cursor / Composer 2.5 Fast session: d04a3e12-fde2-4e7b-a958-71fa7faf1b73 cwd: /workspace/problems/01_fp8_gemm
harness
cursor
model
Composer 2.5 Fast
turns
76
tools called
61
events
140
input toks
61,080
output toks
31,116
cache hit
1,122,545
duration
338.7s
solution.py
final answer
benchmark.log
check.log
result.json
"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
import torch
import torch.nn as nn
import triton
import triton.language as tl

E4M3_MAX = 448.0


@triton.jit
def _fp8_gemm_kernel(
    A,
    B,
    C,
    Scales,
    M,
    N,
    K,
    stride_am,
    stride_ak,
    stride_bk,
    stride_bn,
    stride_cm,
    stride_cn,
    BLOCK_M: tl.constexpr,
    BLOCK_N: tl.constexpr,
    BLOCK_K: tl.constexpr,
    GROUP_M: tl.constexpr,
    NUM_STAGES: tl.constexpr,
):
    pid = tl.program_id(0)
    num_pid_m = tl.cdiv(M, BLOCK_M)
    num_pid_n = tl.cdiv(N, BLOCK_N)
    num_pid_in_group = GROUP_M * num_pid_n
    group_id = pid // num_pid_in_group
    first_pid_m = group_id * GROUP_M
    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
    pid_m = first_pid_m + (pid % group_size_m)
    pid_n = (pid % num_pid_in_group) // group_size_m

    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
    offs_k = tl.arange(0, BLOCK_K)

    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn

    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
    for k in tl.range(0, K, BLOCK_K, num_stages=NUM_STAGES):
        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
        acc = tl.dot(a, b, acc)
        a_ptrs += BLOCK_K * stride_ak
        b_ptrs += BLOCK_K * stride_bk

    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
    acc = acc * scales[None, :]

    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))


@triton.jit
def _fp8_gemm_skinny_kernel(
    A,
    B,
    C,
    Scales,
    M,
    N,
    K,
    stride_am,
    stride_ak,
    stride_bk,
    stride_bn,
    stride_cm,
    stride_cn,
    BLOCK_M: tl.constexpr,
    BLOCK_N: tl.constexpr,
    BLOCK_K: tl.constexpr,
    NUM_STAGES: tl.constexpr,
):
    pid_n = tl.program_id(0)
    offs_m = tl.arange(0, BLOCK_M)
    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
    offs_k = tl.arange(0, BLOCK_K)

    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn

    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
    for k in tl.range(0, K, BLOCK_K, num_stages=NUM_STAGES):
        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
        acc = tl.dot(a, b, acc)
        a_ptrs += BLOCK_K * stride_ak
        b_ptrs += BLOCK_K * stride_bk

    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
    acc = acc * scales[None, :]

    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))


def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
    if M <= 64:
        return 32, 128, 256, 4, 3, 1
    if N >= 12000:
        return 128, 256, 128, 8, 3, 4
    return 128, 256, 128, 8, 3, 4


def _fp8_gemm(
    x: torch.Tensor,
    weight: torch.Tensor,
    weight_scale: torch.Tensor,
    M: int,
) -> torch.Tensor:
    K = x.shape[1]
    N, K_w = weight.shape
    assert K == K_w

    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
    block_m, block_n, block_k, num_warps, num_stages, group_m = _pick_config(M, N)

    if M <= 64:
        grid = (triton.cdiv(N, block_n),)
        _fp8_gemm_skinny_kernel[grid](
            x,
            weight,
            y,
            weight_scale,
            M,
            N,
            K,
            x.stride(0),
            x.stride(1),
            weight.stride(1),
            weight.stride(0),
            y.stride(0),
            y.stride(1),
            BLOCK_M=block_m,
            BLOCK_N=block_n,
            BLOCK_K=block_k,
            NUM_STAGES=num_stages,
            num_warps=num_warps,
        )
    else:
        grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
        _fp8_gemm_kernel[grid](
            x,
            weight,
            y,
            weight_scale,
            M,
            N,
            K,
            x.stride(0),
            x.stride(1),
            weight.stride(1),
            weight.stride(0),
            y.stride(0),
            y.stride(1),
            BLOCK_M=block_m,
            BLOCK_N=block_n,
            BLOCK_K=block_k,
            GROUP_M=group_m,
            NUM_STAGES=num_stages,
            num_warps=num_warps,
        )
    return y


class Model(nn.Module):
    def __init__(self, M: int, N: int, K: int):
        super().__init__()
        self.M, self.N, self.K = M, N, K
        w = torch.empty(N, K, dtype=torch.bfloat16)
        nn.init.normal_(w, std=0.02)
        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
        self.register_buffer("weight", w_fp8)
        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
        self._weight_padded: torch.Tensor | None = None
        self._weight_version: int = -1

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        K = x.shape[1]
        pad_k = (128 - (K % 128)) % 128
        if pad_k:
            if self._weight_padded is None or self._weight_version != self.weight._version:
                self._weight_padded = torch.nn.functional.pad(self.weight, (0, pad_k))
                self._weight_version = self.weight._version
            x = torch.nn.functional.pad(x, (0, pad_k))
            weight = self._weight_padded
        else:
            weight = self.weight
        return _fp8_gemm(x, weight, self.weight_scale, self.M)


M = 4096
N = 4096
K = 4096


def get_inputs():
    x = (torch.rand(M, K) * 8 - 4).to(torch.float8_e4m3fn)
    return [x]


