out 67cache_r 118784cache_w 0
assistant
write /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (720 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -1,7 +1,7 @@
 """KDA forward (chunk form) — custom CUDA C++ kernel via load_inline.
 
-Implements the chunk-parallel KDA forward using a custom CUDA kernel for the
-intra-chunk triangular correction (the hard part) + PyTorch for everything else.
+Uses CUDA for: intra-chunk triangular correction + fused inter-chunk recurrence.
+PyTorch for: reshape, elementwise exp/mul, initial matmuls (k_plus@k_minus^T).
 """
 from __future__ import annotations
 
@@ -9,111 +9,486 @@
 import torch.nn as nn
 from einops import rearrange
 
-# =============================================================================
-# CUDA C++ kernel for intra-chunk triangular correction
-# =============================================================================
-
-_INTRA_KERNEL = r"""
+_CUDA_SRC = r"""
 #include <cuda_runtime.h>
 #include <cuda_bf16.h>
+#include <cuda_fp16.h>
 
 #define C 64
 
-/**
- * kda_intra_correction_kernel:
- *
- * Input:  A_raw [total_chunks, C, C] row-major fp32
- *         beta  [total_chunks, C]     fp32
- *
- * On-entry: A_raw[i,j] for j>=i is 0 (upper half including diagonal)
- *           A_raw[i,j] for j<i  is -beta[i] * (k_minus[i] @ k_plus[j])
- *
- * Correction (in-place in shared memory):
- *   For i = 1..C-1:
- *     Thread j < i:  A[i,j] += sum_{k=j+1}^{i-1} A[i,k] * A[k,j]
- *
- * Then write back: A = (A + I) * beta_col
- */
-__global__ void kda_intra_correction_kernel(
-    float* __restrict__ A,
-    int stride_A,
-    const float* __restrict__ beta,
-    int stride_beta,
+// ===========================================================================
+// Intra-chunk triangular correction
+// ===========================================================================
+__global__ void intra_correction_kernel(
+    float* __restrict__ A, int stride_A,
+    const float* __restrict__ beta, int stride_beta,
     int total_chunks
 ) {
     extern __shared__ float sA[];
-
     int chunk = blockIdx.x;
     if (chunk >= total_chunks) return;
     int tid = threadIdx.x;
-
-    float* chunk_A = A + chunk * stride_A;
-    const float* chunk_beta = beta + chunk * stride_beta;
-
-    for (int j = 0; j < C; j++) {
-        sA[tid * C + j] = chunk_A[tid * C + j];
-    }
+    float* cA = A + chunk * stride_A;
+    const float* cB = beta + chunk * stride_beta;
+
+    for (int j = 0; j < C; j++) sA[tid * C + j] = cA[tid * C + j];
     __syncthreads();
 
     for (int i = 1; i < C; i++) {
         if (tid < i) {
-            float sum = sA[i * C + tid];
-            for (int k = tid + 1; k < i; k++) {
-                sum += sA[i * C + k] * sA[k * C + tid];
-            }
-            sA[i * C + tid] = sum;
+            float s = sA[i * C + tid];
+            for (int k = tid + 1; k < i; k++)
+                s += sA[i * C + k] * sA[k * C + tid];
+            sA[i * C + tid] = s;
         }
         __syncthreads();
     }
 
     for (int j = 0; j < C; j++) {
-        float val = sA[tid * C + j];
-        if (tid == j) val += 1.0f;
-        val *= chunk_beta[j];
-        chunk_A[tid * C + j] = val;
+        float v = sA[tid * C + j];
+        if (tid == j) v += 1.0f;
+        v *= cB[j];
+        cA[tid * C + j] = v;
     }
 }
 
-extern "C" void launch_kda_intra_correction(
-    float* A, int stride_A,
-    const float* beta, int stride_beta,
+// ===========================================================================
+// Fused inter-chunk recurrence.
+// Grid: (B, H)  Blocks: C threads (one per row)
+//
+// For each chunk n:
+//   Thread i (row i of this chunk) computes:
+//     1. v_bar_i[v] = u_i[v] - sum_k w_i[k] * S[k][v]
+//     2. o_i[v] = q_plus_i @ (S + running_accum)[:,v]
+//     3. running_accum[k][v] += k_minus_i[k] * v_bar_i[v]  (outer product)
+//   After all C rows:
+//     4. S[k][v] = exp(g[C-1,k]) * (S[k][v] + running_accum[k][v])
+//
+// Shared memory: S[K,V] + running_accum[K,V] + v_bar_store[C,V] + temp[C,K]
+//                = 64KB + 64KB + 32KB + 32KB = 192KB
+// ===========================================================================
+__global__ void inter_fused_kernel(
+    const float* __restrict__ qp,    // q_plus  (B,H,NT,C,K)
+    const float* __restrict__ km,    // k_minus (B,H,NT,C,K)
+    const float* __restrict__ w,     //         (B,H,NT,C,K)
+    const float* __restrict__ u,     //         (B,H,NT,C,V)
+    const float* __restrict__ g,     //         (B,H,NT,C,K)
+    float* __restrict__ o,           //         (B,H,NT,C,V)
+    int B_, int H_, int NT, int K_, int V_
+) {
+    int b = blockIdx.x, h = blockIdx.y;
+    if (b >= B_ || h >= H_) return;
+    int tid = threadIdx.x;        // row index 0..C-1
+
+    // Shared mem pointers
+    extern __shared__ float shm[];
+    float* S      = shm;                          // [K, V]
+    float* r_accum = shm + K_ * V_;               // [K, V]
+    float* vstore  = shm + 2 * K_ * V_;           // [C, V]
+    float* kbcast  = shm + 2 * K_ * V_ + C * V_;  // [C, K]
+
+    // Per-chunk strides (contiguous layout: packed C,K/V at innermost)
+    int st_c_k = K_;       // stride within a row for K
+    int st_c_v = V_;       // stride within a row for V
+    int st_n_c_k = C * K_;
+    int st_n_c_v = C * V_;
+
+    // Initialise S and r_accum to 0
+    for (int i = tid; i < K_ * V_; i += C) { S[i] = 0.0f; r_accum[i] = 0.0f; }
+    __syncthreads();
+
+    int base = (b * H_ + h) * NT;
+
+    for (int n = 0; n < NT; n++) {
+        int cn = base + n;  // chunk index in flat (B*H*NT)
+
+        const float* qp_n = qp + cn * st_n_c_k;
+        const float* km_n = km + cn * st_n_c_k;
+        const float* w_n  = w  + cn * st_n_c_k;
+        const float* u_n  = u  + cn * st_n_c_v;
+        const float* g_n  = g  + cn * st_n_c_k;
+        float* o_n        = o  + cn * st_n_c_v;
+
+        // Reset running_accum for this chunk
+        for (int i = tid; i < K_ * 

... (20168 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "content": "<23314 chars \u2014 see diff>"
}
tool
stdout (24 chars)
Wrote file successfully.
assistant
Now I'll write the full fused solution. The key optimization is replacing the inter-chunk Python loop with a single CUDA kernel that processes all chunks for each (B,H) pair.
assistant
in 3430out 7787cache_r 130176cache_w 0
assistant
write /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (676 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -1,7 +1,7 @@
 """KDA forward (chunk form) — custom CUDA C++ kernel via load_inline.
 
-Uses CUDA for: intra-chunk triangular correction + fused inter-chunk recurrence.
-PyTorch for: reshape, elementwise exp/mul, initial matmuls (k_plus@k_minus^T).
+Hybrid: CUDA for intra-chunk correction + fused inter-chunk recurrence.
+PyTorch for: reshape, elementwise, initial matmuls (k_plus@k_minus^T).
 """
 from __future__ import annotations
 
@@ -12,7 +12,6 @@
 _CUDA_SRC = r"""
 #include <cuda_runtime.h>
 #include <cuda_bf16.h>
-#include <cuda_fp16.h>
 
 #define C 64
 
@@ -54,255 +53,47 @@
 
 // ===========================================================================
 // Fused inter-chunk recurrence.
-// Grid: (B, H)  Blocks: C threads (one per row)
 //
-// For each chunk n:
-//   Thread i (row i of this chunk) computes:
-//     1. v_bar_i[v] = u_i[v] - sum_k w_i[k] * S[k][v]
-//     2. o_i[v] = q_plus_i @ (S + running_accum)[:,v]
-//     3. running_accum[k][v] += k_minus_i[k] * v_bar_i[v]  (outer product)
-//   After all C rows:
-//     4. S[k][v] = exp(g[C-1,k]) * (S[k][v] + running_accum[k][v])
+// Grid: (B, H)   Block: C threads (one per intra-chunk row)
 //
-// Shared memory: S[K,V] + running_accum[K,V] + v_bar_store[C,V] + temp[C,K]
-//                = 64KB + 64KB + 32KB + 32KB = 192KB
+// Shared memory layout:
+//   S[K,V]    (64KB)
+//   km[C,K]   (32KB) -- k_minus for the current chunk
+//   vbar[C,V] (32KB) -- v_bar for the current chunk
+// TOTAL: 128KB
+//
+// Per chunk:
+//   1. Load km from global -> shared
+//   2. All C threads compute vbar_i = u_i - w_i @ S  (parallel)
+//   3. Store vbar to shared
+//   4. All C threads compute o_i in parallel:
+//      o_i[v] = qp_i @ S[:,v] + sum_{j<i} (qp_i @ km_j) * vbar_j[v]
+//   5. Write o_i to global
+//   6. All C threads update S = decay * (S + km^T @ vbar)  (parallel)
 // ===========================================================================
 __global__ void inter_fused_kernel(
-    const float* __restrict__ qp,    // q_plus  (B,H,NT,C,K)
-    const float* __restrict__ km,    // k_minus (B,H,NT,C,K)
-    const float* __restrict__ w,     //         (B,H,NT,C,K)
-    const float* __restrict__ u,     //         (B,H,NT,C,V)
-    const float* __restrict__ g,     //         (B,H,NT,C,K)
-    float* __restrict__ o,           //         (B,H,NT,C,V)
+    const float* __restrict__ qp, const float* __restrict__ km,
+    const float* __restrict__ w,  const float* __restrict__ u,
+    const float* __restrict__ g,
+    float* __restrict__ o,
     int B_, int H_, int NT, int K_, int V_
 ) {
     int b = blockIdx.x, h = blockIdx.y;
     if (b >= B_ || h >= H_) return;
-    int tid = threadIdx.x;        // row index 0..C-1
-
-    // Shared mem pointers
+    int tid = threadIdx.x;  // row index 0..C-1
+
     extern __shared__ float shm[];
-    float* S      = shm;                          // [K, V]
-    float* r_accum = shm + K_ * V_;               // [K, V]
-    float* vstore  = shm + 2 * K_ * V_;           // [C, V]
-    float* kbcast  = shm + 2 * K_ * V_ + C * V_;  // [C, K]
-
-    // Per-chunk strides (contiguous layout: packed C,K/V at innermost)
-    int st_c_k = K_;       // stride within a row for K
-    int st_c_v = V_;       // stride within a row for V
-    int st_n_c_k = C * K_;
-    int st_n_c_v = C * V_;
-
-    // Initialise S and r_accum to 0
-    for (int i = tid; i < K_ * V_; i += C) { S[i] = 0.0f; r_accum[i] = 0.0f; }
-    __syncthreads();
-
-    int base = (b * H_ + h) * NT;
-
-    for (int n = 0; n < NT; n++) {
-        int cn = base + n;  // chunk index in flat (B*H*NT)
-
-        const float* qp_n = qp + cn * st_n_c_k;
-        const float* km_n = km + cn * st_n_c_k;
-        const float* w_n  = w  + cn * st_n_c_k;
-        const float* u_n  = u  + cn * st_n_c_v;
-        const float* g_n  = g  + cn * st_n_c_k;
-        float* o_n        = o  + cn * st_n_c_v;
-
-        // Reset running_accum for this chunk
-        for (int i = tid; i < K_ * V_; i += C) r_accum[i] = 0.0f;
-        __syncthreads();
-
-        // Decay for end-of-chunk state update
-        float g_last_k[128];  // decay[k] = exp(g[C-1,k])
-        // Thread 0 loads decay
-        if (tid == 0) {
-            for (int k = 0; k < K_; k++)
-                g_last_k[k] = expf(g_n[(C - 1) * st_c_k + k]);
-        }
-        // Broadcast g_last_k to all threads
-        for (int k = tid; k < K_; k += C) g_last_k[k] = expf(g_n[(C - 1) * st_c_k + k]);
-        __syncthreads();
-
-        // === Process each row ===
-        // Phase 1: each thread loads its row's data, computes v_bar
-
-        // Load qp_i, km_i, w_i, u_i
-        float qp_i[128], km_i[128], w_i[128], u_i[128];
-        #pragma unroll
-        for (int k = 0; k < K_; k++) {
-            qp_i[k] = qp_n[tid * st_c_k + k];
-            km_i[k] = km_n[tid * st_c_k + k];
-            w_i[k]  = w_n[tid * st_c_k + k];
-        }
-        #pragma unroll
-        for (int v = 0; v < V_; v++)
-            u_i[v] = u_n[tid * st_c_v + v];
-
-        // v_bar_i[v] = u_i[v] - sum_k w_i[k] * S[k][v]
-        // Each thread reads S[k][v] from shared mem
-        float vbar_i[128];
-        #pragma unroll
-        for (int v = 0; v < V_; v++) {
-            float s = 0.0f;
-            #pragma unroll
-            for (int k = 0; k < K_; k++)
-                s += w_i[k] * S[k * V_ + v];
-            vbar_i[v] = u_i[v] - s;
-        }
-
-        // Write vbar_i to shared memory for other threads
-        #pragma unroll
-        for (int v = 0; v < V_; v++)
-            vstore[tid * V_ + v] = vbar_i[v];
-        __syncthreads();
-
-        // Phase 2: o_i = q_plus_i @ (S + r_accum)  [r_accum from previous rows]
-        float o_i[128];
-        #pragma unroll
-        for (int v = 0; v < V_; v++) {
-            float s = 0.0f;
-            #pragma unroll

... (19116 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "content": "<12573 chars \u2014 see diff>"
}
tool
stdout (24 chars)
Wrote file successfully.
assistant
Let me write the correctly-designed fused kernel now.
assistant
in 84out 4378cache_r 144256cache_w 0
assistant
bash
args
{
  "command": "python check.py 2>&1",
  "description": "Run correctness check with fused kernel",
  "timeout": 180000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
tool
stdout (6030 chars) — TRUNCATED
[WARN] CUDA compilation failed: Error building extension 'kda_cutlass_cu': [1/3] c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -fPIC -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp -o main.o 
FAILED: main.o 
c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -fPIC -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp -o main.o 
/home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp: In function ‘at::Tensor kda_inter_fused(at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor)’:
/home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp:48:28: error: ‘C’ was not declared in this scope; did you mean ‘c10::attr::C’?
   48 |     int shmem = (K_ * V_ + C * K_ + C * V_) * sizeof(float);
      |                            ^
      |                            c10::attr::C
In file included from

... (4530 more chars)
assistant
in 127out 125cache_r 153600cache_w 0
assistant
write /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (322 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -1,7 +1,7 @@
 """KDA forward (chunk form) — custom CUDA C++ kernel via load_inline.
 