def get_init_inputs():
    return [M, N, K]
I'll start by reading the reference implementation and workspace layout, then build and iterate on an FP8 tensor-core GEMM in `solution.py`. I'll probe Triton FP8 dot and CUDA FP8 MMA support on this GPU, then inspect any existing reference kernels in the repo. Triton FP8 dot works. I'll implement a full GEMM kernel with per-channel scaling and verify correctness. The kernel failed to compile with larger block sizes. I'll simplify the tile configuration and retest. The mask shapes were wrong — I'll fix them to match the working test pattern. Correctness passes. Next I'll benchmark and tune tile sizes and kernel config for throughput. Shape 1 (K=4127) is far too slow — I'll dig into that regression and tune tile sizes for the other shapes. The slowdown comes from K not being divisible by 128 — I'll split the kernel into a full-tile main loop and a masked epilogue. Autotune likely picked an incorrect config — I'll switch to fixed, validated tile sizes. Padding K to a multiple of 128 with zeros should let us use the fast no-tail kernel on K=4127. K=4127 is fixed. Next I'll tune the skinny decode shape and push compute-bound cases toward higher TFLOPS. Weight pre-padding breaks `state_dict` loading — I'll pad at runtime instead while keeping the registered buffers unchanged. Cleaning up the kernels and adding a padded-weight cache to squeeze out more performance. The padded-weight cache goes stale under numeric stress — I'll invalidate it when weights change. Implemented a Triton FP8 tensor-core GEMM in `solution.py`. `check.py` passes and benchmark results are below. ## Approach **Kernel:** Two Triton kernels using `tl.dot` on `float8_e4m3fn` with fp32 accumulation, then per-channel `weight_scale`, output as bf16. 1. **`_fp8_gemm_kernel`** — general case with L2-swizzled 1D grid (`GROUP_M` reordering) 2. **`_fp8_gemm_skinny_kernel`** — decode path (`M ≤ 64`), parallelized over N only **Key optimizations:** - **K-padding to 128** — When `K % 128 ≠ 0` (e.g. K=4127), pad x and weight with fp8 zeros so the inner loop never needs predicated K tails. Masked tails broke Triton pipelining and caused a ~10× slowdown. - **`tl.range(..., num_stages=3)`** — Software pipelining for HBM latency hiding - **Shape-specific tiles:** - Square / Llama: `128×256×128`, 8 warps, 3 stages - Skinny decode: `32×128×256`, 4 warps, 3 stages - **Cached padded weight** — Invalidated via `weight._version` for numeric-stress cases ## Results (`benchmark.py`) | Shape | TFLOPS | Peak Fraction | Notes | |-------|--------|---------------|-------| | 4096³ | **610** | 61.0% | vs cuBLAS SOTA ~541 | | 4096³ K=4127 | **534** | 53.5% | cuBLAS `_scaled_mm` fails (K%16≠0) | | 32×8192×8192 | **73** | 7.3% | 1151 GB/s (64% DRAM peak); memory-bound | | 4096×14336×4096 | **671** | 67.1% | vs SOTA ~654 | **Geomean peak_fraction: 0.355** (35.5% of 1000 TFLOPS FP8 roofline) The solution beats the cuBLAS SOTA baseline on every shape where SOTA runs, and handles K=4127 which cuBLAS cannot.
warning: `VIRTUAL_ENV=/home/infatoshi/kernelbench.com/benchmarks/hard/.venv` does not match the project environment path `/home/infatoshi/kernelbench.com/benchmarks/hard/outputs/runs/20260615_114532_cursor_composer-2.5-fast_01_fp8_gemm/repo/.venv` and will be ignored; use `--active` to target the active environment instead
benchmark_event event=variant_start shape=0 variant=solution ts=2026-06-15T18:03:56.203594+00:00
benchmark_event event=variant_end shape=0 variant=solution ts=2026-06-15T18:03:56.616695+00:00 elapsed_s=0.413 ms=0.219136
shape=0 variant=solution tflops=627.186 gbps=306.243 ms=0.219
shape=0 solution_peak_fraction=0.6272
benchmark_event event=variant_start shape=1 variant=solution ts=2026-06-15T18:03:57.165588+00:00
benchmark_event event=variant_end shape=1 variant=solution ts=2026-06-15T18:03:57.326882+00:00 elapsed_s=0.161 ms=0.254816
shape=1 variant=solution tflops=543.448 gbps=264.359 ms=0.255
shape=1 solution_peak_fraction=0.5434
benchmark_event event=variant_start shape=2 variant=solution ts=2026-06-15T18:03:59.311997+00:00
benchmark_event event=variant_end shape=2 variant=solution ts=2026-06-15T18:03:59.496462+00:00 elapsed_s=0.184 ms=0.048112
shape=2 variant=solution tflops=89.270 gbps=1411.193 ms=0.048
shape=2 solution_peak_fraction=0.0893
benchmark_event event=variant_start shape=3 variant=solution ts=2026-06-15T18:04:01.294873+00:00
benchmark_event event=variant_end shape=3 variant=solution ts=2026-06-15T18:04:01.524438+00:00 elapsed_s=0.230 ms=0.725008
shape=3 variant=solution tflops=663.491 gbps=266.118 ms=0.725
shape=3 solution_peak_fraction=0.6635
peak_fraction: 0.3769
RESULT: OK
warning: `VIRTUAL_ENV=/home/infatoshi/kernelbench.com/benchmarks/hard/.venv` does not match the project environment path `/home/infatoshi/kernelbench.com/benchmarks/hard/outputs/runs/20260615_114532_cursor_composer-2.5-fast_01_fp8_gemm/repo/.venv` and will be ignored; use `--active` to target the active environment instead
warning: Ignoring existing virtual environment linked to non-existent Python interpreter: /home/infatoshi/kernelbench.com/benchmarks/hard/outputs/runs/20260615_114532_cursor_composer-2.5-fast_01_fp8_gemm/repo/.venv/bin/python3 -> python
Using CPython 3.11.15
Removed virtual environment at: /home/infatoshi/kernelbench.com/benchmarks/hard/outputs/runs/20260615_114532_cursor_composer-2.5-fast_01_fp8_gemm/repo/.venv
Creating virtual environment at: /home/infatoshi/kernelbench.com/benchmarks/hard/outputs/runs/20260615_114532_cursor_composer-2.5-fast_01_fp8_gemm/repo/.venv
   Building kernelbench-hard @ file:///home/infatoshi/kernelbench.com/benchmarks/hard/outputs/runs/20260615_114532_cursor_composer-2.5-fast_01_fp8_gemm/repo
      Built kernelbench-hard @ file:///home/infatoshi/kernelbench.com/benchmarks/hard/outputs/runs/20260615_114532_cursor_composer-2.5-fast_01_fp8_gemm/repo
Installed 56 packages in 193ms
PASS
{
    "run_id": "20260615_114532_cursor_composer-2.5-fast_01_fp8_gemm",
    "run_group": "",
    "problem": "01_fp8_gemm",
    "harness": "cursor",
    "model": "composer-2.5-fast",
    "reasoning_effort": "",
    "started_at": "2026-06-15T11:45:32-06:00",
    "harness_finished_at": "2026-06-15T11:51:15-06:00",
    "finished_at": "2026-06-15T12:04:01-06:00",
    "start_epoch": 1781545532,
    "harness_end_epoch": 1781545875,
    "end_epoch": 1781546641,
    "has_solution": true,
    "correct": true,
    "failure_reason": "pass",
    "retryable_infra_failure": false,
    "minimum_useful_output_tokens": 5000,
    "peak_fraction": 0.3769,
    "template_mutated": false,
    "elapsed_seconds": 343,
    "total_elapsed_seconds": 1109,
    "check_elapsed_seconds": 759,
    "benchmark_elapsed_seconds": 7,
    "check_timeout_seconds": 180,
    "benchmark_timeout_seconds": 1800,
    "check_exit_code": 0,
    "benchmark_exit_code": 0,
    "harness_exit_code": 0,
    "session_complete": true,
    "agent_cuda_disabled": false,
    "agent_container": true,
    "agent_container_image": "nvcr.io/nvidia/tensorrt-llm/release:latest",
    "agent_container_network": "bridge",
    "gpu_queue_mode": "agent_container_native_profiling_path_wrapper_gpu_lock",
    "output_tokens_per_second": 90.71720116618076,
    "usage": {"input_tokens": 61080, "output_tokens": 31116, "cache_read_tokens": 1122545, "cache_creation_tokens": 0, "reasoning_tokens": null, "total_cost_usd": null}
}

timeline (140 events)

system — init
session start cwd=/workspace/problems/01_fp8_gemm model=Composer 2.5 Fast permissions=default
user
I need you to optimize an FP8 GEMM for the RTX PRO 6000 (SM120 Blackwell, GDDR7, 1.8 TB/s). The reference implementation is in reference.py and your kernel goes in solution.py. You can make whatever mess you want in this directory — scratch files, intermediate kernels, build artifacts, profiling traces — but the final answer has to be in solution.py with the same Model, get_inputs, and get_init_inputs interface as reference.py. This is a genuine fp8 x fp8 GEMM. Both operands are fp8_e4m3. The activation x is fp8_e4m3 (M, K). The weight is given to you ALREADY quantized: the Model holds `weight` as fp8_e4m3 (N, K) normalized into the e4m3 range, plus `weight_scale` (N,), a per-output-channel dequant scale. You return y = (x @ weight.T) * weight_scale as bf16 (M, N). Read reference.py — it defines this exactly; your Model must register the same `weight` and `weight_scale` buffers so the graded state_dict loads. To actually score well you must run a real fp8 x fp8 tensor-core MMA (fp8 inputs, fp32 accumulate) and apply the per-channel scale. Upcasting both operands to bf16 and doing a bf16 GEMM is correct but it caps at roughly HALF the roofline — the roofline here is the fp8 peak (~1000 TFLOPS) and bf16 tensor cores run at ~half that. So a bf16 fallback passes correctness but leaves ~2x on the table; the fp8 path is the point. Correctness tolerance on the bf16 output is ~0.2 abs/rel (fp8 has real accumulation noise, so the bar is loose), but it has to match the reference within that across every shape and the numeric-stress cases. The shapes you must handle are M=4096 N=4096 K=4096 (square aligned, the easy case), M=4096 N=4096 K=4127 (K not a multiple of 128, which forces predicated tails on tile-quantized kernels), M=32 N=8192 K=8192 (skinny M, decode-style, memory-bound), and M=4096 N=14336 K=4096 (Llama-3 up-proj). This needs to be a real custom kernel. Don't reach for torch._scaled_mm or torch.ops.aten._scaled_mm — they're off-limits and using them fails correctness. Triton tl.dot on fp8, CUDA C++ via torch.utils.cpp_extension.load_inline, inline PTX (mma.sync ... e4m3), or CUTLASS all work — whatever fits. Anything you're uncertain about, look up PTX docs, clone CUTLASS or other reference repos, read library headers, and investigate. Your flywheel is implement, profile (ncu, nsys, torch.profiler — whatever's useful) and time it with benchmark.py, verify correctness by running `python check.py` and reading the output, then iterate. Don't substitute your own one-off correctness snippets for check.py — it iterates over every shape, your spot-check almost certainly won't. If `python check.py` hasn't printed PASS, you're not done. Take as long as you need to actually push the number up. Workspace isolation note: you are already running inside the archive-local problem workspace, /workspace/problems/01_fp8_gemm. Write the final answer to solution.py in the current directory only. The source repository's problems/ tree is not mounted. Container note: inside this run, the visible workspace path is /workspace/problems/01_fp8_gemm. The source repository, old runs, leaderboards, and host harness memory are not mounted. Container network mode is bridge. Run all Python through `uv run ...` so you use the workspace uv environment; it is built from the same uv.lock as the official scoring environment. The container image's system python has a different torch build and is NOT the scoring environment.
assistant
I'll start by reading the reference implementation and workspace layout, then build and iterate on an FP8 tensor-core GEMM in `solution.py`.
assistant
glob
args
{
  "targetDirectory": "/workspace/problems/01_fp8_gemm",
  "globPattern": "**/*"
}
assistant
read /workspace/problems/01_fp8_gemm/reference.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/reference.py"
}
tool
stdout (4 chars)
null
assistant
read /workspace/problems/01_fp8_gemm/solution.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py"
}
tool
stdout (1950 chars) — TRUNCATED
"""FP8 e4m3 GEMM reference (correctness only, NOT the SOTA baseline).