-Hybrid: CUDA for intra-chunk correction + fused inter-chunk recurrence.
-PyTorch for: reshape, elementwise, initial matmuls (k_plus@k_minus^T).
+CUDA kernels: intra-chunk correction + fused inter-chunk recurrence.
+PyTorch: reshape, elementwise, initial matmuls.
 """
 from __future__ import annotations
 
@@ -51,25 +51,28 @@
     }
 }
 
+extern "C" void launch_intra_correction(
+    float* A, int stride_A,
+    const float* beta, int stride_beta,
+    int total_chunks
+) {
+    int shmem = C * C * sizeof(float);
+    intra_correction_kernel<<<total_chunks, C, shmem>>>(
+        A, stride_A, beta, stride_beta, total_chunks
+    );
+}
+
 // ===========================================================================
 // Fused inter-chunk recurrence.
 //
 // Grid: (B, H)   Block: C threads (one per intra-chunk row)
-//
-// Shared memory layout:
-//   S[K,V]    (64KB)
-//   km[C,K]   (32KB) -- k_minus for the current chunk
-//   vbar[C,V] (32KB) -- v_bar for the current chunk
-// TOTAL: 128KB
+// Shared: S[K,V](64KB) + km[C,K](32KB) + vbar[C,V](32KB) = 128KB
 //
 // Per chunk:
-//   1. Load km from global -> shared
-//   2. All C threads compute vbar_i = u_i - w_i @ S  (parallel)
-//   3. Store vbar to shared
-//   4. All C threads compute o_i in parallel:
-//      o_i[v] = qp_i @ S[:,v] + sum_{j<i} (qp_i @ km_j) * vbar_j[v]
-//   5. Write o_i to global
-//   6. All C threads update S = decay * (S + km^T @ vbar)  (parallel)
+//   1. Load km to shared; compute vbar_i = u_i - w_i @ S
+//   2. Store vbar to shared; compute o_i = qp_i @ S + sum_{j<i} (qp_i@km_j)*vbar_j
+//   3. Write o_i
+//   4. S = decay * (S + km^T @ vbar)
 // ===========================================================================
 __global__ void inter_fused_kernel(
     const float* __restrict__ qp, const float* __restrict__ km,
@@ -92,7 +95,6 @@
     int st_n_c_k = C * K_;
     int st_n_c_v = C * V_;
 
-    // Initialise S to 0
     for (int i = tid; i < K_ * V_; i += C) S[i] = 0.0f;
     __syncthreads();
 
@@ -107,77 +109,54 @@
         const float* g_n  = g  + cn * st_n_c_k;
         float* o_n        = o  + cn * st_n_c_v;
 
-        // ---- Step 1: Load km into shared ----
+        // Load km to shared
         for (int k = 0; k < K_; k++)
             km_sh[tid * K_ + k] = km_n[tid * st_c_k + k];
         __syncthreads();
 
-        // ---- Decay vector ----
+        // Decay vector
         float decay[128];
         for (int k = tid; k < K_; k += C)
             decay[k] = expf(g_n[(C - 1) * st_c_k + k]);
-        __syncthreads();
-
-        // ---- Step 2: Compute vbar_i = u_i - w_i @ S ----
-        // Load w_i, u_i
+
+        // Load w_i, u_i, compute vbar_i = u_i - w_i @ S
         float w_i[128], u_i[128];
-        #pragma unroll
         for (int k = 0; k < K_; k++) w_i[k] = w_n[tid * st_c_k + k];
-        #pragma unroll
         for (int v = 0; v < V_; v++) u_i[v] = u_n[tid * st_c_v + v];
 
-        // vbar_i[v] = u_i[v] - sum_k w_i[k] * S[k][v]
         float vbar_i[128];
-        #pragma unroll
         for (int v = 0; v < V_; v++) {
             float s = 0.0f;
-            #pragma unroll
-            for (int k = 0; k < K_; k++)
-                s += w_i[k] * S[k * V_ + v];
+            for (int k = 0; k < K_; k++) s += w_i[k] * S[k * V_ + v];
             vbar_i[v] = u_i[v] - s;
         }
 
-        // ---- Step 3: Store vbar to shared ----
-        #pragma unroll
-        for (int v = 0; v < V_; v++)
-            vb_sh[tid * V_ + v] = vbar_i[v];
-        __syncthreads();
-
-        // ---- Step 4: Compute o_i = qp_i @ S + sum_j (qp_i @ km_j) * vbar_j ----
+        for (int v = 0; v < V_; v++) vb_sh[tid * V_ + v] = vbar_i[v];
+        __syncthreads();
+
+        // Compute o_i = qp_i @ S + sum_j (qp_i @ km_j) * vbar_j
         float qp_i[128];
-        #pragma unroll
         for (int k = 0; k < K_; k++) qp_i[k] = qp_n[tid * st_c_k + k];
 
         float o_i[128];
         // qp_i @ S
-        #pragma unroll
         for (int v = 0; v < V_; v++) {
             float s = 0.0f;
-            #pragma unroll
-            for (int k = 0; k < K_; k++)
-                s += qp_i[k] * S[k * V_ + v];
+            for (int k = 0; k < K_; k++) s += qp_i[k] * S[k * V_ + v];
             o_i[v] = s;
         }
-        // Aqk @ vbar: qp_i @ sum_{j<tid} km_j * vbar_j
+        // Aqk @ vbar: sum_{j<tid} (qp_i @ km_j) * vbar_j
         for (int j = 0; j < tid; j++) {
-            float aqk_ij = 0.0f;
-            for (int k = 0; k < K_; k++)
-                aqk_ij += qp_i[k] * km_sh[j * K_ + k];
-            for (int v = 0; v < V_; v++)
-                o_i[v] += aqk_ij * vb_sh[j * V_ + v];
-        }
-        __syncthreads();  // ensure vbar not needed by other threads' o_i
-
-        // ---- Step 5: Write o_i ----
-        #pragma unroll
-        for (int v = 0; v < V_; v++)
-            o_n[tid * st_c_v + v] = o_i[v];
-
-        // ---- Step 6: Update S = decay * (S + km^T @ vbar) ----
-        // Each thread tid handles rows tid, tid+C, tid+2C, ... of S (K rows)
-        // For each k-row: compute sum_{j} km_sh[j][k] * vbar_j[v]
-        // km_sh[j][k] = km_sh[j * K_ + k]
-        // vb_sh[j][v] = vb_sh[j * V_ + v]
+            float aqk = 0.0f;
+            for (int k = 0; k < K_; k++) aqk += qp_i[k] * km_sh[j * K_ + k];
+            for (int v = 0; v < V_; v++) o_i[v] += aqk * vb_sh[j * V_ + v];
+        }
+        __syncthreads();
+
+        // Write o
+        for (int v = 0; v < V_; v++) o_n[tid * st_c_v + v] = o_i[v];
+
+        // S = decay * (S + km^T @ vbar)
         for (int kk = tid; kk < K_; kk += C) {
             for (int v = 0; v < V_; v++) {
                 float s = 0.0f;
@@ -189,6 +168,19 @@
         __syncthreads();
     }
 }
+
+extern "C" void laun

... (5515 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "content": "<11649 chars \u2014 see diff>"
}
tool
stdout (24 chars)
Wrote file successfully.
assistant
Issues: `C` not defined in C++ source, and kernel launch syntax belongs in CUDA source, not C++. Let me restructure.
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bash
args
{
  "command": "<130 chars \u2014 see below>",
  "description": "Test CUDA compilation",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (130 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution
print('CUDA:', solution._cuda_module is not None)
" 2>&1 | tail -5
tool
stdout (841 chars)
[2/3] /usr/local/cuda-13/bin/nvcc -MD -MF cuda.cuda.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -D__CUDA_NO_HALF_OPERATORS__ -D__CUDA_NO_HALF_CONVERSIONS__ -D__CUDA_NO_BFLOAT16_CONVERSIONS__ -D__CUDA_NO_HALF2_OPERATORS__ --expt-relaxed-constexpr -gencode=arch=compute_120,code=compute_120 -gencode=arch=compute_120,code=sm_120 --compiler-options '-fPIC' -O3 --use_fast_math -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/cuda.cu -o cuda.cuda.o 
ninja: build stopped: subcommand failed.

[WARN] Falling back to pure PyTorch
CUDA: False
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bash
args
{
  "description": "Get full compilation error",
  "command": "<70 chars \u2014 see below>",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (70 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution
" 2>&1
tool
stdout (2404 chars) — TRUNCATED
[WARN] CUDA compilation failed: Error building extension 'kda_cutlass_cu': [1/2] c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -fPIC -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp -o main.o 
FAILED: main.o 
c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=kda_cutlass_cu -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/include -isystem /usr/local/cuda-13/include -isystem /usr/include/python3.12 -fPIC -std=c++17 -c /home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp -o main.o 
/home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp: In function ‘at::Tensor kda_inter_fused(at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor)’:
/home/infatoshi/.cache/torch_extensions/py312_cu130/kda_cutlass_cu/main.cpp:52:13: error: invalid conversion from ‘void (*)(const float*, const float*, const float*, const float*, const float*, float*, int, int, int, int, int, int)’ to ‘const void*’ [-fpermissive]
   52 |             launch_inter_fused,
      |             ^~~~~

... (904 more chars)
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edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (16 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -176,6 +176,13 @@
     int B_, int H_, int NT, int K_, int V_,
     int shmem_size
 ) {
+    if (shmem_size > 48 * 1024) {
+        cudaFuncSetAttribute(
+            inter_fused_kernel,
+            cudaFuncAttributeMaxDynamicSharedMemorySize,
+            shmem_size
+        );
+    }
     dim3 grid(B_, H_);
     inter_fused_kernel<<<grid, C, shmem_size>>>(
         qp, km, w, u, g, o, B_, H_, NT, K_, V_
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<334 chars \u2014 see below>",
  "newString": "<527 chars \u2014 see below>"
}
oldString (334 chars)
extern "C" void launch_inter_fused(
    const float* qp, const float* km,
    const float* w, const float* u, const float* g,
    float* o,
    int B_, int H_, int NT, int K_, int V_,
    int shmem_size
) {
    dim3 grid(B_, H_);
    inter_fused_kernel<<<grid, C, shmem_size>>>(
        qp, km, w, u, g, o, B_, H_, NT, K_, V_
    );
}
newString (527 chars)
extern "C" void launch_inter_fused(
    const float* qp, const float* km,
    const float* w, const float* u, const float* g,
    float* o,
    int B_, int H_, int NT, int K_, int V_,
    int shmem_size
) {
    if (shmem_size > 48 * 1024) {
        cudaFuncSetAttribute(
            inter_fused_kernel,
            cudaFuncAttributeMaxDynamicSharedMemorySize,
            shmem_size
        );
    }
    dim3 grid(B_, H_);
    inter_fused_kernel<<<grid, C, shmem_size>>>(
        qp, km, w, u, g, o, B_, H_, NT, K_, V_
    );
}
tool
stdout (26 chars)
Edit applied successfully.
assistant
in 765out 388cache_r 160896cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (16 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -241,13 +241,6 @@
     auto o_c = o.contiguous();
 
     int shmem = (K_ * V_ + C * K_ + C * V_) * sizeof(float);
-    if (shmem > 48 * 1024) {
-        cudaFuncSetAttribute(
-            launch_inter_fused,
-            cudaFuncAttributeMaxDynamicSharedMemorySize,
-            shmem
-        );
-    }
 
     launch_inter_fused(
         qp_c.data_ptr<float>(), km_c.data_ptr<float>(),
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<268 chars \u2014 see below>",
  "newString": "<85 chars \u2014 see below>"
}
oldString (268 chars)
    int shmem = (K_ * V_ + C * K_ + C * V_) * sizeof(float);
    if (shmem > 48 * 1024) {
        cudaFuncSetAttribute(
            launch_inter_fused,
            cudaFuncAttributeMaxDynamicSharedMemorySize,
            shmem
        );
    }

    launch_inter_fused(
newString (85 chars)
    int shmem = (K_ * V_ + C * K_ + C * V_) * sizeof(float);

    launch_inter_fused(
tool
stdout (26 chars)
Edit applied successfully.
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assistant
bash
args
{
  "command": "<139 chars \u2014 see below>",
  "description": "Test CUDA compilation",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (139 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution
print('CUDA compiled:', solution._cuda_module is not None)
" 2>&1 | tail -3
tool
stdout (20 chars)
CUDA compiled: True
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assistant
bash
args
{
  "command": "python check.py 2>&1",
  "description": "Run correctness check with fused inter kernel",
  "timeout": 180000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
tool
stdout (1602 chars) — TRUNCATED
Traceback (most recent call last):
  File "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/check.py", line 113, in <module>
    main()
  File "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/check.py", line 74, in main
    sol_out = sol_model(*inputs)
              ^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1779, in _wrapped_call_impl
    return self._call_impl(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1790, in _call_impl
    return forward_call(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py", line 351, in forward
    return _kda_chunk_forward(q, k, v, g, beta, scale=self.scale, chunk_size=self.chunk_size)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py", line 339, in _kda_chunk_forward
    return o.to(dtype)
           ^^^^^^^^^^^
torch.AcceleratorError: CUDA error: invalid argument
Search for `cudaErrorInvalidValue' in https://docs.nvidia.com/cuda/cuda-runtime-api/group__CUDART__TYPES.html for more information.
CUDA kernel errors might be asynchronously reported at some other API call, so the stacktrace below might be incorrect.
For debugging conside

... (102 more chars)
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bash
args
{
  "description": "Debug with CUDA_LAUNCH_BLOCKING",
  "command": "<833 chars \u2014 see below>",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (833 chars)
CUDA_LAUNCH_BLOCKING=1 python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'
for k, v in {'B':1,'T':128,'H':1,'K':16,'V':16,'CHUNK_SIZE':64}.items():
    setattr(reference, k, v)

init_args = reference.get_init_inputs()
ref_model = reference.Model(*init_args).to(device).eval()
sol_model = solution.Model(*init_args).to(device).eval()
sol_model.load_state_dict(ref_model.state_dict(), strict=True)

torch.manual_seed(42)
torch.cuda.manual_seed_all(42)
inputs = [t.to(device) if hasattr(t,'to') else t for t in reference.get_inputs()]

with torch.no_grad():
    ref_out = ref_model(*inputs)
    sol_out = sol_model(*inputs)

diff = (ref_out.float() - sol_out.float()).abs()
print('PASS' if diff.max().item() < 0.05 else 'FAIL', f'max_diff={diff.max().item():.6f}')
" 2>&1 | tail -5
tool
stdout (23 chars)
PASS max_diff=0.004028
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bash
args
{
  "command": "<962 chars \u2014 see below>",
  "description": "Test large shape with CUDA_LAUNCH_BLOCKING",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (962 chars)
CUDA_LAUNCH_BLOCKING=1 python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'

for shape_name, shape in [
    ('B2_T1024_H8', {'B':2,'T':1024,'H':8,'K':128,'V':128,'CHUNK_SIZE':64}),
]:
    for k,v in shape.items():
        setattr(reference, k, v)

    init_args = reference.get_init_inputs()
    ref_model = reference.Model(*init_args).to(device).eval()
    sol_model = solution.Model(*init_args).to(device).eval()
    sol_model.load_state_dict(ref_model.state_dict(), strict=True)

    torch.manual_seed(42)
    torch.cuda.manual_seed_all(42)
    inputs = [t.to(device) if hasattr(t,'to') else t for t in reference.get_inputs()]
    with torch.no_grad():
        ref_out = ref_model(*inputs)
        sol_out = sol_model(*inputs)
    diff = (ref_out.float() - sol_out.float()).abs()
    print(f'{shape_name}: max_diff={diff.max().item():.6f}', 'PASS' if diff.max().item() < 0.05 else 'FAIL')
" 2>&1 | tail -5
tool
stdout (266 chars)
^^^^^^^^^^^
torch.AcceleratorError: CUDA error: invalid argument
Search for `cudaErrorInvalidValue' in https://docs.nvidia.com/cuda/cuda-runtime-api/group__CUDART__TYPES.html for more information.
Compile with `TORCH_USE_CUDA_DSA` to enable device-side assertions.

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The cudaFuncSetAttribute call is failing on SM120. Let me debug and fix.
assistant
bash
args
{
  "command": "<1282 chars \u2014 see below>",
  "description": "Test cudaFuncSetAttribute on SM120",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1282 chars)
python -c "
import torch
from torch.utils.cpp_extension import load_inline

# Test cudaFuncSetAttribute directly
code = '''
#include <cuda_runtime.h>
#include <cuda.h>

__global__ void test_kernel() {
    extern __shared__ float s[];
    s[threadIdx.x] = threadIdx.x;
}

extern \"C\" void test_launch(int size) {
    cudaError_t err = cudaFuncSetAttribute(
        test_kernel,
        cudaFuncAttributeMaxDynamicSharedMemorySize,
        size
    );
    if (err != cudaSuccess) {
        printf(\"cudaFuncSetAttribute error: %s\\n\", cudaGetErrorString(err));
    }
    dim3 grid(1), block(32);
    test_kernel<<<grid, block, size>>>();
    err = cudaGetLastError();
    if (err != cudaSuccess) {
        printf(\"Kernel launch error: %s\\n\", cudaGetErrorString(err));
    }
    cudaDeviceSynchronize();
    printf(\"Done\\n\");
}
'''

cpp = '''
#include <torch/extension.h>
extern \"C\" void test_launch(int size);
void test_fn(int size) { test_launch(size); }
PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def(\"test_fn\", &test_fn);
}
'''

mod = load_inline('test_shmem', cpp_sources=cpp, cuda_sources=code, functions=['test_fn'], verbose=False)
# Test with 128KB
mod.test_fn(128 * 1024)
print('128KB OK')
# Test with 200KB
mod.test_fn(200 * 1024)  
print('200KB OK')
" 2>&1
tool
stdout (9455 chars) — TRUNCATED
Traceback (most recent call last):
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2774, in _run_ninja_build
    subprocess.run(
  File "/usr/lib/python3.12/subprocess.py", line 571, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['ninja', '-v']' returned non-zero exit status 1.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<string>", line 44, in <module>
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2174, in load_inline
    return _jit_compile(
           ^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2268, in _jit_compile
    _write_ninja_file_and_build_library(
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2429, in _write_ninja_file_and_build_library
    _run_ninja_build(
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2791, in _run_ninja_build
    raise RuntimeError(message) from e
RuntimeError: Error building extension 'test_shmem': [1/3] /usr/local/cuda-13/bin/nvcc -MD -MF cuda.cuda.o.d -DTORCH_EXTENSION_NAME=test_shmem -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include

... (7955 more chars)
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edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (236 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -63,16 +63,23 @@
 }
 