Genuine fp8 x fp8: BOTH operands are fp8_e4m3. The weight is stored as fp8
(normalized into the e4m3 range) together with a per-output-channel scale, the
standard scaled-fp8 inference layout. The reference upcasts the fp8 operands to
bf16 and matmuls, then applies the per-channel scale — this DEFINES the fp8
target. A real fp8 x fp8 MMA kernel matches it (and can exceed the bf16 roofline
ceiling of ~0.5); a bf16-upcast kernel also matches but stays capped at ~0.5.
"""
import torch
import torch.nn as nn

OP_TYPE = "gemm"
SUPPORTED_PRECISIONS = ["fp8_e4m3"]
HARDWARE_REQUIRED = ["RTX_PRO_6000", "H100", "B200"]
E4M3_MAX = 448.0


class Model(nn.Module):
    """y = ((x @ w.T) * weight_scale).to(bf16).

    x: fp8_e4m3 (M, K).  w: fp8_e4m3 (N, K) normalized to the e4m3 range.
    weight_scale: (N,) per-output-channel dequant scale.
    """

    def __init__(self, M: int, N: int, K: int):
        super().__init__()
        self.M, self.N, self.K = M, N, K
        w = torch.empty(N, K, dtype=torch.bfloat16)
        nn.init.normal_(w, std=0.02)
        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)  # (N,1)
        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
        self.register_buffer("weight", w_fp8)                         # (N, K) fp8
        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))  # (N,)

    def forward(self, x: torch.Tensor) -> torch.Tensor:
   

... (450 more chars)
assistant
read /workspace/problems/01_fp8_gemm/check.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/check.py"
}
tool
stderr (30 chars)
errorMessage: 'File not found'
assistant
read /workspace/problems/01_fp8_gemm/benchmark.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/benchmark.py"
}
tool
stdout (4203 chars) — TRUNCATED
"""Correctness runner for FP8 GEMM.

Runs solution.Model vs reference.Model across all shapes in shapes.py, 3 seeds
each, with per-dtype atol/rtol. Also rejects forbidden ops by grep.
"""
import re
import sys
from pathlib import Path

import torch
import yaml

# Make the repo's src/ importable
REPO_ROOT = Path(__file__).resolve().parents[2]
sys.path.insert(0, str(REPO_ROOT))

from src.eval.correctness import check_correctness  # noqa: E402
from src.eval.numeric_stress import (  # noqa: E402
    numeric_stress_cases,
    numeric_stress_context,
    tolerance_for_case,
)


def main():
    try:
        import reference
        import shapes
        import solution
    except Exception as e:
        print(f"FAIL: import error: {e}")
        sys.exit(1)

    problem_yaml = Path("problem.yaml")
    meta = yaml.safe_load(problem_yaml.read_text()) if problem_yaml.exists() else {}

    # --- Forbidden-op check ------------------------------------------------
    sol_src = Path("solution.py").read_text() if Path("solution.py").exists() else ""
    for forbidden in meta.get("forbidden", []):
        pat = re.escape(forbidden)
        if re.search(pat, sol_src):
            print(f"FAIL: forbidden op used: {forbidden}")
            sys.exit(1)

    device = torch.device("cuda:0")
    tol_override = meta.get("tolerance") or None

    # --- Per-shape correctness --------------------------------------------
    all_shapes = shapes.SHAPES
    for shape_idx, shape in enumerate(all_shapes):
  

... (2703 more chars)
tool
stdout (5147 chars) — TRUNCATED
"""Roofline benchmark for FP8 GEMM.

For each shape: times the agent's solution first. Optional eager, compiled,
and SOTA diagnostics are enabled with KBH_BENCHMARK_BASELINES=1. Reports achieved TFLOPS, GB/s, and peak_fraction.

Output lines the harness picks up:
  shape=<idx> variant=<name> tflops=<N> gbps=<N> ms=<N>
  peak_fraction: <N>  (geomean over shapes of solution's peak_fraction)
"""
import sys
from math import exp, log
from pathlib import Path

import torch
import yaml

REPO_ROOT = Path(__file__).resolve().parents[2]
sys.path.insert(0, str(REPO_ROOT))

from src.eval.roofline import compute_gbps, compute_tflops, peak_fraction  # noqa: E402
from src.eval.timing import benchmark_baselines_enabled, time_variant  # noqa: E402
from src.hardware import get as get_hw  # noqa: E402


def _eval_formula(expr: str, vars: dict) -> float:
    # Very small eval: only names from `vars` are valid.
    return float(eval(expr, {"__builtins__": {}}, vars))


def main():
    import reference
    import shapes
    import solution

    meta = yaml.safe_load(Path("problem.yaml").read_text())
    hw = get_hw(meta["hardware"][0])
    peak_tflops = hw.peak_tflops_dense.get(meta["peak_tflops_key"], 0.0)
    peak_gbps = hw.peak_bandwidth_gb_s
    regime = meta.get("regime", "compute")
    flops_formula = meta["flops_formula"]
    bytes_formula = meta["bytes_formula"]
    num_perf_trials = int(meta.get("num_perf_trials", 30))

    device = torch.device("cuda:0")
    include_baselines = benchmark

... (3647 more chars)
assistant
read /workspace/problems/01_fp8_gemm/shapes.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/shapes.py"
}
assistant
read /workspace/problems/01_fp8_gemm/problem.yaml
args
{
  "path": "/workspace/problems/01_fp8_gemm/problem.yaml"
}
assistant
read /workspace/problems/01_fp8_gemm/sota.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/sota.py"
}
tool
stdout (564 chars)
"""Canonical shape sweep for FP8 GEMM.

Mix of:
  - square aligned (the easy case)
  - off-alignment K (common real-world failure mode for tile-quantized kernels)
  - skinny (decode-like, memory-bound)
  - rectangular (prefill with grouped attention)
"""

SHAPES = [
    {"M": 4096, "N": 4096, "K": 4096},        # square aligned
    {"M": 4096, "N": 4096, "K": 4127},        # K not multiple of 128 -> forces predicated tails
    {"M": 32,   "N": 8192, "K": 8192},        # skinny M (decode)
    {"M": 4096, "N": 14336, "K": 4096},       # Llama3 up-proj shape
]
tool
stdout (1141 chars)
name: 01_fp8_gemm
display_name: "FP8 e4m3 GEMM"
precision: fp8_e4m3
regime: compute

# Dense-equivalent FLOPs per invocation. Evaluated per-shape; the benchmark
# substitutes M/N/K from each shapes.py entry.
flops_formula: "2 * M * N * K"

# Bytes moved (approximate): fp8 inputs in, bf16 output.
bytes_formula: "M*K + K*N + M*N*2"

hardware: [RTX_PRO_6000]
peak_tflops_key: fp8  # index into src/hardware/rtx_pro_6000.py peak_tflops_dense
peak_bandwidth_key: dram

# Per-dtype tolerance override (optional). Defaults are in src/eval/correctness.py.
tolerance:
  bfloat16: 0.2
  fp8_e4m3fn: 0.2

# Forbidden ops — using any of these in solution.py fails correctness post-hoc.
# torch._scaled_mm is Stanford-style cheating (just call the vendor library).
forbidden:
  - "torch._scaled_mm"
  - "torch.ops.aten._scaled_mm"

sota:
  name: "FlashInfer FP8 GEMM"
  url: "https://github.com/flashinfer-ai/flashinfer"
  function: "flashinfer.gemm.fp8_gemm"
  deps:
    - "flashinfer>=0.6.8"
  # Documented H100 throughput for this shape (informational, not graded):
  reference_throughput_tflops_h100: 550

num_correct_trials: 3
num_perf_trials: 30
tool
stdout (1723 chars) — TRUNCATED
"""SOTA reference for FP8 GEMM: flashinfer.gemm.fp8_gemm.

If flashinfer is not installed or the SM120 path isn't supported, this falls
back to torch._scaled_mm which is the cuBLAS FP8 path. The benchmark treats
whichever succeeds as the SOTA reference line.

Agents are FORBIDDEN from using torch._scaled_mm in their solution (see
problem.yaml.forbidden). This file is only for the benchmark's reference line.
"""
from __future__ import annotations

import torch


def _try_flashinfer(x: torch.Tensor, w: torch.Tensor) -> torch.Tensor | None:
    try:
        import flashinfer  # noqa: F401
        # Note: flashinfer's FP8 GEMM API surface may differ; adapt if needed.
        # Placeholder call — replace with the actual flashinfer entry point
        # once validated on SM120.
        return None
    except ImportError:
        return None


def _scaled_mm(x: torch.Tensor, w: torch.Tensor) -> torch.Tensor:
    # torch._scaled_mm wants per-tensor scales. Use unit scales for the reference.
    scale_a = torch.tensor(1.0, device=x.device)
    scale_b = torch.tensor(1.0, device=x.device)
    out = torch._scaled_mm(
        x,
        w.T,
        scale_a=scale_a,
        scale_b=scale_b,
        out_dtype=torch.bfloat16,
    )
    return out if not isinstance(out, tuple) else out[0]


def sota_forward(x: torch.Tensor, w: torch.Tensor) -> torch.Tensor:
    """Best-available FP8 GEMM reference. x: (M, K) fp8, w: (N, K) fp8."""
    out = _try_flashinfer(x, w)
    if out is not None:
    

... (223 more chars)
assistant
shell
args
{
  "command": "<798 chars \u2014 see below>",
  "workingDirectory": "",
  "timeout": 30000,
  "toolCallId": "tool_dbf7c147-9b20-4b66-b23e-064cec484ec",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": false,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
   

... (2269 more chars)
command (798 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch
print('torch', torch.__version__)
print('cuda', torch.version.cuda)
print('device', torch.cuda.get_device_name(0))
print('capability', torch.cuda.get_device_capability(0))
print('fp8', hasattr(torch, 'float8_e4m3fn'))
# test triton
try:
    import triton
    print('triton', triton.__version__)
except: pass
# test scaled_mm
x = torch.randn(128,128, device='cuda', dtype=torch.bfloat16).to(torch.float8_e4m3fn)
w = torch.randn(128,128, device='cuda', dtype=torch.bfloat16).to(torch.float8_e4m3fn)
try:
    out = torch._scaled_mm(x, w.T, scale_a=torch.ones(1,device='cuda'), scale_b=torch.ones(1,device='cuda'), out_dtype=torch.bfloat16)
    print('scaled_mm works', out.shape)
except Exception as e:
    print('scaled_mm', e)
"
tool
stdout (4 chars)
null
assistant
I'll probe Triton FP8 dot and CUDA FP8 MMA support on this GPU, then inspect any existing reference kernels in the repo.
assistant
shell
args
{
  "command": "<1886 chars \u2014 see below>",
  "workingDirectory": "",
  "timeout": 60000,
  "toolCallId": "tool_6c9e5422-13d2-4c15-b013-80ae54f4aee",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": false,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
  

... (4481 more chars)
command (1886 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch
import triton
import triton.language as tl

# Test triton fp8 dot
code = '''
import triton
import triton.language as tl
import torch

@triton.jit
def test_dot(A, B, C, M, N, K, stride_am, stride_ak, stride_bk, stride_bn, stride_cm, stride_cn, BLOCK_M: tl.constexpr, BLOCK_N: tl.constexpr, BLOCK_K: tl.constexpr):
    pid_m = tl.program_id(0)
    pid_n = tl.program_id(1)
    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
    offs_k = tl.arange(0, BLOCK_K)
    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
    for k in range(0, K, BLOCK_K):
        a = tl.load(a_ptrs, mask=(offs_m[:, None] < M) & (offs_k[None, :] + k < K), other=0.0)
        b = tl.load(b_ptrs, mask=(offs_k[:, None] + k < K) & (offs_n[None, :] < N), other=0.0)
        acc = tl.dot(a, b, acc)
        a_ptrs += BLOCK_K * stride_ak
        b_ptrs += BLOCK_K * stride_bk
    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
    tl.store(c_ptrs, acc, mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))

M, N, K = 128, 128, 128
a = torch.randn(M, K, device='cuda', dtype=torch.bfloat16).to(torch.float8_e4m3fn)
b = torch.randn(N, K, device='cuda', dtype=torch.bfloat16).to(torch.float8_e4m3fn)
c = torch.zeros(M, N, device='cuda', dtype=torch.float32)
grid = lambda META: (triton.cdiv(M, META['BLOCK_M']), triton.cdiv(N, META['BLOCK_N']))
test_dot[grid](a, b, c, M, N, K, a.stride(0), a.stride(1), b.stride(1), b.stride(0), c.stride(0), c.stride(1), BLOCK_M=64, BLOCK_N=64, BLOCK_K=128)
ref = (a.float() @ b.float().T)
print('max diff', (c - ref).abs().max().item())
print('triton fp8 dot works!')
'

exec(code)
"
assistant
semSearch
args
{
  "query": "FP8 e4m3 GEMM kernel implementation SM120 Blackwell",
  "targetDirectories": [],
  "explanation": ""
}
tool
stderr (178 chars)
errorMessage: 'Codebase search is unavailable for this conversation because the codebase index could not be found. Do not retry SemanticSearch. Use Grep, Glob, and Read instead.'
tool
stderr (104 chars)
error: 'Glob pattern "**/*" matches every file and is not allowed. Use a more specific glob or no glob.'
tool
stdout (2553 chars) — TRUNCATED
failure:
  command:
    cd /workspace/problems/01_fp8_gemm && uv run python -c "
    import torch
    import triton
    import triton.language as tl
    
    # Test triton fp8 dot
    code = '''
    import triton
    import triton.language as tl
    import torch
    
    @triton.jit
    def test_dot(A, B, C, M, N, K, stride_am, stride_ak, stride_bk, stride_bn, stride_cm, stride_cn, BLOCK_M: tl.constexpr, BLOCK_N: tl.constexpr, BLOCK_K: tl.constexpr):
        pid_m = tl.program_id(0)
        pid_n = tl.program_id(1)
        offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
        offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
        offs_k = tl.arange(0, BLOCK_K)
        a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
        b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
        acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
        for k in range(0, K, BLOCK_K):
            a = tl.load(a_ptrs, mask=(offs_m[:, None] < M) & (offs_k[None, :] + k < K), other=0.0)
            b = tl.load(b_ptrs, mask=(offs_k[:, None] + k < K) & (offs_n[None, :] < N), other=0.0)
            acc = tl.dot(a, b, acc)
            a_ptrs += BLOCK_K * stride_ak
            b_ptrs += BLOCK_K * stride_bk
        c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
        tl.store(c_ptrs, acc, mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
    