 // ===========================================================================
-// Fused inter-chunk recurrence.
+// Fused inter-chunk recurrence — low shared-memory variant.
 //
-// Grid: (B, H)   Block: C threads (one per intra-chunk row)
-// Shared: S[K,V](64KB) + km[C,K](32KB) + vbar[C,V](32KB) = 128KB
+// Grid: (B, H)   Block: C threads
+// Shared: S[K,V] only (64KB). km and vbar NOT stored in shared memory.
 //
-// Per chunk:
-//   1. Load km to shared; compute vbar_i = u_i - w_i @ S
-//   2. Store vbar to shared; compute o_i = qp_i @ S + sum_{j<i} (qp_i@km_j)*vbar_j
-//   3. Write o_i
-//   4. S = decay * (S + km^T @ vbar)
+// For each chunk n, process rows SEQUENTIALLY (one thread active at a time):
+//   Thread i:
+//     1. Load qp_i, km_i, w_i, u_i from global
+//     2. vbar = u_i - w_i @ S
+//     3. o_i = qp_i @ S + sum_{j<i} (qp_i @ km_j) * vbar_j
+//        where km_j and vbar_j were saved to global in previous iterations
+//     4. Write km_i, vbar_i to global temp buffers
+//     5. Write o_i to global
+//   After all rows: S update using the saved km/vbar
+//
+// This uses 1 thread at a time (C* slower in compute), but eliminates the
+// shared memory issue and the inter-thread synchronization.
 // ===========================================================================
 __global__ void inter_fused_kernel(
     const float* __restrict__ qp, const float* __restrict__ km,
@@ -83,20 +90,54 @@
 ) {
     int b = blockIdx.x, h = blockIdx.y;
     if (b >= B_ || h >= H_) return;
-    int tid = threadIdx.x;  // row index 0..C-1
 
     extern __shared__ float shm[];
-    float* S     = shm;                              // [K, V]
-    float* km_sh = shm + K_ * V_;                    // [C, K]
-    float* vb_sh = shm + K_ * V_ + C * K_;           // [C, V]
+    float* S = shm;  // [K, V]
+
+    // Temp global buffers: km_buf[C,K], vb_buf[C,V] — per (B,H)
+    // We need persistent temp memory. Use thread-local storage + temp output.
+    // Actually, let's use a different approach:
+    // Process chunks with a register-only running_accum.
+    //
+    // Alternative: allocate a temp buffer in global memory.
+    // km_buf: (B, H, C, K) and vb_buf: (B, H, C, V)
+    // These are per-(B,H) temp buffers, allocated externally.
+    
+    // For now, use a simplified approach: keep km and vbar in temp global buffers
+    // passed as extra arguments.
+}
+
+// ===========================================================================
+// Revised inter-chunk kernel — keeps S in shared mem, uses global temp for km/vbar.
+// ===========================================================================
+__global__ void inter_fused_kernel_v2(
+    const float* __restrict__ qp, const float* __restrict__ km,
+    const float* __restrict__ w,  const float* __restrict__ u,
+    const float* __restrict__ g,
+    float* __restrict__ o,
+    float* __restrict__ km_buf,   // [B, H, C, K] temp
+    float* __restrict__ vb_buf,   // [B, H, C, V] temp
+    int B_, int H_, int NT, int K_, int V_
+) {
+    int b = blockIdx.x, h = blockIdx.y;
+    if (b >= B_ || h >= H_) return;
+    int tid = threadIdx.x;
+
+    extern __shared__ float S[];
+    // S has K_ * V_ elements
 
     int st_c_k = K_;
     int st_c_v = V_;
-    int st_n_c_k = C * K_;
-    int st_n_c_v = C * V_;
+    int st_bh_c_k = C * K_;
+    int st_bh_c_v = C * V_;
+    int st_bh = C * K_ + C * V_;  // stride for bg and bh in temp
 
     for (int i = tid; i < K_ * V_; i += C) S[i] = 0.0f;
     __syncthreads();
+
+    // Temp buffer offsets for this (B,H)
+    float* kmb = km_buf + (b * H_ + h) * C * K_;
+    float* vbb = vb_buf + (b * H_ + h) * C * V_;
 
     int base = (b * H_ + h) * NT;
 
@@ -109,64 +150,98 @@
         const float* g_n  = g  + cn * st_n_c_k;
         float* o_n        = o  + cn * st_n_c_v;
 
-        // Load km to shared
-        for (int k = 0; k < K_; k++)
-            km_sh[tid * K_ + k] = km_n[tid * st_c_k + k];
-        __syncthreads();
-
         // Decay vector
         float decay[128];
         for (int k = tid; k < K_; k += C)
             decay[k] = expf(g_n[(C - 1) * st_c_k + k]);
 
-        // Load w_i, u_i, compute vbar_i = u_i - w_i @ S
-        float w_i[128], u_i[128];
-        for (int k = 0; k < K_; k++) w_i[k] = w_n[tid * st_c_k + k];
-        for (int v = 0; v < V_; v++) u_i[v] = u_n[tid * st_c_v + v];
-
-        float vbar_i[128];
-        for (int v = 0; v < V_; v++) {
-            float s = 0.0f;
-            for (int k = 0; k < K_; k++) s += w_i[k] * S[k * V_ + v];
-            vbar_i[v] = u_i[v] - s;
+        // Process rows sequentially
+        for (int i = 0; i < C; i++) {
+            if (tid == i) {
+                // This thread handles row i
+                float qp_i[128], km_i[128], w_i[128], u_i[128];
+                for (int k = 0; k < K_; k++) {
+                    qp_i[k] = qp_n[i * st_c_k + k];
+                    km_i[k] = km_n[i * st_c_k + k];
+                    w_i[k]  = w_n[i * st_c_k + k];
+                }
+                for (int v = 0; v < V_; v++)
+                    u_i[v] = u_n[i * st_c_v + v];
+
+                // vbar
+                float vbar_i[128];
+                for (int v = 0; v < V_; v++) {
+                    float s = 0.0f;
+                    for (int k = 0; k < K_; k++)
+                        s += w_i[k] * S[k * V_ + v];
+                    vbar_i[v] = u_i[v] - s;
+                }
+
+                // o_i = qp_i @ S
+                // Since we don't have other threads' vbar in shared, recompute
+                // the Aqk term from the km_buf and vb_buf (previous rows)
+                float o_i[128];
+                for (int v = 0; v < V_; v++) {
+                    float s = 0.0f;
+                    for (int k = 0; k < K_; k++)
+                  

... (3080 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<3732 chars \u2014 see below>",
  "newString": "<6777 chars \u2014 see below>"
}
oldString (3732 chars)
// ===========================================================================
// Fused inter-chunk recurrence.
//
// Grid: (B, H)   Block: C threads (one per intra-chunk row)
// Shared: S[K,V](64KB) + km[C,K](32KB) + vbar[C,V](32KB) = 128KB
//
// Per chunk:
//   1. Load km to shared; compute vbar_i = u_i - w_i @ S
//   2. Store vbar to shared; compute o_i = qp_i @ S + sum_{j<i} (qp_i@km_j)*vbar_j
//   3. Write o_i
//   4. S = decay * (S + km^T @ vbar)
// ===========================================================================
__global__ void inter_fused_kernel(
    const float* __restrict__ qp, const float* __restrict__ km,
    const float* __restrict__ w,  const float* __restrict__ u,
    const float* __restrict__ g,
    float* __restrict__ o,
    int B_, int H_, int NT, int K_, int V_
) {
    int b = blockIdx.x, h = blockIdx.y;
    if (b >= B_ || h >= H_) return;
    int tid = threadIdx.x;  // row index 0..C-1

    extern __shared__ float shm[];
    float* S     = shm;                              // [K, V]
    float* km_sh = shm + K_ * V_;                    // [C, K]
    float* vb_sh = shm + K_ * V_ + C * K_;           // [C, V]

    int st_c_k = K_;
    int st_c_v = V_;
    int st_n_c_k = C * K_;
    int st_n_c_v = C * V_;

    for (int i = tid; i < K_ * V_; i += C) S[i] = 0.0f;
    __syncthreads();

    int base = (b * H_ + h) * NT;

    for (int n = 0; n < NT; n++) {
        int cn = base + n;
        const float* qp_n = qp + cn * st_n_c_k;
        const float* km_n = km + cn * st_n_c_k;
        const float* w_n  = w  + cn * st_n_c_k;
        const float* u_n  = u  + cn * st_n_c_v;
        const float* g_n  = g  + cn * st_n_c_k;
        float* o_n        = o  + cn * st_n_c_v;

        // Load km to shared
        for (int k = 0; k < K_; k++)
            km_sh[tid * K_ + k] = km_n[tid * st_c_k + k];
        __syncthreads();

        // Decay vector
        float decay[128];
        for (int k = tid; k < K_; k += C)
            decay[k] = expf(g_n[(C - 1) * st_c_k + k]);

        // Load w_i, u_i, compute vbar_i = u_i - w_i @ S
        float w_i[128], u_i[128];
        for (int k = 0; k < K_; k++) w_i[k] = w_n[tid * st_c_k + k];
        for (int v = 0; v < V_; v++) u_i[v] = u_n[tid * st_c_v + v];

        float vbar_i[128];
        for (int v = 0; v < V_; v++) {
            float s = 0.0f;
            for (int k = 0; k < K_; k++) s += w_i[k] * S[k * V_ + v];
            vbar_i[v] = u_i[v] - s;
        }

        for (int v = 0; v < V_; v++) vb_sh[tid * V_ + v] = vbar_i[v];
        __syncthreads();

        // Compute o_i = qp_i @ S + sum_j (qp_i @ km_j) * vbar_j
        float qp_i[128];
        for (int k = 0; k < K_; k++) qp_i[k] = qp_n[tid * st_c_k + k];

        float o_i[128];
        // qp_i @ S
        for (int v = 0; v < V_; v++) {
            float s = 0.0f;
            for (int k = 0; k < K_; k++) s += qp_i[k] * S[k * V_ + v];
            o_i[v] = s;
        }
        // Aqk @ vbar: sum_{j<tid} (qp_i @ km_j) * vbar_j
        for (int j = 0; j < tid; j++) {
            float aqk = 0.0f;
            for (int k = 0; k < K_; k++) aqk += qp_i[k] * km_sh[j * K_ + k];
            for (int v = 0; v < V_; v++) o_i[v] += aqk * vb_sh[j * V_ + v];
        }
        __syncthreads();

        // Write o
        for (int v = 0; v < V_; v++) o_n[tid * st_c_v + v] = o_i[v];

        // S = decay * (S + km^T @ vbar)
        for (int kk = tid; kk < K_; kk += C) {
            for (int v = 0; v < V_; v++) {
                float s = 0.0f;
                for (int j = 0; j < C; j++)
                    s += km_sh[j * K_ + kk] * vb_sh[j * V_ + v];
                S[kk * V_ + v] = decay[kk] * (S[kk * V_ + v] + s);
            }
        }
        __syncthreads();
    }
}
newString (6777 chars — TRUNCATED)
// ===========================================================================
// Fused inter-chunk recurrence — low shared-memory variant.
//
// Grid: (B, H)   Block: C threads
// Shared: S[K,V] only (64KB). km and vbar NOT stored in shared memory.
//
// For each chunk n, process rows SEQUENTIALLY (one thread active at a time):
//   Thread i:
//     1. Load qp_i, km_i, w_i, u_i from global
//     2. vbar = u_i - w_i @ S
//     3. o_i = qp_i @ S + sum_{j<i} (qp_i @ km_j) * vbar_j
//        where km_j and vbar_j were saved to global in previous iterations
//     4. Write km_i, vbar_i to global temp buffers
//     5. Write o_i to global
//   After all rows: S update using the saved km/vbar
//
// This uses 1 thread at a time (C* slower in compute), but eliminates the
// shared memory issue and the inter-thread synchronization.
// ===========================================================================
__global__ void inter_fused_kernel(
    const float* __restrict__ qp, const float* __restrict__ km,
    const float* __restrict__ w,  const float* __restrict__ u,
    const float* __restrict__ g,
    float* __restrict__ o,
    int B_, int H_, int NT, int K_, int V_
) {
    int b = blockIdx.x, h = blockIdx.y;
    if (b >= B_ || h >= H_) return;

    extern __shared__ float shm[];
    float* S = shm;  // [K, V]

    // Temp global buffers: km_buf[C,K], vb_buf[C,V] — per (B,H)
    // We need persistent temp memory. Use thread-local storage + temp output.
    // Actually, let's use a different approach:
    // Process chunks with a register-only running_accum.
    //
    // Alternative: allocate a temp buffer in global memory.
    // km_buf: (B, H, C, K) and vb_buf: (B, H, C, V)
    // These are per-(B,H) temp buffers, allocated externally.
    
    // For now, use a simplified approach: keep km and vbar in temp global buffers
    // passed as extra arguments.
}

// ===========================================================================
// Revised inter-chunk kernel — keeps S in shared mem, uses global temp for km/vbar.
// ===========================================================================
__global__ void inter_fused_kernel_v2(
    const float* __restrict__ qp, const float* __restrict__ km,
    const float* __restrict__ w,  const float* __restrict__ u,
    const float* __restrict__ g,
    float* __restrict__ o,
    float* __restrict__ km_buf,   // [B, H, C, K] temp
    float* __restrict__ vb_buf,   // [B, H, C, V] temp
    int B_, int H_, int NT, int K_, int V_
) {
    int b = blockIdx.x, h = blockIdx.y;
    if (b >= B_ || h >= H_) return;
    int tid = threadIdx.x;

    extern __shared__ float S[];
    // S has K_ * V_ elements

    int st_c_k = K_;
    int st_c_v = V_;
    int st_bh_c_k = C * K_;
    int st_bh_c_v = C * V_;
    int st_bh = C * K_ + C * V_;  // stride for bg and bh in temp

    for (int i = tid; i < K_ * V_; i += C) S[i] = 0.0f;
    __syncthreads();

    // Temp buffer offsets for this (B,H)
    float* kmb = km_buf + (b * H_ + h) * C * K_;
    float* vbb = vb_buf + (b * H_ + h) * C * V_;

    int base = (b * H_ + h) * NT;

    for (int n = 0; n < NT; n++) {
        int cn = base + n;
        const float* qp_n = qp + cn * st_n_c_k;
        const float* km_n = km + cn * st_n_c_k;
        const float* w_n  = w  + cn * st_n_c_k;
        const float* u_n  = u  + cn * st_n_c_v;
        const float* g_n  = g  + cn * st_n_c_k;
        float* o_n        = o  + cn * st_n_c_v;

        // Decay vector
        float decay[128];
        for (int k = tid; k < K_; k += C)
            decay[k] = expf(g_n[(C - 1) * st_c_k + k]);

        // Process rows sequentially
        for (int i = 0; i < C; i++) {
            if (tid == i) {
                // This thread handles row i
                float qp_i[128], km_i[128], w_i[128], u_i[128];
                for (int k = 0; k < K_; k++) {
                    qp_i[k] = qp_n[i * st_c_k + k];
                    km_i[k] = km_n[i * st_c_k + k];
                    w_i[k]  = w_n[i

... (2777 more chars)
tool
stdout (26 chars)
Edit applied successfully.
assistant
Let me try a simpler approach: use less shared memory by moving vbar to registers instead of shared memory in the fused inter kernel.
assistant
in 3102out 3593cache_r 167680cache_w 0
assistant
Let me take a cleaner approach — a single kernel per chunk that replaces the 4 bmm calls.
assistant
bash
args
{
  "command": "<148 chars \u2014 see below>",
  "description": "Check shared memory limits",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (148 chars)
python -c "
# Test: what's the max shared mem on SM120?
import torch
print(torch.cuda.get_device_properties(0).max_shared_memory_per_block_opt_in)
"
tool
stdout (232 chars)
Traceback (most recent call last):
  File "<string>", line 4, in <module>
AttributeError: 'torch._C._CudaDeviceProperties' object has no attribute 'max_shared_memory_per_block_opt_in'. Did you mean: 'shared_memory_per_block_optin'?
assistant
in 141out 162cache_r 174592cache_w 0
assistant
bash
args
{
  "command": "<282 chars \u2014 see below>",
  "description": "Check shared memory limits",
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (282 chars)
python -c "
import torch
p = torch.cuda.get_device_properties(0)
print('SM:', p.major, p.minor)
print('shared_mem_per_block:', p.shared_memory_per_block)
print('shared_mem_per_block_optin:', p.shared_memory_per_block_optin)
print('max_threads_per_block:', p.max_threads_per_block)
"
tool
stdout (100 chars)
SM: 12 0
shared_mem_per_block: 49152
shared_mem_per_block_optin: 101376
max_threads_per_block: 1024
assistant
in 3271out 181cache_r 174720cache_w 0
assistant
The opt-in shared mem max is 99KB. Let me test if `cudaFuncSetAttribute` works with a proper test:
assistant
bash
args
{
  "command": "<1597 chars \u2014 see below>",
  "description": "Test cudaFuncSetAttribute with proper error handling",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1597 chars)
python -c "
from torch.utils.cpp_extension import load_inline

code = r'''
#include <cuda_runtime.h>
#include <stdio.h>

__global__ void test_kernel(float* out) {
    extern __shared__ float s[];
    s[threadIdx.x] = threadIdx.x;
    out[threadIdx.x] = s[threadIdx.x];
}

extern \"C\" void test_launch(float* out, int shmem_bytes) {
    cudaError_t e;
    e = cudaFuncSetAttribute(
        test_kernel,
        cudaFuncAttributeMaxDynamicSharedMemorySize,
        shmem_bytes
    );
    const char* err_str = cudaGetErrorString(e);
    // Copy error string to pinned memory or just print
    printf(\"cudaFuncSetAttribute(%d): %s\\n\", shmem_bytes, err_str);
    
    test_kernel<<<1, 32, shmem_bytes>>>(out);
    e = cudaGetLastError();
    printf(\"Launch: %s\\n\", cudaGetErrorString(e));
    cudaDeviceSynchronize();
    printf(\"Sync: %s\\n\", cudaGetErrorString(cudaGetLastError()));
}
'''

cpp = '''
#include <torch/extension.h>
extern \"C\" void test_launch(float* out, int shmem_bytes);
void test_fn(torch::Tensor out, int shmem_bytes) {
    test_launch(out.data_ptr<float>(), shmem_bytes);
}
PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def(\"test_fn\", &test_fn);
}
'''

mod = load_inline('test_shmem2', cpp_sources=cpp, cuda_sources=code, functions=['test_fn'], verbose=False)
x = torch.zeros(32, device='cuda')
for size in [48*1024, 64*1024, 99*1024, 128*1024]:
    try:
        mod.test_fn(x, size)
        print(f'Size {size//1024}KB: OK')
    except Exception as e:
        print(f'Size {size//1024}KB: FAILED - {e}')
" 2>&1 | grep -E "^(Size|cudaFuncSetAttribute|Launch|Sync)"
tool
stdout (11 chars)
(no output)
assistant
in 176out 651cache_r 178048cache_w 0
assistant
bash
args
{
  "command": "<1366 chars \u2014 see below>",
  "description": "Test shared memory with stderr",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1366 chars)
python -c "
from torch.utils.cpp_extension import load_inline

code = '''
#include <cuda_runtime.h>
#include <stdio.h>

__global__ void test_kernel() {
    extern __shared__ float s[];
    s[threadIdx.x] = 1.0f;
}

extern \"C\" void test_launch(int shmem_bytes) {
    cudaError_t e;
    e = cudaFuncSetAttribute(
        test_kernel,
        cudaFuncAttributeMaxDynamicSharedMemorySize,
        shmem_bytes
    );
    if (e != cudaSuccess) {
        fprintf(stderr, \"FAIL shmem=%d: %s\\n\", shmem_bytes, cudaGetErrorString(e));
        return;
    }
    test_kernel<<<1, 32, shmem_bytes>>>();
    e = cudaGetLastError();
    if (e != cudaSuccess) {
        fprintf(stderr, \"FAIL launch shmem=%d: %s\\n\", shmem_bytes, cudaGetErrorString(e));
        return;
    }
    cudaDeviceSynchronize();
    fprintf(stderr, \"OK shmem=%d\\n\", shmem_bytes);
}
'''

cpp = '''
#include <torch/extension.h>
extern \"C\" void test_launch(int shmem_bytes);
void test_fn(int shmem_bytes) { test_launch(shmem_bytes); }
PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def(\"test_fn\", &test_fn);
}
'''

mod = load_inline('test_shmem3', cpp_sources=cpp, cuda_sources=code, functions=['test_fn'], verbose=False)
for size in [48*1024, 64*1024, 99*1024, 100*1024]:
    try:
        mod.test_fn(size)
    except Exception as e:
        print(f'Size {size//1024}KB: EXCEPTION {e}')
" 2>&1
tool
stdout (9544 chars) — TRUNCATED
Traceback (most recent call last):
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2774, in _run_ninja_build
    subprocess.run(
  File "/usr/lib/python3.12/subprocess.py", line 571, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['ninja', '-v']' returned non-zero exit status 1.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<string>", line 44, in <module>
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2174, in load_inline
    return _jit_compile(
           ^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2268, in _jit_compile
    _write_ninja_file_and_build_library(
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2429, in _write_ninja_file_and_build_library
    _run_ninja_build(
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2791, in _run_ninja_build
    raise RuntimeError(message) from e
RuntimeError: Error building extension 'test_shmem3': [1/3] /usr/local/cuda-13/bin/nvcc -MD -MF cuda.cuda.o.d -DTORCH_EXTENSION_NAME=test_shmem3 -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/inclu

... (8044 more chars)
assistant
in 37out 549cache_r 181760cache_w 0
assistant
write /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (496 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -1,7 +1,7 @@
 """KDA forward (chunk form) — custom CUDA C++ kernel via load_inline.
 
-CUDA kernels: intra-chunk correction + fused inter-chunk recurrence.
-PyTorch: reshape, elementwise, initial matmuls.
+Hybrid: CUDA intra-chunk correction + CUDA per-chunk inter kernel.
+PyTorch: reshape, elementwise exp/mul, initial matmuls (A = k_plus@k_minus^T).
 """
 from __future__ import annotations
 
@@ -16,7 +16,7 @@
 #define C 64
 
 // ===========================================================================
-// Intra-chunk triangular correction
+// Intra-chunk triangular correction (grid=total_chunks, block=C, shmem=C*C*4B)
 // ===========================================================================
 __global__ void intra_correction_kernel(
     float* __restrict__ A, int stride_A,
@@ -51,6 +51,122 @@
     }
 }
 
+// ===========================================================================
+// Per-chunk inter kernel — replaces the PyTorch per-chunk bmm calls.
+// Grid: (B, H)  Block: C threads  Shared: S[K,V] (64KB for K=V=128)
+//
+// This kernel handles ONE chunk. Called NT times in sequence.
+// S is shared memory, km_buf/vb_buf are global temp (per (B,H)).
+// ===========================================================================
+__global__ void inter_chunk_kernel(
+    const float* __restrict__ qp,    // (B,H,NT,C,K)
+    const float* __restrict__ km,    // (B,H,NT,C,K)
+    const float* __restrict__ w,     // (B,H,NT,C,K)
+    const float* __restrict__ u,     // (B,H,NT,C,V)
+    const float* __restrict__ g,     // (B,H,NT,C,K)
+    float* __restrict__ o,           // (B,H,NT,C,V)
+    float* __restrict__ km_buf,      // (B,H,C,K) — temp, carries between calls
+    float* __restrict__ vb_buf,      // (B,H,C,V) — temp
+    float* __restrict__ S_global,    // (B,H,K,V) — state, in/out
+    int B_, int H_, int NT, int K_, int V_,
+    int chunk_n                      // which chunk (0..NT-1)
+) {
+    int b = blockIdx.x, h = blockIdx.y;
+    if (b >= B_ || h >= H_) return;
+    int tid = threadIdx.x;
+
+    extern __shared__ float S[];  // [K, V]
+
+    int st_c_k = K_;
+    int st_c_v = V_;
+    int st_n_c_k = C * K_;
+    int st_n_c_v = C * V_;
+
+    // Load S from global -> shared (or use existing)
+    // On first call (chunk_n==0), S_global is zeros. Load into shared.
+    int S_offset = (b * H_ + h) * K_ * V_;
+    for (int i = tid; i < K_ * V_; i += C)
+        S[i] = S_global[S_offset + i];
+    __syncthreads();
+
+    int cn = (b * H_ + h) * NT + chunk_n;
+    const float* qp_n = qp + cn * st_n_c_k;
+    const float* km_n = km + cn * st_n_c_k;
+    const float* w_n  = w  + cn * st_n_c_k;
+    const float* u_n  = u  + cn * st_n_c_v;
+    const float* g_n  = g  + cn * st_n_c_k;
+    float* o_n        = o  + cn * st_n_c_v;
+
+    // Temp offsets for this (B,H)
+    float* kmb = km_buf + (b * H_ + h) * C * K_;
+    float* vbb = vb_buf + (b * H_ + h) * C * V_;
+
+    // ---- Decay ----
+    float decay[128];
+    for (int k = tid; k < K_; k += C)
+        decay[k] = expf(g_n[(C - 1) * st_c_k + k]);
+
+    // ---- Step 1: Load km_i to global temp ----
+    for (int k = 0; k < K_; k++)
+        kmb[tid * K_ + k] = km_n[tid * st_c_k + k];
+
+    // ---- Step 2: Compute vbar_i = u_i - w_i @ S ----
+    float w_i[128], u_i[128];
+    for (int k = 0; k < K_; k++) w_i[k] = w_n[tid * st_c_k + k];
+    for (int v = 0; v < V_; v++) u_i[v] = u_n[tid * st_c_v + v];
+
+    float vbar_i[128];
+    for (int v = 0; v < V_; v++) {
+        float s = 0.0f;
+        for (int k = 0; k < K_; k++) s += w_i[k] * S[k * V_ + v];
+        vbar_i[v] = u_i[v] - s;
+    }
+
+    // ---- Write vbar_i to global temp ----
+    for (int v = 0; v < V_; v++) vbb[tid * V_ + v] = vbar_i[v];
+
+    __syncthreads();  // ensure kmb and vbb are visible to all threads in block
+
+    // ---- Step 3: Compute o_i = qp_i @ S + sum_j (qp_i @ km_j) * vbar_j ----
+    float qp_i[128];
+    for (int k = 0; k < K_; k++) qp_i[k] = qp_n[tid * st_c_k + k];
+
+    float o_i[128];
+    // qp_i @ S
+    for (int v = 0; v < V_; v++) {
+        float s = 0.0f;
+        for (int k = 0; k < K_; k++) s += qp_i[k] * S[k * V_ + v];
+        o_i[v] = s;
+    }
+    // Aqk @ vbar: sum_{j<tid} (qp_i @ km_j) * vbar_j
+    // kmb and vbb are in L1-cached global memory (written by same block)
+    for (int j = 0; j < tid; j++) {
+        float aqk = 0.0f;
+        for (int k = 0; k < K_; k++) aqk += qp_i[k] * kmb[j * K_ + k];
+        for (int v = 0; v < V_; v++) o_i[v] += aqk * vbb[j * V_ + v];
+    }
+
+    // ---- Write o_i ----
+    for (int v = 0; v < V_; v++) o_n[tid * st_c_v + v] = o_i[v];
+    __syncthreads();
+
+    // ---- Step 4: S = decay * (S + km^T @ vbar) ----
+    // kmb and vbb have all rows written by this block
+    for (int kk = tid; kk < K_; kk += C) {
+        for (int v = 0; v < V_; v++) {
+            float s = 0.0f;
+            for (int j = 0; j < C; j++)
+                s += kmb[j * K_ + kk] * vbb[j * V_ + v];
+            S[kk * V_ + v] = decay[kk] * (S[kk * V_ + v] + s);
+        }
+    }
+    __syncthreads();
+
+    // ---- Store S back to global ----
+    for (int i = tid; i < K_ * V_; i += C)
+        S_global[S_offset + i] = S[i];
+}
+
 extern "C" void launch_intra_correction(
     float* A, int stride_A,
     const float* beta, int stride_beta,
@@ -61,214 +177,12 @@
         A, stride_A, beta, stride_beta, total_chunks
     );
 }
-
-// ===========================================================================
-// Fused inter-chunk recurrence — low shared-memory variant.
-//
-// Grid: (B, H)   Block: C threads
-// Shared: S[K,V] only (64KB). km and vbar NOT stored in shared memory.
-//
-// For each chunk n, process rows SEQUENTIALLY (one thread active at a time):
-//   Thread i:
-//     1. Load qp_i, km_i, w_i, u_i from global
-//     2. vbar = 

... (11964 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "content": "<11132 chars \u2014 see diff>"
}
tool
stdout (24 chars)
Wrote file successfully.
assistant
Let me skip the shmem test and directly update the solution with the correct approach. The opt-in shared mem is 99KB, which can fit S (64KB). Let me use a clean kernel per chunk with S in shared memory.
assistant
in 3118out 4098cache_r 182400cache_w 0
assistant
Let me go back to the working solution and try torch.compile optimization, since it's simpler than fighting with shared memory limits.
assistant
bash
args
{
  "command": "<1262 chars \u2014 see below>",
  "description": "Benchmark current solution",
  "timeout": 120000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1262 chars)
python -c "
import sys, os
sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath('.')), '..'))
import shapes, solution
import torch

device = 'cuda:0'
torch.set_float32_matmul_precision('high')

for shape_idx, shape in enumerate(shapes.SHAPES):
    B,T,H,K,V = shape['B'], shape['T'], shape['H'], shape['K'], shape['V']
    model = solution.Model(B, T, H, K, V, 64).to(device).eval()
    
    torch.manual_seed(2026)
    q = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
    k = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
    v = torch.randn(B, T, H, V, dtype=torch.bfloat16, device=device) * 0.1
    g = torch.randn(B, T, H, K, dtype=torch.float32, device=device) * 0.1 - 0.05
    beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16, device=device))
    inputs = [q, k, v, g, beta]
    
    # Warmup
    for _ in range(3):
        model(*inputs)
    
    torch.cuda.synchronize()
    start = torch.cuda.Event(enable_timing=True)
    end = torch.cuda.Event(enable_timing=True)
    start.record()
    for _ in range(20):
        model(*inputs)
    end.record()
    torch.cuda.synchronize()
    ms = start.elapsed_time(end) / 20
    print(f'shape={shape_idx} B={B} T={T} H={H}: {ms:.3f} ms')
" 2>&1
tool
stdout (132 chars)
shape=0 B=2 T=1024 H=8: 1.330 ms
shape=1 B=2 T=2048 H=8: 2.513 ms
shape=2 B=1 T=4096 H=8: 4.853 ms
shape=3 B=1 T=2048 H=4: 2.524 ms
assistant
in 67out 581cache_r 190848cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (67 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -281,27 +281,47 @@
     q_plus = torch.exp(g) * q
     o = torch.zeros_like(v)
 
+    # --- Pre-compute all Aqk in one batched call ---
+    # Aqk_all = q_plus @ k_minus^T  (B, H, NT, C, C), strict lower
+    Aqk_all = torch.matmul(q_plus, k_minus.transpose(-2, -1))
+    mask2 = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk_all.device), diagonal=1)
+    Aqk_all = Aqk_all.masked_fill(mask2, 0.0)
+
+    # Pre-compute km * exp(g_last) for S update
+    # g[:,:,:,-1:,:] is the last g entry in each chunk
+    g_last_all = g[:, :, :, -1:, :]  # (B, H, NT, 1, K)
+    km_decayed = k_minus * g_last_all.exp()  # (B, H, NT, C, K)
+
+    # Also pre-compute decay per chunk
+    decay_all = g_last_all.exp().squeeze(-2).unsqueeze(-1)  # (B, H, NT, K, 1)
+
     # --- Inter-chunk ---
     S = torch.zeros(B, H, K_, V, dtype=torch.float32, device=q.device)
+    qp_flat = q_plus.reshape(B * H, NT, BT, K_)
+    km_flat = k_minus.reshape(B * H, NT, BT, K_)
+    w_flat = w.reshape(B * H, NT, BT, K_)
+    u_flat = u.reshape(B * H, NT, BT, V)
+    o_flat = o.reshape(B * H, NT, BT, V)
+    decay_flat = decay_all.reshape(B * H, NT, K_, 1)
+    km_dec_flat = km_decayed.reshape(B * H, NT, BT, K_)
+    Aqk_flat = Aqk_all.reshape(B * H, NT, BT, BT)
 
     for n in range(NT):
-        qp_n, km_n, w_n, u_n, g_n = [x[:, :, n] for x in (q_plus, k_minus, w, u, g)]
-
-        # Aqk = q_plus @ k_minus^T  (B, H, C, C), strict lower
-        Aqk = torch.matmul(qp_n, km_n.transpose(-2, -1))
-        mask2 = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk.device), diagonal=1)
-        Aqk = Aqk.masked_fill(mask2, 0.0)
-
-        # v_bar = u - w @ S
-        v_bar = u_n - torch.matmul(w_n, S)
-
-        # o = q_plus @ S + Aqk @ v_bar
-        o[:, :, n] = torch.matmul(qp_n, S) + torch.matmul(Aqk, v_bar)
-
-        # S update: decay * (S + (k_minus^T @ v_bar))
-        g_last = g_n[:, :, -1:, :]
-        decay = g_last.exp().squeeze(-2).unsqueeze(-1)  # (B, H, K, 1)
-        S = S * decay + torch.matmul((km_n * g_last.exp()).transpose(-2, -1), v_bar)
+        qp_n = qp_flat[:, n]     # (B*H, C, K)
+        km_n = km_flat[:, n]     # (B*H, C, K)
+        w_n = w_flat[:, n]       # (B*H, C, K)
+        u_n = u_flat[:, n]       # (B*H, C, V)
+        Aqk_n = Aqk_flat[:, n]   # (B*H, C, C)
+        decay_n = decay_flat[:, n]  # (B*H, K, 1)
+
+        v_bar = u_n - torch.bmm(w_n, S.reshape(B * H, K_, V))
+        qS = torch.bmm(qp_n, S.reshape(B * H, K_, V))
+        o_flat[:, n] = qS + torch.bmm(Aqk_n, v_bar)
+
+        # S update
+        S = S.reshape(B * H, K_, V)
+        S = S * decay_n + torch.bmm(km_dec_flat[:, n].transpose(-2, -1), v_bar)
+        S = S.reshape(B, H, K_, V)
 
     o = rearrange(o, "b h n c d -> b (n c) h d")
     return o.to(dtype)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<966 chars \u2014 see below>",
  "newString": "<1868 chars \u2014 see below>"
}
oldString (966 chars)
    # --- Inter-chunk ---
    S = torch.zeros(B, H, K_, V, dtype=torch.float32, device=q.device)

    for n in range(NT):
        qp_n, km_n, w_n, u_n, g_n = [x[:, :, n] for x in (q_plus, k_minus, w, u, g)]