    M, N, K = 128, 128, 128
    a = torch.randn(M, K, device='cuda', dtype=torch.bfl

... (1053 more chars)
assistant
edit /workspace/problems/01_fp8_gemm/test_triton_fp8.py
diff (59 lines)
--- /dev/null
+++ b//workspace/problems/01_fp8_gemm/test_triton_fp8.py
@@ -0,0 +1,56 @@
+import torch
+import triton
+import triton.language as tl
+
+
+@triton.jit
+def test_dot(
+    A, B, C,
+    M, N, K,
+    stride_am, stride_ak,
+    stride_bk, stride_bn,
+    stride_cm, stride_cn,
+    BLOCK_M: tl.constexpr, BLOCK_N: tl.constexpr, BLOCK_K: tl.constexpr,
+):
+    pid_m = tl.program_id(0)
+    pid_n = tl.program_id(1)
+    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
+    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
+    offs_k = tl.arange(0, BLOCK_K)
+    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
+    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
+    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
+    for k in range(0, K, BLOCK_K):
+        a = tl.load(
+            a_ptrs,
+            mask=(offs_m[:, None] < M) & (offs_k[None, :] + k < K),
+            other=0.0,
+        )
+        b = tl.load(
+            b_ptrs,
+            mask=(offs_k[:, None] + k < K) & (offs_n[None, :] < N),
+            other=0.0,
+        )
+        acc = tl.dot(a, b, acc)
+        a_ptrs += BLOCK_K * stride_ak
+        b_ptrs += BLOCK_K * stride_bk
+    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
+    tl.store(c_ptrs, acc, mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
+
+
+M, N, K = 128, 128, 128
+a = torch.randn(M, K, device="cuda", dtype=torch.bfloat16).to(torch.float8_e4m3fn)
+b = torch.randn(N, K, device="cuda", dtype=torch.bfloat16).to(torch.float8_e4m3fn)
+c = torch.zeros(M, N, device="cuda", dtype=torch.float32)
+grid = lambda META: (triton.cdiv(M, META["BLOCK_M"]), triton.cdiv(N, META["BLOCK_N"]))
+test_dot[grid](
+    a, b, c,
+    M, N, K,
+    a.stride(0), a.stride(1),
+    b.stride(1), b.stride(0),
+    c.stride(0), c.stride(1),
+    BLOCK_M=64, BLOCK_N=64, BLOCK_K=128,
+)
+ref = a.float() @ b.float().T
+print("max diff", (c - ref).abs().max().item())
+print("triton fp8 dot works!")
args
{
  "path": "/workspace/problems/01_fp8_gemm/test_triton_fp8.py",
  "streamContent": "<1871 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python test_triton_fp8.py 2>&1",
  "workingDirectory": "",
  "timeout": 120000,
  "toolCallId": "tool_6a1fd41b-78a0-437b-8bfb-b186d2a54cd",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_g

... (919 more chars)
assistant
grep /workspace
args
{
  "pattern": "fp8|e4m3|float8",
  "path": "/workspace",
  "glob": "**/*.py",
  "caseInsensitive": false,
  "headLimit": 40,
  "multiline": false,
  "toolCallId": "tool_90d9be14-687e-45f5-ba65-5ac096bd2f5",
  "offset": 0
}
tool
stdout (4 chars)
null
tool
stdout (4 chars)
null
assistant
Triton FP8 dot works. I'll implement a full GEMM kernel with per-channel scaling and verify correctness.
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (142 lines)
--- /dev/null
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -0,0 +1,139 @@
+"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
+import torch
+import torch.nn as nn
+import triton
+import triton.language as tl
+
+E4M3_MAX = 448.0
+
+
+@triton.jit
+def _fp8_gemm_kernel(
+    A,
+    B,
+    C,
+    Scales,
+    M,
+    N,
+    K,
+    stride_am,
+    stride_ak,
+    stride_bk,
+    stride_bn,
+    stride_cm,
+    stride_cn,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    GROUP_M: tl.constexpr,
+):
+    pid = tl.program_id(0)
+    num_pid_m = tl.cdiv(M, BLOCK_M)
+    num_pid_n = tl.cdiv(N, BLOCK_N)
+    num_pid_in_group = GROUP_M * num_pid_n
+    group_id = pid // num_pid_in_group
+    first_pid_m = group_id * GROUP_M
+    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
+    pid_m = first_pid_m + (pid % group_size_m)
+    pid_n = (pid % num_pid_in_group) // group_size_m
+
+    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
+    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
+    offs_k = tl.arange(0, BLOCK_K)
+
+    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
+    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
+
+    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
+    for k in range(0, K, BLOCK_K):
+        k_mask = offs_k[None, :] + k < K
+        a = tl.load(
+            a_ptrs,
+            mask=(offs_m[:, None] < M) & k_mask,
+            other=0.0,
+        )
+        b = tl.load(
+            b_ptrs,
+            mask=k_mask[:, None] & (offs_n[None, :] < N),
+            other=0.0,
+        )
+        acc = tl.dot(a, b, acc)
+        a_ptrs += BLOCK_K * stride_ak
+        b_ptrs += BLOCK_K * stride_bk
+
+    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
+    acc = acc * scales[None, :]
+
+    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
+    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
+
+
+def _fp8_gemm(x: torch.Tensor, weight: torch.Tensor, weight_scale: torch.Tensor) -> torch.Tensor:
+    """x: (M,K) fp8, weight: (N,K) fp8, weight_scale: (N,) fp32 -> (M,N) bf16."""
+    M, K = x.shape
+    N, K_w = weight.shape
+    assert K == K_w
+    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
+
+    # Heuristic tile sizes tuned for SM120 FP8 tensor cores.
+    if M <= 64:
+        block_m, block_n, block_k, group_m, num_warps, num_stages = 16, 128, 128, 8, 4, 3
+    elif N >= 8192:
+        block_m, block_n, block_k, group_m, num_warps, num_stages = 128, 256, 128, 8, 8, 3
+    else:
+        block_m, block_n, block_k, group_m, num_warps, num_stages = 128, 128, 128, 8, 8, 3
+
+    grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
+    _fp8_gemm_kernel[grid](
+        x,
+        weight,
+        y,
+        weight_scale,
+        M,
+        N,
+        K,
+        x.stride(0),
+        x.stride(1),
+        weight.stride(1),
+        weight.stride(0),
+        y.stride(0),
+        y.stride(1),
+        BLOCK_M=block_m,
+        BLOCK_N=block_n,
+        BLOCK_K=block_k,
+        GROUP_M=group_m,
+        num_warps=num_warps,
+        num_stages=num_stages,
+    )
+    return y
+
+
+class Model(nn.Module):
+    """y = ((x @ w.T) * weight_scale).to(bf16)."""
+
+    def __init__(self, M: int, N: int, K: int):
+        super().__init__()
+        self.M, self.N, self.K = M, N, K
+        w = torch.empty(N, K, dtype=torch.bfloat16)
+        nn.init.normal_(w, std=0.02)
+        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
+        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
+        self.register_buffer("weight", w_fp8)
+        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        return _fp8_gemm(x, self.weight, self.weight_scale)
+
+
+M = 4096
+N = 4096
+K = 4096
+
+
+def get_inputs():
+    x = (torch.rand(M, K) * 8 - 4).to(torch.float8_e4m3fn)
+    return [x]
+
+
+def get_init_inputs():
+    return [M, N, K]
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<3923 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_e4d8e629-b2e4-4ad8-9248-99007c09306",
  "simpleCommands": [
    "cd",
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  ],
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  "hasOutputRedirect": true,
  "parsingResult": {
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    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
     

... (899 more chars)
tool
stdout (7305 chars) — TRUNCATED
failure:
  command: 'cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1'
  workingDirectory: ''
  exitCode: 1
  signal: ''
  stdout:
    Traceback (most recent call last):
      File "/workspace/.venv/lib/python3.11/site-packages/triton/language/core.py", line 43, in wrapper
        return fn(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/triton/language/core.py", line 2035, in dot
        assert len(a_shape) == len(b_shape) >= 2, "input and other must have equal ranks >= 2"
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    AssertionError: input and other must have equal ranks >= 2
    
    The above exception was the direct cause of the following exception:
    
    Traceback (most recent call last):
      File "/workspace/problems/01_fp8_gemm/check.py", line 119, in <module>
        main()
      File "/workspace/problems/01_fp8_gemm/check.py", line 80, in main
        sol_out = sol_model(*inputs)
                  ^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/torch/nn/modules/module.py", line 1779, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/torch/nn/modules/module.py", line 1790, in _call_impl
        return forward_call(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/problems/01_fp8_gemm/solution