        # Aqk = q_plus @ k_minus^T  (B, H, C, C), strict lower
        Aqk = torch.matmul(qp_n, km_n.transpose(-2, -1))
        mask2 = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk.device), diagonal=1)
        Aqk = Aqk.masked_fill(mask2, 0.0)

        # v_bar = u - w @ S
        v_bar = u_n - torch.matmul(w_n, S)

        # o = q_plus @ S + Aqk @ v_bar
        o[:, :, n] = torch.matmul(qp_n, S) + torch.matmul(Aqk, v_bar)

        # S update: decay * (S + (k_minus^T @ v_bar))
        g_last = g_n[:, :, -1:, :]
        decay = g_last.exp().squeeze(-2).unsqueeze(-1)  # (B, H, K, 1)
        S = S * decay + torch.matmul((km_n * g_last.exp()).transpose(-2, -1), v_bar)

    o = rearrange(o, "b h n c d -> b (n c) h d")
    return o.to(dtype)
newString (1868 chars)
    # --- Pre-compute all Aqk in one batched call ---
    # Aqk_all = q_plus @ k_minus^T  (B, H, NT, C, C), strict lower
    Aqk_all = torch.matmul(q_plus, k_minus.transpose(-2, -1))
    mask2 = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk_all.device), diagonal=1)
    Aqk_all = Aqk_all.masked_fill(mask2, 0.0)

    # Pre-compute km * exp(g_last) for S update
    # g[:,:,:,-1:,:] is the last g entry in each chunk
    g_last_all = g[:, :, :, -1:, :]  # (B, H, NT, 1, K)
    km_decayed = k_minus * g_last_all.exp()  # (B, H, NT, C, K)

    # Also pre-compute decay per chunk
    decay_all = g_last_all.exp().squeeze(-2).unsqueeze(-1)  # (B, H, NT, K, 1)

    # --- Inter-chunk ---
    S = torch.zeros(B, H, K_, V, dtype=torch.float32, device=q.device)
    qp_flat = q_plus.reshape(B * H, NT, BT, K_)
    km_flat = k_minus.reshape(B * H, NT, BT, K_)
    w_flat = w.reshape(B * H, NT, BT, K_)
    u_flat = u.reshape(B * H, NT, BT, V)
    o_flat = o.reshape(B * H, NT, BT, V)
    decay_flat = decay_all.reshape(B * H, NT, K_, 1)
    km_dec_flat = km_decayed.reshape(B * H, NT, BT, K_)
    Aqk_flat = Aqk_all.reshape(B * H, NT, BT, BT)

    for n in range(NT):
        qp_n = qp_flat[:, n]     # (B*H, C, K)
        km_n = km_flat[:, n]     # (B*H, C, K)
        w_n = w_flat[:, n]       # (B*H, C, K)
        u_n = u_flat[:, n]       # (B*H, C, V)
        Aqk_n = Aqk_flat[:, n]   # (B*H, C, C)
        decay_n = decay_flat[:, n]  # (B*H, K, 1)

        v_bar = u_n - torch.bmm(w_n, S.reshape(B * H, K_, V))
        qS = torch.bmm(qp_n, S.reshape(B * H, K_, V))
        o_flat[:, n] = qS + torch.bmm(Aqk_n, v_bar)

        # S update
        S = S.reshape(B * H, K_, V)
        S = S * decay_n + torch.bmm(km_dec_flat[:, n].transpose(-2, -1), v_bar)
        S = S.reshape(B, H, K_, V)

    o = rearrange(o, "b h n c d -> b (n c) h d")
    return o.to(dtype)
tool
stdout (26 chars)
Edit applied successfully.
assistant
Let me try a practical optimization path. First, pre-compute Aqk and other shared ops in batch, then benchmark again.
assistant
in 143out 1267cache_r 192384cache_w 0
assistant
bash
args
{
  "command": "<1008 chars \u2014 see below>",
  "description": "Test optimized solution",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1008 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'

# Quick correctness test
init_args = solution.get_init_inputs()
ref_model = reference.Model(*init_args).to(device).eval()
sol_model = solution.Model(*init_args).to(device).eval()
sd = ref_model.state_dict()
sol_model.load_state_dict(sd, strict=True)

torch.manual_seed(42)
torch.cuda.manual_seed_all(42)
inputs = [t.to(device) if hasattr(t,'to') else t for t in reference.get_inputs()]

with torch.no_grad():
    ref_out = ref_model(*inputs)
    sol_out = sol_model(*inputs)

diff = (ref_out.float() - sol_out.float()).abs()
print('PASS' if diff.max().item() < 0.05 else 'FAIL', f'max_diff={diff.max().item():.6f}')

# Benchmark
torch.cuda.synchronize()
start = torch.cuda.Event(enable_timing=True)
end = torch.cuda.Event(enable_timing=True)
start.record()
for _ in range(20):
    sol_model(*inputs)
end.record()
torch.cuda.synchronize()
ms = start.elapsed_time(end) / 20
print(f'ms={ms:.3f}')
" 2>&1
tool
stdout (32 chars)
PASS max_diff=0.011719
ms=0.824
assistant
in 42out 419cache_r 194432cache_w 0
assistant
bash
args
{
  "command": "<1730 chars \u2014 see below>",
  "description": "Test cudaFuncSetAttribute properly",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1730 chars)
python -c "
from torch.utils.cpp_extension import load_inline

code = r'''
#include <cuda_runtime.h>
#include <stdio.h>

__global__ void test_kernel(float* out, int K, int V) {
    extern __shared__ float S[];
    int tid = threadIdx.x;
    for (int i = tid; i < K * V; i += blockDim.x)
        S[i] = (float)i;
    __syncthreads();
    if (tid == 0) {
        float sum = 0;
        for (int i = 0; i < K * V; i++) sum += S[i];
        out[0] = sum;
    }
}

extern \"C\" void test_launch(float* out, int K, int V, int shmem_bytes) {
    cudaError_t e = cudaFuncSetAttribute(
        test_kernel,
        cudaFuncAttributeMaxDynamicSharedMemorySize,
        shmem_bytes
    );
    if (e != cudaSuccess) {
        fprintf(stderr, \"FAIL setAttr(%d): %s\\n\", shmem_bytes, cudaGetErrorString(e));
        return;
    }
    test_kernel<<<1, 64, shmem_bytes>>>(out, K, V);
    e = cudaGetLastError();
    if (e != cudaSuccess) {
        fprintf(stderr, \"FAIL launch(%d): %s\\n\", shmem_bytes, cudaGetErrorString(e));
        return;
    }
    cudaDeviceSynchronize();
    fprintf(stderr, \"OK(%d)\\n\", shmem_bytes);
}
'''

cpp = '''
#include <torch/extension.h>
extern \"C\" void test_launch(float* out, int K, int V, int shmem_bytes);
void test_fn(torch::Tensor out, int K, int V, int shmem_bytes) {
    test_launch(out.data_ptr<float>(), K, V, shmem_bytes);
}
PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def(\"test_fn\", &test_fn);
}
'''

mod = load_inline('test_shmem_final', cpp_sources=cpp, cuda_sources=code, functions=['test_fn'], verbose=False)
out = torch.zeros(1, device='cuda')
for size in [48*1024, 64*1024, 96*1024]:
    print(f'Trying {size//1024}KB...')
    mod.test_fn(out, 128, 128, size)
print('Done')
" 2>&1
tool
stdout (5117 chars) — TRUNCATED
Traceback (most recent call last):
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2774, in _run_ninja_build
    subprocess.run(
  File "/usr/lib/python3.12/subprocess.py", line 571, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['ninja', '-v']' returned non-zero exit status 1.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<string>", line 53, in <module>
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2174, in load_inline
    return _jit_compile(
           ^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2268, in _jit_compile
    _write_ninja_file_and_build_library(
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2429, in _write_ninja_file_and_build_library
    _run_ninja_build(
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2791, in _run_ninja_build
    raise RuntimeError(message) from e
RuntimeError: Error building extension 'test_shmem_final': [1/3] c++ -MMD -MF main.o.d -DTORCH_EXTENSION_NAME=test_shmem_final -DTORCH_API_INCLUDE_EXTENSION_H -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include -isystem /home/infatoshi/.local/lib/python3.12/site-packages/torch/include/torch/csrc/api/

... (3617 more chars)
assistant
in 47out 685cache_r 194944cache_w 0
assistant
bash
args
{
  "command": "<1652 chars \u2014 see below>",
  "description": "Test shared memory with proper PYBIND11",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1652 chars)
python -c "
from torch.utils.cpp_extension import load_inline

code = r'''
#include <cuda_runtime.h>
#include <stdio.h>

__global__ void test_kernel(float* out, int K, int V) {
    extern __shared__ float S[];
    int tid = threadIdx.x;
    for (int i = tid; i < K * V; i += blockDim.x) S[i] = (float)i;
    __syncthreads();
    if (tid == 0) {
        float sum = 0;
        for (int i = 0; i < K * V; i++) sum += S[i];
        out[0] = sum;
    }
}

extern \"C\" void test_launch(float* out, int K, int V, int shmem_bytes) {
    cudaError_t e = cudaFuncSetAttribute(
        test_kernel,
        cudaFuncAttributeMaxDynamicSharedMemorySize,
        shmem_bytes
    );
    if (e != cudaSuccess) {
        fprintf(stderr, \"FAIL setAttr(%d): %s\n\", shmem_bytes, cudaGetErrorString(e));
        return;
    }
    test_kernel<<<1, 64, shmem_bytes>>>(out, K, V);
    e = cudaGetLastError();
    if (e != cudaSuccess) {
        fprintf(stderr, \"FAIL launch(%d): %s\n\", shmem_bytes, cudaGetErrorString(e));
        return;
    }
    cudaDeviceSynchronize();
    fprintf(stderr, \"OK(%d)\n\", shmem_bytes);
}
'''

cpp = '''
#include <torch/extension.h>
extern \"C\" void test_launch(float* out, int K, int V, int shmem_bytes);
void test_fn(torch::Tensor out, int K, int V, int shmem_bytes) {
    test_launch(out.data_ptr<float>(), K, V, shmem_bytes);
}
PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def(\"test_fn\", &test_fn);
}
'''

mod = load_inline('test_shmem5', cpp_sources=cpp, cuda_sources=code, verbose=False)
out = torch.zeros(1, device='cuda')
for size in [48*1024, 64*1024, 96*1024]:
    mod.test_fn(out, 128, 128, size)
print('Done')
" 2>&1
tool
stdout (114 chars)
Traceback (most recent call last):
  File "<string>", line 53, in <module>
NameError: name 'torch' is not defined
assistant
in 1743out 664cache_r 195712cache_w 0
assistant
bash
args
{
  "command": "<1694 chars \u2014 see below>",
  "description": "Test shared memory with heredoc",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1694 chars)
python << 'PYEOF'
import torch
from torch.utils.cpp_extension import load_inline

code = r'''
#include <cuda_runtime.h>
#include <stdio.h>

__global__ void test_kernel(float* out, int K, int V) {
    extern __shared__ float S[];
    int tid = threadIdx.x;
    for (int i = tid; i < K * V; i += blockDim.x) S[i] = (float)i;
    __syncthreads();
    if (tid == 0) {
        float sum = 0;
        for (int i = 0; i < K * V; i++) sum += S[i];
        out[0] = sum;
    }
}

extern "C" void test_launch(float* out, int K, int V, int shmem_bytes) {
    cudaError_t e = cudaFuncSetAttribute(
        test_kernel,
        cudaFuncAttributeMaxDynamicSharedMemorySize,
        shmem_bytes
    );
    if (e != cudaSuccess) {
        fprintf(stderr, "FAIL setAttr(%d): %s\n", shmem_bytes, cudaGetErrorString(e));
        return;
    }
    test_kernel<<<1, 64, shmem_bytes>>>(out, K, V);
    e = cudaGetLastError();
    if (e != cudaSuccess) {
        fprintf(stderr, "FAIL launch(%d): %s\n", shmem_bytes, cudaGetErrorString(e));
        return;
    }
    cudaDeviceSynchronize();
    fprintf(stderr, "OK(%d)\n", shmem_bytes);
}
'''

cpp = '''
#include <torch/extension.h>
extern "C" void test_launch(float* out, int K, int V, int shmem_bytes);
void test_fn(torch::Tensor out, int K, int V, int shmem_bytes) {
    test_launch(out.data_ptr<float>(), K, V, shmem_bytes);
}
PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def("test_fn", &test_fn);
}
'''

mod = load_inline('test_shmem5', cpp_sources=cpp, cuda_sources=code, verbose=False)
out = torch.zeros(1, device='cuda')
for size in [48*1024, 64*1024, 96*1024]:
    mod.test_fn(out, 128, 128, size)
    print(f'  size={size//1024}KB')
print('Done')
PYEOF
tool
stdout (175 chars)
OK(49152)
FAIL setAttr(65536): an illegal memory access was encountered
FAIL setAttr(98304): an illegal memory access was encountered
  size=48KB
  size=64KB
  size=96KB
Done
assistant
in 147out 676cache_r 198400cache_w 0
assistant
write /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (338 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -1,7 +1,7 @@
 """KDA forward (chunk form) — custom CUDA C++ kernel via load_inline.
 
-Hybrid: CUDA intra-chunk correction + CUDA per-chunk inter kernel.
-PyTorch: reshape, elementwise exp/mul, initial matmuls (A = k_plus@k_minus^T).
+CUDA: intra-chunk correction + per-chunk inter kernel (no shared mem).
+PyTorch: reshape, elementwise exp/mul, initial matmuls.
 """
 from __future__ import annotations
 
@@ -16,7 +16,7 @@
 #define C 64
 
 // ===========================================================================
-// Intra-chunk triangular correction (grid=total_chunks, block=C, shmem=C*C*4B)
+// Intra-chunk triangular correction
 // ===========================================================================
 __global__ void intra_correction_kernel(
     float* __restrict__ A, int stride_A,
@@ -52,44 +52,38 @@
 }
 
 // ===========================================================================
-// Per-chunk inter kernel — replaces the PyTorch per-chunk bmm calls.
-// Grid: (B, H)  Block: C threads  Shared: S[K,V] (64KB for K=V=128)
+// Per-chunk inter kernel — zero shared memory, uses global (L1-cached) for S.
 //
-// This kernel handles ONE chunk. Called NT times in sequence.
-// S is shared memory, km_buf/vb_buf are global temp (per (B,H)).
+// Grid: (B, H)  Block: C threads  Shared: 0 bytes
+//
+// S is stored in global memory (B, H, K, V). Fits in 192KB L1 cache.
+// km_buf and vb_buf are global temp per (B,H) — also L1 cached (32KB each).
+//
+// Called NT times sequentially, once per chunk.
 // ===========================================================================
 __global__ void inter_chunk_kernel(
-    const float* __restrict__ qp,    // (B,H,NT,C,K)
-    const float* __restrict__ km,    // (B,H,NT,C,K)
-    const float* __restrict__ w,     // (B,H,NT,C,K)
-    const float* __restrict__ u,     // (B,H,NT,C,V)
-    const float* __restrict__ g,     // (B,H,NT,C,K)
-    float* __restrict__ o,           // (B,H,NT,C,V)
-    float* __restrict__ km_buf,      // (B,H,C,K) — temp, carries between calls
-    float* __restrict__ vb_buf,      // (B,H,C,V) — temp
-    float* __restrict__ S_global,    // (B,H,K,V) — state, in/out
+    const float* __restrict__ qp, const float* __restrict__ km,
+    const float* __restrict__ w,  const float* __restrict__ u,
+    const float* __restrict__ g,
+    float* __restrict__ o,
+    float* __restrict__ km_buf,   // (B, H, C, K) temp
+    float* __restrict__ vb_buf,   // (B, H, C, V) temp
+    float* __restrict__ S_global, // (B, H, K, V) state
     int B_, int H_, int NT, int K_, int V_,
-    int chunk_n                      // which chunk (0..NT-1)
+    int chunk_n
 ) {
     int b = blockIdx.x, h = blockIdx.y;
     if (b >= B_ || h >= H_) return;
-    int tid = threadIdx.x;
-
-    extern __shared__ float S[];  // [K, V]
+    int tid = threadIdx.x;  // row index 0..C-1
 
     int st_c_k = K_;
     int st_c_v = V_;
     int st_n_c_k = C * K_;
     int st_n_c_v = C * V_;
 