... (5805 more chars)
assistant
The kernel failed to compile with larger block sizes. I'll simplify the tile configuration and retest.
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (66 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -25,18 +25,9 @@
     BLOCK_M: tl.constexpr,
     BLOCK_N: tl.constexpr,
     BLOCK_K: tl.constexpr,
-    GROUP_M: tl.constexpr,
 ):
-    pid = tl.program_id(0)
-    num_pid_m = tl.cdiv(M, BLOCK_M)
-    num_pid_n = tl.cdiv(N, BLOCK_N)
-    num_pid_in_group = GROUP_M * num_pid_n
-    group_id = pid // num_pid_in_group
-    first_pid_m = group_id * GROUP_M
-    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
-    pid_m = first_pid_m + (pid % group_size_m)
-    pid_n = (pid % num_pid_in_group) // group_size_m
-
+    pid_m = tl.program_id(0)
+    pid_n = tl.program_id(1)
     offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
     offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
     offs_k = tl.arange(0, BLOCK_K)
@@ -69,21 +60,19 @@
 
 
 def _fp8_gemm(x: torch.Tensor, weight: torch.Tensor, weight_scale: torch.Tensor) -> torch.Tensor:
-    """x: (M,K) fp8, weight: (N,K) fp8, weight_scale: (N,) fp32 -> (M,N) bf16."""
     M, K = x.shape
     N, K_w = weight.shape
     assert K == K_w
     y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
 
-    # Heuristic tile sizes tuned for SM120 FP8 tensor cores.
     if M <= 64:
-        block_m, block_n, block_k, group_m, num_warps, num_stages = 16, 128, 128, 8, 4, 3
+        block_m, block_n, block_k, num_warps, num_stages = 32, 128, 128, 4, 3
     elif N >= 8192:
-        block_m, block_n, block_k, group_m, num_warps, num_stages = 128, 256, 128, 8, 8, 3
+        block_m, block_n, block_k, num_warps, num_stages = 64, 256, 128, 8, 4
     else:
-        block_m, block_n, block_k, group_m, num_warps, num_stages = 128, 128, 128, 8, 8, 3
+        block_m, block_n, block_k, num_warps, num_stages = 64, 64, 128, 4, 3
 
-    grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
+    grid = (triton.cdiv(M, block_m), triton.cdiv(N, block_n))
     _fp8_gemm_kernel[grid](
         x,
         weight,
@@ -101,7 +90,6 @@
         BLOCK_M=block_m,
         BLOCK_N=block_n,
         BLOCK_K=block_k,
-        GROUP_M=group_m,
         num_warps=num_warps,
         num_stages=num_stages,
     )
@@ -109,8 +97,6 @@
 
 
 class Model(nn.Module):
-    """y = ((x @ w.T) * weight_scale).to(bf16)."""
-
     def __init__(self, M: int, N: int, K: int):
         super().__init__()
         self.M, self.N, self.K = M, N, K
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<3317 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_dc1151be-6221-45a3-ac1d-d6b4b6d7f17",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
     

... (893 more chars)
tool
stdout (6253 chars) — TRUNCATED
failure:
  command: 'cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1'
  workingDirectory: ''
  exitCode: 1
  signal: ''
  stdout:
    Traceback (most recent call last):
      File "/workspace/problems/01_fp8_gemm/check.py", line 119, in <module>
        main()
      File "/workspace/problems/01_fp8_gemm/check.py", line 80, in main
        sol_out = sol_model(*inputs)
                  ^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/torch/nn/modules/module.py", line 1779, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/torch/nn/modules/module.py", line 1790, in _call_impl
        return forward_call(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/problems/01_fp8_gemm/solution.py", line 111, in forward
        return _fp8_gemm(x, self.weight, self.weight_scale)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/problems/01_fp8_gemm/solution.py", line 76, in _fp8_gemm
        _fp8_gemm_kernel[grid](
      File "/workspace/.venv/lib/python3.11/site-packages/triton/runtime/jit.py", line 370, in <lambda>
        return lambda *args, **kwargs: self.run(grid=grid, warmup=False, *args, **kwargs)
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/trit

... (4753 more chars)
assistant
The mask shapes were wrong — I'll fix them to match the working test pattern.
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (131 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,125 +1,12 @@
-"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
-import torch
-import torch.nn as nn
-import triton
-import triton.language as tl
-
-E4M3_MAX = 448.0
-
-
-@triton.jit
-def _fp8_gemm_kernel(
-    A,
-    B,
-    C,
-    Scales,
-    M,
-    N,
-    K,
-    stride_am,
-    stride_ak,
-    stride_bk,
-    stride_bn,
-    stride_cm,
-    stride_cn,
-    BLOCK_M: tl.constexpr,
-    BLOCK_N: tl.constexpr,
-    BLOCK_K: tl.constexpr,
-):
-    pid_m = tl.program_id(0)
-    pid_n = tl.program_id(1)
-    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
-    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
-    offs_k = tl.arange(0, BLOCK_K)
-
-    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
-    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
-
-    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
     for k in range(0, K, BLOCK_K):
-        k_mask = offs_k[None, :] + k < K
+        k_mask = offs_k + k < K
         a = tl.load(
             a_ptrs,
-            mask=(offs_m[:, None] < M) & k_mask,
+            mask=(offs_m[:, None] < M) & (k_mask[None, :]),
             other=0.0,
         )
         b = tl.load(
             b_ptrs,
-            mask=k_mask[:, None] & (offs_n[None, :] < N),
+            mask=(k_mask[:, None]) & (offs_n[None, :] < N),
             other=0.0,
-        )
-        acc = tl.dot(a, b, acc)
-        a_ptrs += BLOCK_K * stride_ak
-        b_ptrs += BLOCK_K * stride_bk
-
-    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
-    acc = acc * scales[None, :]
-
-    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
-    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
-
-
-def _fp8_gemm(x: torch.Tensor, weight: torch.Tensor, weight_scale: torch.Tensor) -> torch.Tensor:
-    M, K = x.shape
-    N, K_w = weight.shape
-    assert K == K_w
-    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
-
-    if M <= 64:
-        block_m, block_n, block_k, num_warps, num_stages = 32, 128, 128, 4, 3
-    elif N >= 8192:
-        block_m, block_n, block_k, num_warps, num_stages = 64, 256, 128, 8, 4
-    else:
-        block_m, block_n, block_k, num_warps, num_stages = 64, 64, 128, 4, 3
-
-    grid = (triton.cdiv(M, block_m), triton.cdiv(N, block_n))
-    _fp8_gemm_kernel[grid](
-        x,
-        weight,
-        y,
-        weight_scale,
-        M,
-        N,
-        K,
-        x.stride(0),
-        x.stride(1),
-        weight.stride(1),
-        weight.stride(0),
-        y.stride(0),
-        y.stride(1),
-        BLOCK_M=block_m,
-        BLOCK_N=block_n,
-        BLOCK_K=block_k,
-        num_warps=num_warps,
-        num_stages=num_stages,
-    )
-    return y
-
-
-class Model(nn.Module):
-    def __init__(self, M: int, N: int, K: int):
-        super().__init__()
-        self.M, self.N, self.K = M, N, K
-        w = torch.empty(N, K, dtype=torch.bfloat16)
-        nn.init.normal_(w, std=0.02)
-        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
-        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
-        self.register_buffer("weight", w_fp8)
-        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
-
-    def forward(self, x: torch.Tensor) -> torch.Tensor:
-        return _fp8_gemm(x, self.weight, self.weight_scale)
-
-
-M = 4096
-N = 4096
-K = 4096
-
-
-def get_inputs():
-    x = (torch.rand(M, K) * 8 - 4).to(torch.float8_e4m3fn)
-    return [x]
-
-
-def get_init_inputs():
-    return [M, N, K]
+        )
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<334 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_c0250ace-4abf-4d78-bbbe-0df2a1d9277",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
     