-    // Load S from global -> shared (or use existing)
-    // On first call (chunk_n==0), S_global is zeros. Load into shared.
-    int S_offset = (b * H_ + h) * K_ * V_;
-    for (int i = tid; i < K_ * V_; i += C)
-        S[i] = S_global[S_offset + i];
-    __syncthreads();
-
-    int cn = (b * H_ + h) * NT + chunk_n;
+    int bh = b * H_ + h;
+    int cn = bh * NT + chunk_n;
+
     const float* qp_n = qp + cn * st_n_c_k;
     const float* km_n = km + cn * st_n_c_k;
     const float* w_n  = w  + cn * st_n_c_k;
@@ -97,20 +91,19 @@
     const float* g_n  = g  + cn * st_n_c_k;
     float* o_n        = o  + cn * st_n_c_v;
 
-    // Temp offsets for this (B,H)
-    float* kmb = km_buf + (b * H_ + h) * C * K_;
-    float* vbb = vb_buf + (b * H_ + h) * C * V_;
+    // Temp buffer pointers for this (B,H)
+    float* kmb = km_buf + bh * C * K_;
+    float* vbb = vb_buf + bh * C * V_;
+    float* S = S_global + bh * K_ * V_;
 
     // ---- Decay ----
     float decay[128];
-    for (int k = tid; k < K_; k += C)
-        decay[k] = expf(g_n[(C - 1) * st_c_k + k]);
-
-    // ---- Step 1: Load km_i to global temp ----
-    for (int k = 0; k < K_; k++)
-        kmb[tid * K_ + k] = km_n[tid * st_c_k + k];
-
-    // ---- Step 2: Compute vbar_i = u_i - w_i @ S ----
+    for (int k = tid; k < K_; k += C) decay[k] = expf(g_n[(C - 1) * st_c_k + k]);
+
+    // ---- Step 1: Write km_i to global temp ----
+    for (int k = 0; k < K_; k++) kmb[tid * K_ + k] = km_n[tid * st_c_k + k];
+
+    // ---- Step 2: vbar_i = u_i - w_i @ S ----
     float w_i[128], u_i[128];
     for (int k = 0; k < K_; k++) w_i[k] = w_n[tid * st_c_k + k];
     for (int v = 0; v < V_; v++) u_i[v] = u_n[tid * st_c_v + v];
@@ -122,12 +115,12 @@
         vbar_i[v] = u_i[v] - s;
     }
 
-    // ---- Write vbar_i to global temp ----
+    // Write vbar to global temp
     for (int v = 0; v < V_; v++) vbb[tid * V_ + v] = vbar_i[v];
 
-    __syncthreads();  // ensure kmb and vbb are visible to all threads in block
-
-    // ---- Step 3: Compute o_i = qp_i @ S + sum_j (qp_i @ km_j) * vbar_j ----
+    __syncthreads();
+
+    // ---- Step 3: o_i = qp_i @ S + sum_{j<tid} (qp_i @ km_j) * vbar_j ----
     float qp_i[128];
     for (int k = 0; k < K_; k++) qp_i[k] = qp_n[tid * st_c_k + k];
 
@@ -139,19 +132,17 @@
         o_i[v] = s;
     }
     // Aqk @ vbar: sum_{j<tid} (qp_i @ km_j) * vbar_j
-    // kmb and vbb are in L1-cached global memory (written by same block)
     for (int j = 0; j < tid; j++) {
         float aqk = 0.0f;
         for (int k = 0; k < K_; k++) aqk += qp_i[k] * kmb[j * K_ + k];
         for (int v = 0; v < V_; v++) o_i[v] += aqk * vbb[j * V_ + v];
     }
 
-    // ---- Write o_i ----
+    // Write o_i
     for (int v = 0; v < V_; v++) o_n[tid * st_c_v + v] = o_i[v];
     __syncthreads();
 
     // ---- Step 4: S = decay * (S + km^T @ vbar) ----
-    // kmb an

... (6567 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "content": "<11634 chars \u2014 see diff>"
}
tool
stdout (24 chars)
Wrote file successfully.
assistant
Found it! `cudaFuncSetAttribute` returns "illegal memory access" on SM120. Let me avoid shared memory entirely — use global memory with L1 caching for S (64KB fits in 192KB L1).
assistant
in 188out 4218cache_r 199296cache_w 0
assistant
bash
args
{
  "command": "<1040 chars \u2014 see below>",
  "description": "Test new fused per-chunk kernel",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1040 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'
print('CUDA module:', solution._cuda_module is not None)

init_args = solution.get_init_inputs()
ref_model = reference.Model(*init_args).to(device).eval()
sol_model = solution.Model(*init_args).to(device).eval()
sd = ref_model.state_dict()
sol_model.load_state_dict(sd, strict=True)

torch.manual_seed(42)
torch.cuda.manual_seed_all(42)
inputs = [t.to(device) if hasattr(t,'to') else t for t in reference.get_inputs()]

with torch.no_grad():
    ref_out = ref_model(*inputs)
    sol_out = sol_model(*inputs)

diff = (ref_out.float() - sol_out.float()).abs()
print('PASS' if diff.max().item() < 0.05 else 'FAIL', f'max_diff={diff.max().item():.6f}')

# Benchmark
torch.cuda.synchronize()
start = torch.cuda.Event(enable_timing=True)
end = torch.cuda.Event(enable_timing=True)
start.record()
for _ in range(20):
    sol_model(*inputs)
end.record()
torch.cuda.synchronize()
ms = start.elapsed_time(end) / 20
print(f'ms={ms:.3f}')
" 2>&1
tool
stdout (51 chars)
CUDA module: True
PASS max_diff=0.011719
ms=14.684
assistant
in 29out 433cache_r 207872cache_w 0
assistant
CUDA kernel is ~20x slower due to register spilling (640 registers > 255 limit per thread). Let me tile the V dimension to fix this.
assistant
bash
args
{
  "command": "<906 chars \u2014 see below>",
  "description": "Test PyTorch fallback",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (906 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'

# Test with PyTorch fallback only (CUDA module disabled for debugging)
# Compare against reference for correctness

init_args = solution.get_init_inputs()
ref_model = reference.Model(*init_args).to(device).eval()
# Force PyTorch path
solution._cuda_module.kda_inter_chunk = None
sol_model = solution.Model(*init_args).to(device).eval()
sol_model.load_state_dict(ref_model.state_dict(), strict=True)

torch.manual_seed(42)
torch.cuda.manual_seed_all(42)
inputs = [t.to(device) if hasattr(t,'to') else t for t in reference.get_inputs()]

with torch.no_grad():
    ref_out = ref_model(*inputs)
    sol_out = sol_model(*inputs)

diff = (ref_out.float() - sol_out.float()).abs()
print('PyTorch path max_diff:', diff.max().item())
print('PyTorch path PASS' if diff.max().item() < 0.05 else 'FAIL')
" 2>&1
tool
stdout (969 chars)
Traceback (most recent call last):
  File "<string>", line 24, in <module>
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1779, in _wrapped_call_impl
    return self._call_impl(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1790, in _call_impl
    return forward_call(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py", line 346, in forward
    return _kda_chunk_forward(q, k, v, g, beta, scale=self.scale, chunk_size=self.chunk_size)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py", line 314, in _kda_chunk_forward
    _cuda_module.kda_inter_chunk(
TypeError: 'NoneType' object is not callable
assistant
in 117out 404cache_r 208256cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (185 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -52,15 +52,18 @@
 }
 
 // ===========================================================================
-// Per-chunk inter kernel — zero shared memory, uses global (L1-cached) for S.
+// Per-chunk inter kernel — register-efficient, V-tiled.
 //
+// Uses V_TILE=32 to keep register pressure low.
 // Grid: (B, H)  Block: C threads  Shared: 0 bytes
 //
-// S is stored in global memory (B, H, K, V). Fits in 192KB L1 cache.
-// km_buf and vb_buf are global temp per (B,H) — also L1 cached (32KB each).
-//
-// Called NT times sequentially, once per chunk.
+// Key to register efficiency:
+//   - Process V in tiles of 32: only 32 floats in regs at a time
+//   - Process K in streaming fashion: 1 float at a time
+//   - max registers: vbar_tile(32) + o_tile(32) + aqk(1) + streams(~3) ≈ 70
 // ===========================================================================
+#define VT 32
+
 __global__ void inter_chunk_kernel(
     const float* __restrict__ qp, const float* __restrict__ km,
     const float* __restrict__ w,  const float* __restrict__ u,
@@ -74,12 +77,13 @@
 ) {
     int b = blockIdx.x, h = blockIdx.y;
     if (b >= B_ || h >= H_) return;
-    int tid = threadIdx.x;  // row index 0..C-1
+    int tid = threadIdx.x;
 
     int st_c_k = K_;
     int st_c_v = V_;
     int st_n_c_k = C * K_;
     int st_n_c_v = C * V_;
+    int nvt = (V_ + VT - 1) / VT;  // number of V-tiles
 
     int bh = b * H_ + h;
     int cn = bh * NT + chunk_n;
@@ -91,7 +95,6 @@
     const float* g_n  = g  + cn * st_n_c_k;
     float* o_n        = o  + cn * st_n_c_v;
 
-    // Temp buffer pointers for this (B,H)
     float* kmb = km_buf + bh * C * K_;
     float* vbb = vb_buf + bh * C * V_;
     float* S = S_global + bh * K_ * V_;
@@ -103,52 +106,98 @@
     // ---- Step 1: Write km_i to global temp ----
     for (int k = 0; k < K_; k++) kmb[tid * K_ + k] = km_n[tid * st_c_k + k];
 
-    // ---- Step 2: vbar_i = u_i - w_i @ S ----
-    float w_i[128], u_i[128];
-    for (int k = 0; k < K_; k++) w_i[k] = w_n[tid * st_c_k + k];
-    for (int v = 0; v < V_; v++) u_i[v] = u_n[tid * st_c_v + v];
-
-    float vbar_i[128];
-    for (int v = 0; v < V_; v++) {
-        float s = 0.0f;
-        for (int k = 0; k < K_; k++) s += w_i[k] * S[k * V_ + v];
-        vbar_i[v] = u_i[v] - s;
+    // ---- Step 2: vbar_i = u_i - w_i @ S, V-tiled ----
+    for (int vt = 0; vt < nvt; vt++) {
+        int v_off = vt * VT;
+        int v_end = min(V_, v_off + VT);
+
+        // Load u_i tile
+        float vbar[VT];
+        #pragma unroll
+        for (int tv = 0; tv < VT; tv++) {
+            int v = v_off + tv;
+            vbar[tv] = (v < v_end) ? u_n[tid * st_c_v + v] : 0.0f;
+        }
+
+        // Subtract w @ S tile
+        // Stream over K
+        for (int k = 0; k < K_; k++) {
+            float w_k = w_n[tid * st_c_k + k];
+            #pragma unroll
+            for (int tv = 0; tv < VT; tv++) {
+                int v = v_off + tv;
+                if (v < v_end) vbar[tv] -= w_k * S[k * V_ + v];
+            }
+        }
+
+        // Write vbar tile to global temp
+        #pragma unroll
+        for (int tv = 0; tv < VT; tv++) {
+            int v = v_off + tv;
+            if (v < v_end) vbb[tid * V_ + v] = vbar[tv];
+        }
     }
 
-    // Write vbar to global temp
-    for (int v = 0; v < V_; v++) vbb[tid * V_ + v] = vbar_i[v];
-
     __syncthreads();
 
     // ---- Step 3: o_i = qp_i @ S + sum_{j<tid} (qp_i @ km_j) * vbar_j ----
-    float qp_i[128];
-    for (int k = 0; k < K_; k++) qp_i[k] = qp_n[tid * st_c_k + k];
-
-    float o_i[128];
-    // qp_i @ S
-    for (int v = 0; v < V_; v++) {
-        float s = 0.0f;
-        for (int k = 0; k < K_; k++) s += qp_i[k] * S[k * V_ + v];
-        o_i[v] = s;
+    for (int vt = 0; vt < nvt; vt++) {
+        int v_off = vt * VT;
+        int v_end = min(V_, v_off + VT);
+
+        // qp_i @ S tile
+        float o_tile[VT];
+        #pragma unroll
+        for (int tv = 0; tv < VT; tv++) o_tile[tv] = 0.0f;
+
+        // Stream over K for qp_i @ S[tile]
+        for (int k = 0; k < K_; k++) {
+            float qp_k = qp_n[tid * st_c_k + k];
+            #pragma unroll
+            for (int tv = 0; tv < VT; tv++) {
+                int v = v_off + tv;
+                if (v < v_end) o_tile[tv] += qp_k * S[k * V_ + v];
+            }
+        }
+
+        // Aqk @ vbar tile: sum_{j<tid} (qp_i @ km_j) * vbar_j[v]
+        // For each j < tid: compute aqk_j (streaming over K), then scale vbar_j[tile]
+        for (int j = 0; j < tid; j++) {
+            float aqk = 0.0f;
+            for (int k = 0; k < K_; k++)
+                aqk += qp_n[tid * st_c_k + k] * kmb[j * K_ + k];
+            #pragma unroll
+            for (int tv = 0; tv < VT; tv++) {
+                int v = v_off + tv;
+                if (v < v_end) o_tile[tv] += aqk * vbb[j * V_ + v];
+            }
+        }
+
+        // Write o tile
+        #pragma unroll
+        for (int tv = 0; tv < VT; tv++) {
+            int v = v_off + tv;
+            if (v < v_end) o_n[tid * st_c_v + v] = o_tile[tv];
+        }
     }
-    // Aqk @ vbar: sum_{j<tid} (qp_i @ km_j) * vbar_j
-    for (int j = 0; j < tid; j++) {
-        float aqk = 0.0f;
-        for (int k = 0; k < K_; k++) aqk += qp_i[k] * kmb[j * K_ + k];
-        for (int v = 0; v < V_; v++) o_i[v] += aqk * vbb[j * V_ + v];
-    }
-
-    // Write o_i
-    for (int v = 0; v < V_; v++) o_n[tid * st_c_v + v] = o_i[v];
     __syncthreads();
 
     // ---- Step 4: S = decay * (S + km^T @ vbar) ----
-    for (int kk = tid; kk < K_; kk += C) {
-        for (int v = 0; v < V_; v++) {
-            float s = 0.0f;
-            for (int j = 0; j < C; j++)
-                s += kmb[j * K_ + kk] * vbb[j * V_ + v];
-            S[kk * V_ + v] = decay[kk] * (S[kk * V_ + v] + s);
+    // Each thread handles k rows: kk = 

... (601 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<3490 chars \u2014 see below>",
  "newString": "<5027 chars \u2014 see below>"
}
oldString (3490 chars)
// ===========================================================================
// Per-chunk inter kernel — zero shared memory, uses global (L1-cached) for S.
//
// Grid: (B, H)  Block: C threads  Shared: 0 bytes
//
// S is stored in global memory (B, H, K, V). Fits in 192KB L1 cache.
// km_buf and vb_buf are global temp per (B,H) — also L1 cached (32KB each).
//
// Called NT times sequentially, once per chunk.
// ===========================================================================
__global__ void inter_chunk_kernel(
    const float* __restrict__ qp, const float* __restrict__ km,
    const float* __restrict__ w,  const float* __restrict__ u,
    const float* __restrict__ g,
    float* __restrict__ o,
    float* __restrict__ km_buf,   // (B, H, C, K) temp
    float* __restrict__ vb_buf,   // (B, H, C, V) temp
    float* __restrict__ S_global, // (B, H, K, V) state
    int B_, int H_, int NT, int K_, int V_,
    int chunk_n
) {
    int b = blockIdx.x, h = blockIdx.y;
    if (b >= B_ || h >= H_) return;
    int tid = threadIdx.x;  // row index 0..C-1

    int st_c_k = K_;
    int st_c_v = V_;
    int st_n_c_k = C * K_;
    int st_n_c_v = C * V_;

    int bh = b * H_ + h;
    int cn = bh * NT + chunk_n;

    const float* qp_n = qp + cn * st_n_c_k;
    const float* km_n = km + cn * st_n_c_k;
    const float* w_n  = w  + cn * st_n_c_k;
    const float* u_n  = u  + cn * st_n_c_v;
    const float* g_n  = g  + cn * st_n_c_k;
    float* o_n        = o  + cn * st_n_c_v;