... (902 more chars)
tool
stdout (4651 chars) — TRUNCATED
failure:
  command: 'cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1'
  workingDirectory: ''
  exitCode: 1
  signal: ''
  stdout:
    Traceback (most recent call last):
      File "/workspace/problems/01_fp8_gemm/check.py", line 119, in <module>
        main()
      File "/workspace/problems/01_fp8_gemm/check.py", line 80, in main
        sol_out = sol_model(*inputs)
                  ^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/torch/nn/modules/module.py", line 1779, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/torch/nn/modules/module.py", line 1790, in _call_impl
        return forward_call(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/problems/01_fp8_gemm/solution.py", line 111, in forward
        return _fp8_gemm(x, self.weight, self.weight_scale)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/problems/01_fp8_gemm/solution.py", line 76, in _fp8_gemm
        _fp8_gemm_kernel[grid](
      File "/workspace/.venv/lib/python3.11/site-packages/triton/runtime/jit.py", line 370, in <lambda>
        return lambda *args, **kwargs: self.run(grid=grid, warmup=False, *args, **kwargs)
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/workspace/.venv/lib/python3.11/site-packages/trit

... (3151 more chars)
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (19 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,12 +1,6 @@
-    for k in range(0, K, BLOCK_K):
-        k_mask = offs_k + k < K
-        a = tl.load(
-            a_ptrs,
-            mask=(offs_m[:, None] < M) & (k_mask[None, :]),
-            other=0.0,
-        )
-        b = tl.load(
-            b_ptrs,
-            mask=(k_mask[:, None]) & (offs_n[None, :] < N),
-            other=0.0,
-        )+    if M <= 64:
+        block_m, block_n, block_k, num_warps, num_stages = 32, 128, 128, 4, 2
+    elif N >= 8192:
+        block_m, block_n, block_k, num_warps, num_stages = 64, 128, 128, 8, 2
+    else:
+        block_m, block_n, block_k, num_warps, num_stages = 64, 64, 128, 4, 3
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<278 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_a1c42ccd-2de5-42b4-822e-e871ce4e1d7",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
     

... (908 more chars)
tool
stdout (4 chars)
null
assistant
Correctness passes. Next I'll benchmark and tune tile sizes and kernel config for throughput.
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python benchmark.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_5a324d0d-0d9c-4786-bedc-e1d77a5a1c5",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
 

... (903 more chars)
assistant
read /workspace/src/hardware/rtx_pro_6000.py
args
{
  "path": "/workspace/src/hardware/rtx_pro_6000.py"
}
tool
stdout (1420 chars)
"""RTX PRO 6000 Blackwell Workstation — SM120, consumer-lineage Blackwell.

Peak tensor-core throughputs are dense-matrix advertised peaks. Actual kernels
will see 60-85% of peak on well-tuned code.
"""
from dataclasses import dataclass


@dataclass(frozen=True)
class HardwareTarget:
    name: str
    sm: str
    vram_gb: int
    peak_bandwidth_gb_s: float  # DRAM
    peak_tflops_dense: dict[str, float]  # dtype -> TFLOPS


RTX_PRO_6000 = HardwareTarget(
    name="RTX PRO 6000 Blackwell Workstation",
    sm="sm_120a",
    vram_gb=96,
    peak_bandwidth_gb_s=1800.0,
    peak_tflops_dense={
        # Blackwell GB202 dense tensor peaks. Derived from NVIDIA's headline
        # 4000 fp4-sparse AI TOPS -> fp4 dense 2000 -> fp8 1000 -> bf16 500
        # (each precision step = 2x; sparse = 2x dense). Verified empirically:
        # cuBLAS hits fp8 773 / bf16 412 TFLOPS on 4096^3 (~77-82% of these,
        # normal cuBLAS efficiency). The prior table was ~2.5x too low, which
        # produced peak_fraction > 1.0 for real fp8 kernels. fp32 is the 125
        # TFLOPS SIMT figure from the spec sheet.
        "fp4": 2000.0,
        "nvfp4": 2000.0,
        "mxfp4": 2000.0,
        "fp6": 1000.0,
        "fp8": 1000.0,
        "bf16": 500.0,
        "fp16": 500.0,
        "tf32": 250.0,
        "fp32": 125.0,  # non-tensor-core SIMT fp32 (spec sheet)
        "int8": 1000.0,
        "int4": 2000.0,
    },
)
tool
stdout (4 chars)
null
assistant
Shape 1 (K=4127) is far too slow — I'll dig into that regression and tune tile sizes for the other shapes.
assistant
read /workspace/src/eval/timing.py
args
{
  "path": "/workspace/src/eval/timing.py"
}
tool
stdout (4314 chars) — TRUNCATED
"""Centralized GPU timing for benchmark.py files.

All problems' benchmark.py should call `time_fn` from here so we have one
implementation of warmup, L2 flush, and CUDA event capture to maintain.

Methodology:
  - 10 warmup calls absorb Triton autotune (typical ~7 configs) and
    torch.compile reduce-overhead CUDA-graph capture.
  - Between each timed call, `_l2_flush()` writes 128 MB to evict L2
    (Blackwell L2 is 96 MB; we want any prior L2 contents flushed so
    we measure HBM-load bandwidth, not L2-cached bandwidth).
  - GPU timing via cuda.Event with synchronize() AFTER record() but
    BEFORE elapsed_time() — the canonical NVIDIA pattern.
  - Reported value is the median of `iters` trials, robust to outliers.

Notes / known biases not addressed here:
  - torch.compile(mode="reduce-overhead") gets CUDA graphs which eliminate
    launch overhead. Custom Triton/CUDA kernels do NOT get this treatment.
    On small shapes where launch overhead matters, this gives compile an
    artificial advantage. We accept this as the cost of using the agreed
    "compiled" baseline policy.
  - cuBLAS / cuDNN allocate workspaces on first call. 10 warmup absorbs.
  - Median over a fairly small number of trials (default 30) is fine for
    headline numbers but won't catch bimodal distributions. Use --extra
    instrumentation if you ever care.
"""
from __future__ import annotations

import os
import re
import statistics
import time
from datetime import UTC, datetime

import torch

# Bl

... (2814 more chars)
assistant
shell
args
{
  "command": "<936 chars \u2014 see below>",
  "workingDirectory": "",
  "timeout": 120000,
  "toolCallId": "tool_e9dad82b-2bca-435e-8f7c-da53026850b",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
   

... (2740 more chars)
command (936 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch, time
import reference, solution

device = 'cuda'
for shape in [{'M':4096,'N':4096,'K':4096}, {'M':4096,'N':4096,'K':4127}]:
    reference.M = shape['M']; reference.N = shape['N']; reference.K = shape['K']
    ref_model = reference.Model(*reference.get_init_inputs()).to(device).eval()
    sol_model = solution.Model(*reference.get_init_inputs()).to(device).eval()
    sol_model.load_state_dict(ref_model.state_dict())
    torch.manual_seed(2026)
    x = reference.get_inputs()[0].to(device)
    
    # warmup
    for _ in range(5):
        sol_model(x)
    torch.cuda.synchronize()
    
    times = []
    for _ in range(30):
        t0 = time.perf_counter()
        sol_model(x)
        torch.cuda.synchronize()
        times.append((time.perf_counter()-t0)*1000)
    import statistics
    print(shape, 'median', statistics.median(times), 'min', min(times))
" 2>&1
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "<1689 chars \u2014 see below>",
  "workingDirectory": "",
  "timeout": 120000,
  "toolCallId": "tool_3756ce47-8f03-41ea-a6db-ca8624a3393",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
  

... (4303 more chars)
command (1689 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch, time, statistics
import reference, solution

device = 'cuda'
shape = {'M':4096,'N':4096,'K':4127}
reference.M = shape['M']; reference.N = shape['N']; reference.K = shape['K']
ref_model = reference.Model(*reference.get_init_inputs()).to(device).eval()
sol_model = solution.Model(*reference.get_init_inputs()).to(device).eval()
sol_model.load_state_dict(ref_model.state_dict())
torch.manual_seed(2026)
x = reference.get_inputs()[0].to(device)

# scaled_mm baseline (not for solution, just perf reference)
scale = torch.tensor(1.0, device=device)
w = ref_model.weight

for _ in range(10):
    torch._scaled_mm(x, w.T, scale_a=scale, scale_b=scale, out_dtype=torch.bfloat16)
torch.cuda.synchronize()

times=[]
for _ in range(30):
    t0=time.perf_counter()
    torch._scaled_mm(x, w.T, scale_a=scale, scale_b=scale, out_dtype=torch.bfloat16)
    torch.cuda.synchronize()
    times.append((time.perf_counter()-t0)*1000)
print('scaled_mm ms', statistics.median(times))

for _ in range(10):
    sol_model(x)
torch.cuda.synchronize()
times=[]
for _ in range(30):
    t0=time.perf_counter()
    sol_model(x)
    torch.cuda.synchronize()
    times.append((time.perf_counter()-t0)*1000)
print('solution ms', statistics.median(times))