    // Temp buffer pointers for this (B,H)
    float* kmb = km_buf + bh * C * K_;
    float* vbb = vb_buf + bh * C * V_;
    float* S = S_global + bh * K_ * V_;

    // ---- Decay ----
    float decay[128];
    for (int k = tid; k < K_; k += C) decay[k] = expf(g_n[(C - 1) * st_c_k + k]);

    // ---- Step 1: Write km_i to global temp ----
    for (int k = 0; k < K_; k++) kmb[tid * K_ + k] = km_n[tid * st_c_k + k];

    // ---- Step 2: vbar_i = u_i - w_i @ S ----
    float w_i[128], u_i[128];
    for (int k = 0; k < K_; k++) w_i[k] = w_n[tid * st_c_k + k];
    for (int v = 0; v < V_; v++) u_i[v] = u_n[tid * st_c_v + v];

    float vbar_i[128];
    for (int v = 0; v < V_; v++) {
        float s = 0.0f;
        for (int k = 0; k < K_; k++) s += w_i[k] * S[k * V_ + v];
        vbar_i[v] = u_i[v] - s;
    }

    // Write vbar to global temp
    for (int v = 0; v < V_; v++) vbb[tid * V_ + v] = vbar_i[v];

    __syncthreads();

    // ---- Step 3: o_i = qp_i @ S + sum_{j<tid} (qp_i @ km_j) * vbar_j ----
    float qp_i[128];
    for (int k = 0; k < K_; k++) qp_i[k] = qp_n[tid * st_c_k + k];

    float o_i[128];
    // qp_i @ S
    for (int v = 0; v < V_; v++) {
        float s = 0.0f;
        for (int k = 0; k < K_; k++) s += qp_i[k] * S[k * V_ + v];
        o_i[v] = s;
    }
    // Aqk @ vbar: sum_{j<tid} (qp_i @ km_j) * vbar_j
    for (int j = 0; j < tid; j++) {
        float aqk = 0.0f;
        for (int k = 0; k < K_; k++) aqk += qp_i[k] * kmb[j * K_ + k];
        for (int v = 0; v < V_; v++) o_i[v] += aqk * vbb[j * V_ + v];
    }

    // Write o_i
    for (int v = 0; v < V_; v++) o_n[tid * st_c_v + v] = o_i[v];
    __syncthreads();

    // ---- Step 4: S = decay * (S + km^T @ vbar) ----
    for (int kk = tid; kk < K_; kk += C) {
        for (int v = 0; v < V_; v++) {
            float s = 0.0f;
            for (int j = 0; j < C; j++)
                s += kmb[j * K_ + kk] * vbb[j * V_ + v];
            S[kk * V_ + v] = decay[kk] * (S[kk * V_ + v] + s);
        }
    }
}
newString (5027 chars — TRUNCATED)
// ===========================================================================
// Per-chunk inter kernel — register-efficient, V-tiled.
//
// Uses V_TILE=32 to keep register pressure low.
// Grid: (B, H)  Block: C threads  Shared: 0 bytes
//
// Key to register efficiency:
//   - Process V in tiles of 32: only 32 floats in regs at a time
//   - Process K in streaming fashion: 1 float at a time
//   - max registers: vbar_tile(32) + o_tile(32) + aqk(1) + streams(~3) ≈ 70
// ===========================================================================
#define VT 32

__global__ void inter_chunk_kernel(
    const float* __restrict__ qp, const float* __restrict__ km,
    const float* __restrict__ w,  const float* __restrict__ u,
    const float* __restrict__ g,
    float* __restrict__ o,
    float* __restrict__ km_buf,   // (B, H, C, K) temp
    float* __restrict__ vb_buf,   // (B, H, C, V) temp
    float* __restrict__ S_global, // (B, H, K, V) state
    int B_, int H_, int NT, int K_, int V_,
    int chunk_n
) {
    int b = blockIdx.x, h = blockIdx.y;
    if (b >= B_ || h >= H_) return;
    int tid = threadIdx.x;

    int st_c_k = K_;
    int st_c_v = V_;
    int st_n_c_k = C * K_;
    int st_n_c_v = C * V_;
    int nvt = (V_ + VT - 1) / VT;  // number of V-tiles

    int bh = b * H_ + h;
    int cn = bh * NT + chunk_n;

    const float* qp_n = qp + cn * st_n_c_k;
    const float* km_n = km + cn * st_n_c_k;
    const float* w_n  = w  + cn * st_n_c_k;
    const float* u_n  = u  + cn * st_n_c_v;
    const float* g_n  = g  + cn * st_n_c_k;
    float* o_n        = o  + cn * st_n_c_v;

    float* kmb = km_buf + bh * C * K_;
    float* vbb = vb_buf + bh * C * V_;
    float* S = S_global + bh * K_ * V_;

    // ---- Decay ----
    float decay[128];
    for (int k = tid; k < K_; k += C) decay[k] = expf(g_n[(C - 1) * st_c_k + k]);

    // ---- Step 1: Write km_i to global temp ----
    for (int k = 0; k < K_; k++) kmb[tid * K_ + k] = km_n[tid * st_c_k + k];

    // ---- Step 2: vbar_i = u_i - w_i @ S, V-tiled ----
    for (int vt = 0; vt < nvt; vt++) {
        int v_off = vt * VT;
        int v_end = min(V_, v_off + VT);

        // Load u_i tile
        float vbar[VT];
        #pragma unroll
        for (int tv = 0; tv < VT; tv++) {
            int v = v_off + tv;
            vbar[tv] = (v < v_end) ? u_n[tid * st_c_v + v] : 0.0f;
        }

        // Subtract w @ S tile
        // Stream over K
        for (int k = 0; k < K_; k++) {
            float w_k = w_n[tid * st_c_k + k];
            #pragma unroll
            for (int tv = 0; tv < VT; tv++) {
                int v = v_off + tv;
                if (v < v_end) vbar[tv] -= w_k * S[k * V_ + v];
            }
        }

        // Write vbar tile to global temp
        #pragma unroll
        for (int tv = 0; tv < VT; tv++) {
            int v = v_off + tv;
            if (v < v_end) vbb[tid * V_ + v] = vbar[tv];
        }
    }

    __syncthreads();

    // ---- Step 3: o_i = qp_i @ S + sum_{j<tid} (qp_i @ km_j) * vbar_j ----
    for (int vt = 0; vt < nvt; vt++) {
        int v_off = vt * VT;
        int v_end = min(V_, v_off + VT);

        // qp_i @ S tile
        float o_tile[VT];
        #pragma unroll
        for (int tv = 0; tv < VT; tv++) o_tile[tv] = 0.0f;

        // Stream over K for qp_i @ S[tile]
        for (int k = 0; k < K_; k++) {
            float qp_k = qp_n[tid * st_c_k + k];
            #pragma unroll
            for (int tv = 0; tv < VT; tv++) {
                int v = v_off + tv;
                if (v < v_end) o_tile[tv] += qp_k * S[k * V_ + v];
            }
        }

        // Aqk @ vbar tile: sum_{j<tid} (qp_i @ km_j) * vbar_j[v]
        // For each j < tid: compute aqk_j (streaming over K), then scale vbar_j[tile]
        for (int j = 0; j < tid; j++) {
            float aqk = 0.0f;
            for (int k = 0; k < K_; k++)
                aqk += qp_n[tid * st_c_k + k] * kmb[j * K_ + k];
            #pragma unroll
            for (int tv = 0; tv < VT; tv++) {
  

... (1027 more chars)
tool
stdout (26 chars)
Edit applied successfully.
assistant
Let me just focus on rewriting the kernel properly with tiled V processing to avoid register spilling.
assistant
in 333out 3205cache_r 211200cache_w 0
assistant
bash
args
{
  "command": "<1002 chars \u2014 see below>",
  "description": "Test V-tiled kernel",
  "timeout": 60000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1002 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'
print('CUDA:', solution._cuda_module is not None)

init_args = solution.get_init_inputs()
ref_model = reference.Model(*init_args).to(device).eval()
sol_model = solution.Model(*init_args).to(device).eval()
sd = ref_model.state_dict()
sol_model.load_state_dict(sd, strict=True)

torch.manual_seed(42)
inputs = [t.to(device) for t in reference.get_inputs()]

with torch.no_grad():
    ref_out = ref_model(*inputs)
    sol_out = sol_model(*inputs)

diff = (ref_out.float() - sol_out.float()).abs()
print('max_diff:', diff.max().item(), 'PASS' if diff.max().item() < 0.05 else 'FAIL')

cuda_sync = torch.cuda.synchronize
for _ in range(3): sol_model(*inputs)
cuda_sync()
start = torch.cuda.Event(enable_timing=True)
end = torch.cuda.Event(enable_timing=True)
start.record()
for _ in range(20): sol_model(*inputs)
end.record()
cuda_sync()
ms = start.elapsed_time(end) / 20
print(f'ms={ms:.3f}')
" 2>&1
tool
stdout (47 chars)
CUDA: True
max_diff: 0.01171875 PASS
ms=27.216
assistant
in 58out 417cache_r 214784cache_w 0
assistant
todowrite
args
{
  "todos": [
    {
      "priority": "high",
      "content": "Fix PyTorch inter-chunk with pre-computed Aqk + bf16 matmuls",
      "status": "in_progress"
    },
    {
      "priority": "high",
      "content": "Verify correctness via check.py",
      "status": "pending"
    },
    {
      "priority": "medium",
      "content": "Benchmark and iterate for 10% peak fraction target",
      "status": "pending"
    }
  ]
}
tool
stdout (287 chars)
content: 'Fix PyTorch inter-chunk with pre-computed Aqk + bf16 matmuls'
status: 'in_progress'
priority: 'high'
content: 'Verify correctness via check.py'
status: 'pending'
priority: 'high'
content: 'Benchmark and iterate for 10% peak fraction target'
status: 'pending'
priority: 'medium'
assistant
The kernel approach is slower due to excessive global memory reads in nested loops. Let me go back to the PyTorch path (0.8ms) and optimize further.
assistant
in 135out 171cache_r 215168cache_w 0
assistant
edit /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (77 lines)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -1,41 +1,43 @@
-    # --- Pre-compute all Aqk in one batched call ---
-    # Aqk_all = q_plus @ k_minus^T  (B, H, NT, C, C), strict lower
+    # --- Pre-compute Aqk + derived in one batched call ---
     Aqk_all = torch.matmul(q_plus, k_minus.transpose(-2, -1))
     mask2 = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk_all.device), diagonal=1)
     Aqk_all = Aqk_all.masked_fill(mask2, 0.0)
 
-    # Pre-compute km * exp(g_last) for S update
-    # g[:,:,:,-1:,:] is the last g entry in each chunk
-    g_last_all = g[:, :, :, -1:, :]  # (B, H, NT, 1, K)
-    km_decayed = k_minus * g_last_all.exp()  # (B, H, NT, C, K)
+    g_last_all = g[:, :, :, -1:, :]
+    decay_all = g_last_all.exp()
+    km_decayed = k_minus * decay_all
 
-    # Also pre-compute decay per chunk
-    decay_all = g_last_all.exp().squeeze(-2).unsqueeze(-1)  # (B, H, NT, K, 1)
+    # Pre-compute qp - Aqk@w and Aqk@u per chunk (removes 2 bmm calls from loop)
+    # re_chunk = qp - Aqk @ w  and  bias_chunk = Aqk @ u
+    # Flatten to (B*H*NT, C, D) for single bmm calls
+    bh_nt = B * H * NT
+    Aqk_2d = Aqk_all.reshape(bh_nt, BT, BT)
+    w_2d = w.reshape(bh_nt, BT, K_)
+    u_2d = u.reshape(bh_nt, BT, V)
+    qp_2d = q_plus.reshape(bh_nt, BT, K_)
 
-    # --- Inter-chunk ---
+    # pre_w = Aqk @ w: (B*H*NT, C, C) @ (B*H*NT, C, K) = (B*H*NT, C, K)
+    pre_w = torch.bmm(Aqk_2d, w_2d)
+    q_eff = qp_2d - pre_w  # (B*H*NT, C, K)
+
+    # pre_u = Aqk @ u: (B*H*NT, C, C) @ (B*H*NT, C, V) = (B*H*NT, C, V)
+    pre_u = torch.bmm(Aqk_2d, u_2d)
+
+    q_eff = q_eff.reshape(B, H, NT, BT, K_)
+    pre_u = pre_u.reshape(B, H, NT, BT, V)
+    km_decayed = km_decayed.reshape(B, H, NT, BT, K_)
+    decay_all = decay_all.squeeze(-2).unsqueeze(-1)
+
+    # --- Inter-chunk loop (fused: 2 bmm/iter + 1 S update bmm) ---
     S = torch.zeros(B, H, K_, V, dtype=torch.float32, device=q.device)
-    qp_flat = q_plus.reshape(B * H, NT, BT, K_)
-    km_flat = k_minus.reshape(B * H, NT, BT, K_)
-    w_flat = w.reshape(B * H, NT, BT, K_)
-    u_flat = u.reshape(B * H, NT, BT, V)
-    o_flat = o.reshape(B * H, NT, BT, V)
-    decay_flat = decay_all.reshape(B * H, NT, K_, 1)
-    km_dec_flat = km_decayed.reshape(B * H, NT, BT, K_)
-    Aqk_flat = Aqk_all.reshape(B * H, NT, BT, BT)
+    for n in range(NT):
+        qe_n = q_eff[:, :, n]       # (B, H, C, K)
+        w_n = w[:, :, n]            # (B, H, C, K)
+        u_n = u[:, :, n]            # (B, H, C, V)
+        pu_n = pre_u[:, :, n]       # (B, H, C, V)
+        decay_n = decay_all[:, :, n]  # (B, H, K, 1)
+        kd_n = km_decayed[:, :, n]   # (B, H, C, K)
 
-    for n in range(NT):
-        qp_n = qp_flat[:, n]     # (B*H, C, K)
-        km_n = km_flat[:, n]     # (B*H, C, K)
-        w_n = w_flat[:, n]       # (B*H, C, K)
-        u_n = u_flat[:, n]       # (B*H, C, V)
-        Aqk_n = Aqk_flat[:, n]   # (B*H, C, C)
-        decay_n = decay_flat[:, n]  # (B*H, K, 1)
-
-        v_bar = u_n - torch.bmm(w_n, S.reshape(B * H, K_, V))
-        qS = torch.bmm(qp_n, S.reshape(B * H, K_, V))
-        o_flat[:, n] = qS + torch.bmm(Aqk_n, v_bar)
-
-        # S update
-        S = S.reshape(B * H, K_, V)
-        S = S * decay_n + torch.bmm(km_dec_flat[:, n].transpose(-2, -1), v_bar)
-        S = S.reshape(B, H, K_, V)+        v_bar = u_n - torch.matmul(w_n, S)              # 1 bmm
+        o[:, :, n] = torch.matmul(qe_n, S) + pu_n       # 1 bmm
+        S = S * decay_n + torch.matmul(kd_n.transpose(-2, -1), v_bar)  # 1 bmm
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "oldString": "<1795 chars \u2014 see below>",
  "newString": "<1879 chars \u2014 see below>"
}
oldString (1795 chars)
    # --- Pre-compute all Aqk in one batched call ---
    # Aqk_all = q_plus @ k_minus^T  (B, H, NT, C, C), strict lower
    Aqk_all = torch.matmul(q_plus, k_minus.transpose(-2, -1))
    mask2 = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk_all.device), diagonal=1)
    Aqk_all = Aqk_all.masked_fill(mask2, 0.0)

    # Pre-compute km * exp(g_last) for S update
    # g[:,:,:,-1:,:] is the last g entry in each chunk
    g_last_all = g[:, :, :, -1:, :]  # (B, H, NT, 1, K)
    km_decayed = k_minus * g_last_all.exp()  # (B, H, NT, C, K)

    # Also pre-compute decay per chunk
    decay_all = g_last_all.exp().squeeze(-2).unsqueeze(-1)  # (B, H, NT, K, 1)

    # --- Inter-chunk ---
    S = torch.zeros(B, H, K_, V, dtype=torch.float32, device=q.device)
    qp_flat = q_plus.reshape(B * H, NT, BT, K_)
    km_flat = k_minus.reshape(B * H, NT, BT, K_)
    w_flat = w.reshape(B * H, NT, BT, K_)
    u_flat = u.reshape(B * H, NT, BT, V)
    o_flat = o.reshape(B * H, NT, BT, V)
    decay_flat = decay_all.reshape(B * H, NT, K_, 1)
    km_dec_flat = km_decayed.reshape(B * H, NT, BT, K_)
    Aqk_flat = Aqk_all.reshape(B * H, NT, BT, BT)

    for n in range(NT):
        qp_n = qp_flat[:, n]     # (B*H, C, K)
        km_n = km_flat[:, n]     # (B*H, C, K)
        w_n = w_flat[:, n]       # (B*H, C, K)
        u_n = u_flat[:, n]       # (B*H, C, V)
        Aqk_n = Aqk_flat[:, n]   # (B*H, C, C)
        decay_n = decay_flat[:, n]  # (B*H, K, 1)

        v_bar = u_n - torch.bmm(w_n, S.reshape(B * H, K_, V))
        qS = torch.bmm(qp_n, S.reshape(B * H, K_, V))
        o_flat[:, n] = qS + torch.bmm(Aqk_n, v_bar)

        # S update
        S = S.reshape(B * H, K_, V)
        S = S * decay_n + torch.bmm(km_dec_flat[:, n].transpose(-2, -1), v_bar)
        S = S.reshape(B, H, K_, V)
newString (1879 chars)
    # --- Pre-compute Aqk + derived in one batched call ---
    Aqk_all = torch.matmul(q_plus, k_minus.transpose(-2, -1))
    mask2 = torch.triu(torch.ones(BT, BT, dtype=torch.bool, device=Aqk_all.device), diagonal=1)
    Aqk_all = Aqk_all.masked_fill(mask2, 0.0)

    g_last_all = g[:, :, :, -1:, :]
    decay_all = g_last_all.exp()
    km_decayed = k_minus * decay_all

    # Pre-compute qp - Aqk@w and Aqk@u per chunk (removes 2 bmm calls from loop)
    # re_chunk = qp - Aqk @ w  and  bias_chunk = Aqk @ u
    # Flatten to (B*H*NT, C, D) for single bmm calls
    bh_nt = B * H * NT
    Aqk_2d = Aqk_all.reshape(bh_nt, BT, BT)
    w_2d = w.reshape(bh_nt, BT, K_)
    u_2d = u.reshape(bh_nt, BT, V)
    qp_2d = q_plus.reshape(bh_nt, BT, K_)

    # pre_w = Aqk @ w: (B*H*NT, C, C) @ (B*H*NT, C, K) = (B*H*NT, C, K)
    pre_w = torch.bmm(Aqk_2d, w_2d)
    q_eff = qp_2d - pre_w  # (B*H*NT, C, K)

    # pre_u = Aqk @ u: (B*H*NT, C, C) @ (B*H*NT, C, V) = (B*H*NT, C, V)
    pre_u = torch.bmm(Aqk_2d, u_2d)

    q_eff = q_eff.reshape(B, H, NT, BT, K_)
    pre_u = pre_u.reshape(B, H, NT, BT, V)
    km_decayed = km_decayed.reshape(B, H, NT, BT, K_)
    decay_all = decay_all.squeeze(-2).unsqueeze(-1)

    # --- Inter-chunk loop (fused: 2 bmm/iter + 1 S update bmm) ---
    S = torch.zeros(B, H, K_, V, dtype=torch.float32, device=q.device)
    for n in range(NT):
        qe_n = q_eff[:, :, n]       # (B, H, C, K)
        w_n = w[:, :, n]            # (B, H, C, K)
        u_n = u[:, :, n]            # (B, H, C, V)
        pu_n = pre_u[:, :, n]       # (B, H, C, V)
        decay_n = decay_all[:, :, n]  # (B, H, K, 1)
        kd_n = km_decayed[:, :, n]   # (B, H, C, K)

        v_bar = u_n - torch.matmul(w_n, S)              # 1 bmm
        o[:, :, n] = torch.matmul(qe_n, S) + pu_n       # 1 bmm
        S = S * decay_n + torch.matmul(kd_n.transpose(-2, -1), v_bar)  # 1 bmm
assistant
Let me try the simplest optimization path — strip down to the fastest PyTorch version and use `torch.compile`.
assistant
in 930out 1676cache_r 215296cache_w 0
assistant
write /home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
diff (362 lines — TRUNCATED)
--- a//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
+++ b//home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py
@@ -1,7 +1,7 @@
-"""KDA forward (chunk form) — custom CUDA C++ kernel via load_inline.
-
-CUDA: intra-chunk correction + per-chunk inter kernel (no shared mem).
-PyTorch: reshape, elementwise exp/mul, initial matmuls.
+"""KDA forward (chunk form) — CUDA intra correction + optimized PyTorch inter.
+
+Reduces inter-chunk loop to 2 bmm calls per chunk (from 4) by pre-computing
+Aqk@u and (qp - Aqk@w) in batched bmms over all chunks.
 """
 from __future__ import annotations
 
@@ -15,9 +15,6 @@
 
 #define C 64
 
-// ===========================================================================
-// Intra-chunk triangular correction
-// ===========================================================================
 __global__ void intra_correction_kernel(
     float* __restrict__ A, int stride_A,
     const float* __restrict__ beta, int stride_beta,
@@ -32,7 +29,6 @@
 
     for (int j = 0; j < C; j++) sA[tid * C + j] = cA[tid * C + j];
     __syncthreads();
-
     for (int i = 1; i < C; i++) {
         if (tid < i) {
             float s = sA[i * C + tid];
@@ -42,163 +38,11 @@
         }
         __syncthreads();
     }
-
     for (int j = 0; j < C; j++) {
         float v = sA[tid * C + j];
         if (tid == j) v += 1.0f;
         v *= cB[j];
         cA[tid * C + j] = v;
-    }
-}
-
-// ===========================================================================
-// Per-chunk inter kernel — register-efficient, V-tiled.
-//
-// Uses V_TILE=32 to keep register pressure low.
-// Grid: (B, H)  Block: C threads  Shared: 0 bytes
-//
-// Key to register efficiency:
-//   - Process V in tiles of 32: only 32 floats in regs at a time
-//   - Process K in streaming fashion: 1 float at a time
-//   - max registers: vbar_tile(32) + o_tile(32) + aqk(1) + streams(~3) ≈ 70
-// ===========================================================================
-#define VT 32
-
-__global__ void inter_chunk_kernel(
-    const float* __restrict__ qp, const float* __restrict__ km,
-    const float* __restrict__ w,  const float* __restrict__ u,
-    const float* __restrict__ g,
-    float* __restrict__ o,
-    float* __restrict__ km_buf,   // (B, H, C, K) temp
-    float* __restrict__ vb_buf,   // (B, H, C, V) temp
-    float* __restrict__ S_global, // (B, H, K, V) state
-    int B_, int H_, int NT, int K_, int V_,
-    int chunk_n
-) {
-    int b = blockIdx.x, h = blockIdx.y;
-    if (b >= B_ || h >= H_) return;
-    int tid = threadIdx.x;
-
-    int st_c_k = K_;
-    int st_c_v = V_;
-    int st_n_c_k = C * K_;
-    int st_n_c_v = C * V_;
-    int nvt = (V_ + VT - 1) / VT;  // number of V-tiles
-
-    int bh = b * H_ + h;
-    int cn = bh * NT + chunk_n;
-
-    const float* qp_n = qp + cn * st_n_c_k;
-    const float* km_n = km + cn * st_n_c_k;
-    const float* w_n  = w  + cn * st_n_c_k;
-    const float* u_n  = u  + cn * st_n_c_v;
-    const float* g_n  = g  + cn * st_n_c_k;
-    float* o_n        = o  + cn * st_n_c_v;
-
-    float* kmb = km_buf + bh * C * K_;
-    float* vbb = vb_buf + bh * C * V_;
-    float* S = S_global + bh * K_ * V_;
-
-    // ---- Decay ----
-    float decay[128];
-    for (int k = tid; k < K_; k += C) decay[k] = expf(g_n[(C - 1) * st_c_k + k]);
-
-    // ---- Step 1: Write km_i to global temp ----
-    for (int k = 0; k < K_; k++) kmb[tid * K_ + k] = km_n[tid * st_c_k + k];
-
-    // ---- Step 2: vbar_i = u_i - w_i @ S, V-tiled ----
-    for (int vt = 0; vt < nvt; vt++) {
-        int v_off = vt * VT;
-        int v_end = min(V_, v_off + VT);
-
-        // Load u_i tile
-        float vbar[VT];
-        #pragma unroll
-        for (int tv = 0; tv < VT; tv++) {
-            int v = v_off + tv;
-            vbar[tv] = (v < v_end) ? u_n[tid * st_c_v + v] : 0.0f;
-        }
-
-        // Subtract w @ S tile
-        // Stream over K
-        for (int k = 0; k < K_; k++) {
-            float w_k = w_n[tid * st_c_k + k];
-            #pragma unroll
-            for (int tv = 0; tv < VT; tv++) {
-                int v = v_off + tv;
-                if (v < v_end) vbar[tv] -= w_k * S[k * V_ + v];
-            }
-        }
-
-        // Write vbar tile to global temp
-        #pragma unroll
-        for (int tv = 0; tv < VT; tv++) {
-            int v = v_off + tv;
-            if (v < v_end) vbb[tid * V_ + v] = vbar[tv];
-        }
-    }
-
-    __syncthreads();
-
-    // ---- Step 3: o_i = qp_i @ S + sum_{j<tid} (qp_i @ km_j) * vbar_j ----
-    for (int vt = 0; vt < nvt; vt++) {
-        int v_off = vt * VT;
-        int v_end = min(V_, v_off + VT);
-
-        // qp_i @ S tile
-        float o_tile[VT];
-        #pragma unroll
-        for (int tv = 0; tv < VT; tv++) o_tile[tv] = 0.0f;
-
-        // Stream over K for qp_i @ S[tile]
-        for (int k = 0; k < K_; k++) {
-            float qp_k = qp_n[tid * st_c_k + k];
-            #pragma unroll
-            for (int tv = 0; tv < VT; tv++) {
-                int v = v_off + tv;
-                if (v < v_end) o_tile[tv] += qp_k * S[k * V_ + v];
-            }
-        }
-
-        // Aqk @ vbar tile: sum_{j<tid} (qp_i @ km_j) * vbar_j[v]
-        // For each j < tid: compute aqk_j (streaming over K), then scale vbar_j[tile]
-        for (int j = 0; j < tid; j++) {
-            float aqk = 0.0f;
-            for (int k = 0; k < K_; k++)
-                aqk += qp_n[tid * st_c_k + k] * kmb[j * K_ + k];
-            #pragma unroll
-            for (int tv = 0; tv < VT; tv++) {
-                int v = v_off + tv;
-                if (v < v_end) o_tile[tv] += aqk * vbb[j * V_ + v];
-            }
-        }
-
-        // Write o tile
-        #pragma unroll
-        for (int tv = 0; tv < VT; tv++) {
-            int v = v_off + tv;
-            if (v < v_end) o_n[tid * st_c_v + v] = o_tile[tv];
-        }
-    }
-    __syncthreads();
-
-    // ---- Step 4: S = decay * (S + km^T @ vbar) ----
-    // E

... (6103 more chars)
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass/solution.py",
  "content": "<6354 chars \u2014 see diff>"
}
tool
stdout (24 chars)
Wrote file successfully.
assistant
in 37out 2375cache_r 219648cache_w 0
assistant
bash
args
{
  "command": "<1034 chars \u2014 see below>",
  "description": "Test optimized PyTorch inter-chunk",
  "timeout": 30000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1034 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'
torch.set_float32_matmul_precision('high')

init_args = solution.get_init_inputs()
ref_model = reference.Model(*init_args).to(device).eval()
sol_model = solution.Model(*init_args).to(device).eval()
sd = ref_model.state_dict()
sol_model.load_state_dict(sd, strict=True)

torch.manual_seed(42)
torch.cuda.manual_seed_all(42)
inputs = [t.to(device) for t in reference.get_inputs()]

with torch.no_grad():
    ref_out = ref_model(*inputs)
    sol_out = sol_model(*inputs)

diff = (ref_out.float() - sol_out.float()).abs()
print('PASS' if diff.max().item() < 0.05 else 'FAIL', f'max_diff={diff.max().item():.6f}')

# Benchmark
for _ in range(3): sol_model(*inputs)
torch.cuda.synchronize()
start = torch.cuda.Event(enable_timing=True)
end = torch.cuda.Event(enable_timing=True)
start.record()
for _ in range(20): sol_model(*inputs)
end.record()
torch.cuda.synchronize()
ms = start.elapsed_time(end) / 20
print(f'ms={ms:.3f}')
" 2>&1
tool
stdout (32 chars)
PASS max_diff=0.000061
ms=0.790
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0.79ms, correct to 6e-5. Let me try torch.compile, then run check.py.
assistant
bash
args
{
  "command": "<748 chars \u2014 see below>",
  "description": "Try torch.compile for speedup",
  "timeout": 120000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (748 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'
torch.set_float32_matmul_precision('high')

init_args = solution.get_init_inputs()
model = solution.Model(*init_args).to(device).eval()

compiled = torch.compile(model, mode='max-autotune', fullgraph=True)

torch.manual_seed(42)
torch.cuda.manual_seed_all(42)
inputs = [t.to(device) for t in solution.get_inputs()]

# Warmup + compile
compiled(*inputs)
torch.cuda.synchronize()

# Benchmark
start = torch.cuda.Event(enable_timing=True)
end = torch.cuda.Event(enable_timing=True)
start.record()
for _ in range(20): compiled(*inputs)
end.record()
torch.cuda.synchronize()
ms = start.elapsed_time(end) / 20
print(f'compiled ms={ms:.3f}')
" 2>&1
tool
stdout (3696 chars) — TRUNCATED
/home/infatoshi/.local/lib/python3.12/site-packages/torch/_dynamo/variables/functions.py:2082: UserWarning: Dynamo does not know how to trace the builtin `kda_cutlass_cu.pybind11_detail_function_record_v1_system_libstdcpp_gxx_abi_1xxx_use_cxx11_abi_1.kda_correction.` This function is either a Python builtin (e.g. _warnings.warn) or a third-party C/C++ Python extension (perhaps created with pybind).
If it is a Python builtin, please file an issue on GitHub so the PyTorch team can add support for it and see the next case for a workaround.
If it is a third-party C/C++ Python extension, please either wrap it into a PyTorch-understood custom operator (see https://pytorch.org/tutorials/advanced/custom_ops_landing_page.html for more details) or, if it is traceable, use `torch.compiler.allow_in_graph`.
  torch._dynamo.utils.warn_once(explanation + "\n" + "\n".join(hints))
Traceback (most recent call last):
  File "<string>", line 19, in <module>
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/_dynamo/eval_frame.py", line 472, in __call__
    return super().__call__(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1779, in _wrapped_call_impl
    return self._call_impl(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/infatoshi/.local/lib/python3.12/site-packages/torch/nn/modules/module.py", line 1790, in _call_impl
    return forward_cal

... (2196 more chars)
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in 37out 366cache_r 222592cache_w 0
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torch.compile can't trace the custom CUDA op. Let me try bf16 matmuls for the pre-computation and check the speed.
assistant
bash
args
{
  "command": "<1686 chars \u2014 see below>",
  "description": "Benchmark all shapes",
  "timeout": 60000,
  "workdir": "/home/infatoshi/cuda/KernelBench-Hard/problems/02_kda_cutlass"
}
command (1686 chars)
python -c "
import sys; sys.path.insert(0, '.')
import solution, reference
import torch

device = 'cuda:0'
torch.set_float32_matmul_precision('high')

init_args = solution.get_init_inputs()
ref_model = reference.Model(*init_args).to(device).eval()
sol_model = solution.Model(*init_args).to(device).eval()
sd = ref_model.state_dict()
sol_model.load_state_dict(sd, strict=True)

torch.manual_seed(42)
inputs = [t.to(device) for t in reference.get_inputs()]

# Test bf16 matmuls in the pre-computation by modifying _kda_chunk_forward
# For now, just benchmark the current fp32 version on all shapes
import time

for shape_idx, shape_name, B,T,H,K,V in [
    (0, 'B2_T1024_H8', 2, 1024, 8, 128, 128),
    (1, 'B2_T2048_H8', 2, 2048, 8, 128, 128),
    (2, 'B1_T4096_H8', 1, 4096, 8, 128, 128),
    (3, 'B1_T2048_H4', 1, 2048, 4, 128, 128),
]:
    m = solution.Model(B, T, H, K, V, 64).to(device).eval()
    q = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
    k = torch.randn(B, T, H, K, dtype=torch.bfloat16, device=device) * 0.1
    v = torch.randn(B, T, H, V, dtype=torch.bfloat16, device=device) * 0.1
    g = torch.randn(B, T, H, K, dtype=torch.float32, device=device) * 0.1 - 0.05
    beta = torch.sigmoid(torch.randn(B, T, H, dtype=torch.bfloat16, device=device))
    inputs = [q, k, v, g, beta]
    
    for _ in range(3): m(*inputs)
    torch.cuda.synchronize()
    start = torch.cuda.Event(enable_timing=True)
    end = torch.cuda.Event(enable_timing=True)
    start.record()
    for _ in range(20): m(*inputs)
    end.record()
    torch.cuda.synchronize()
    ms = start.elapsed_time(end) / 20
    print(f'shape={shape_idx} {shape_name}: {ms:.3f} ms')
" 2>&1
tool
stdout (120 chars)
shape=0 B2_T1024_H8: 0.788 ms
shape=1 B2_T2048_H8: 1.363 ms
shape=2 B1_T4096_H8: 2.529 ms
shape=3 B1_T2048_H4: 1.363 ms
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