# direct kernel
from solution import _fp8_gemm
for _ in range(10):
    _fp8_gemm(x, ref_model.weight, ref_model.weight_scale)
torch.cuda.synchronize()
times=[]
for _ in range(30):
    t0=time.perf_counter()
    _fp8_gemm(x, ref_model.weight, ref_model.weight_scale)
    torch.cuda.synchronize()
    times.append((time.perf_counter()-t0)*1000)
print('kernel ms', statistics.median(times))
" 2>&1
assistant
grep /workspace/.venv/lib/python3.11/site-packages/triton
args
{
  "pattern": "autotune|fp8.*gemm|float8",
  "path": "/workspace/.venv/lib/python3.11/site-packages/triton",
  "glob": "**/*.py",
  "caseInsensitive": false,
  "headLimit": 30,
  "multiline": false,
  "toolCallId": "tool_f833f9c9-0150-4556-952a-fa4a97d4acf",
  "offset": 0
}
tool
stdout (4 chars)
null
tool
stdout (2487 chars) — TRUNCATED
failure:
  command:
    cd /workspace/problems/01_fp8_gemm && uv run python -c "
    import torch, time, statistics
    import reference, solution
    
    device = 'cuda'
    shape = {'M':4096,'N':4096,'K':4127}
    reference.M = shape['M']; reference.N = shape['N']; reference.K = shape['K']
    ref_model = reference.Model(*reference.get_init_inputs()).to(device).eval()
    sol_model = solution.Model(*reference.get_init_inputs()).to(device).eval()
    sol_model.load_state_dict(ref_model.state_dict())
    torch.manual_seed(2026)
    x = reference.get_inputs()[0].to(device)
    
    # scaled_mm baseline (not for solution, just perf reference)
    scale = torch.tensor(1.0, device=device)
    w = ref_model.weight
    
    for _ in range(10):
        torch._scaled_mm(x, w.T, scale_a=scale, scale_b=scale, out_dtype=torch.bfloat16)
    torch.cuda.synchronize()
    
    times=[]
    for _ in range(30):
        t0=time.perf_counter()
        torch._scaled_mm(x, w.T, scale_a=scale, scale_b=scale, out_dtype=torch.bfloat16)
        torch.cuda.synchronize()
        times.append((time.perf_counter()-t0)*1000)
    print('scaled_mm ms', statistics.median(times))
    
    for _ in range(10):
        sol_model(x)
    torch.cuda.synchronize()
    times=[]
    for _ in range(30):
        t0=time.perf_counter()
        sol_model(x)
        torch.cuda.synchronize()
        times.append((time.perf_counter()-t0)*1000)
    print('solution ms', statistics.median(times))
    
    # direct kernel
    f

... (987 more chars)
assistant
shell
args
{
  "command": "<774 chars \u2014 see below>",
  "workingDirectory": "",
  "timeout": 120000,
  "toolCallId": "tool_a2c3a3fb-b32e-4f56-9b16-5a5c2a7c11a",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
   

... (2406 more chars)
command (774 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch, time, statistics
from solution import _fp8_gemm
import reference

device='cuda'
M,N=4096,4096
reference.M=M; reference.N=N
for K in [4096, 4100, 4112, 4127, 4130, 4144, 4160]:
    reference.K=K
    ref = reference.Model(M,N,K).to(device).eval()
    x = (torch.rand(M,K,device=device)*8-4).to(torch.float8_e4m3fn)
    for _ in range(5):
        _fp8_gemm(x, ref.weight, ref.weight_scale)
    torch.cuda.synchronize()
    times=[]
    for _ in range(20):
        t0=time.perf_counter()
        _fp8_gemm(x, ref.weight, ref.weight_scale)
        torch.cuda.synchronize()
        times.append((time.perf_counter()-t0)*1000)
    print(f'K={K} iters={ (K+127)//128 } ms={statistics.median(times):.3f}')
" 2>&1
tool
stdout (4 chars)
null
assistant
The slowdown comes from K not being divisible by 128 — I'll split the kernel into a full-tile main loop and a masked epilogue.
assistant
read /workspace/problems/01_fp8_gemm/solution.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py"
}
tool
stdout (3321 chars) — TRUNCATED
"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
import torch
import torch.nn as nn
import triton
import triton.language as tl

E4M3_MAX = 448.0


@triton.jit
def _fp8_gemm_kernel(
    A,
    B,
    C,
    Scales,
    M,
    N,
    K,
    stride_am,
    stride_ak,
    stride_bk,
    stride_bn,
    stride_cm,
    stride_cn,
    BLOCK_M: tl.constexpr,
    BLOCK_N: tl.constexpr,
    BLOCK_K: tl.constexpr,
):
    pid_m = tl.program_id(0)
    pid_n = tl.program_id(1)
    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
    offs_k = tl.arange(0, BLOCK_K)

    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn

    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
    for k in range(0, K, BLOCK_K):
        k_mask = offs_k + k < K
        a = tl.load(
            a_ptrs,
            mask=(offs_m[:, None] < M) & (k_mask[None, :]),
            other=0.0,
        )
        b = tl.load(
            b_ptrs,
            mask=(k_mask[:, None]) & (offs_n[None, :] < N),
            other=0.0,
        )
        acc = tl.dot(a, b, acc)
        a_ptrs += BLOCK_K * stride_ak
        b_ptrs += BLOCK_K * stride_bk

    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
    acc = acc * scales[None, :]

    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
    tl.store(c_ptrs, acc.to(tl.bfloat16

... (1821 more chars)
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (236 lines — TRUNCATED)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,6 +1,230 @@
+"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
+import torch
+import torch.nn as nn
+import triton
+import triton.language as tl
+
+E4M3_MAX = 448.0
+
+
+@triton.autotune(
+    configs=[
+        triton.Config({"BLOCK_M": 128, "BLOCK_N": 128, "BLOCK_K": 128, "GROUP_M": 8}, num_stages=3, num_warps=8),
+        triton.Config({"BLOCK_M": 128, "BLOCK_N": 64, "BLOCK_K": 128, "GROUP_M": 8}, num_stages=3, num_warps=4),
+        triton.Config({"BLOCK_M": 64, "BLOCK_N": 128, "BLOCK_K": 128, "GROUP_M": 8}, num_stages=3, num_warps=4),
+        triton.Config({"BLOCK_M": 64, "BLOCK_N": 64, "BLOCK_K": 128, "GROUP_M": 8}, num_stages=3, num_warps=4),
+        triton.Config({"BLOCK_M": 128, "BLOCK_N": 256, "BLOCK_K": 128, "GROUP_M": 4}, num_stages=2, num_warps=8),
+    ],
+    key=["M", "N", "K", "HAS_TAIL"],
+)
+@triton.jit
+def _fp8_gemm_kernel(
+    A,
+    B,
+    C,
+    Scales,
+    M,
+    N,
+    K,
+    stride_am,
+    stride_ak,
+    stride_bk,
+    stride_bn,
+    stride_cm,
+    stride_cn,
+    HAS_TAIL: tl.constexpr,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    GROUP_M: tl.constexpr,
+):
+    pid = tl.program_id(0)
+    num_pid_m = tl.cdiv(M, BLOCK_M)
+    num_pid_n = tl.cdiv(N, BLOCK_N)
+    num_pid_in_group = GROUP_M * num_pid_n
+    group_id = pid // num_pid_in_group
+    first_pid_m = group_id * GROUP_M
+    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
+    pid_m = first_pid_m + (pid % group_size_m)
+    pid_n = (pid % num_pid_in_group) // group_size_m
+
+    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
+    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
+    offs_k = tl.arange(0, BLOCK_K)
+
+    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
+    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
+
+    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
+
+    full_k = (K // BLOCK_K) * BLOCK_K
+    for k in range(0, full_k, BLOCK_K):
+        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
+        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
+        acc = tl.dot(a, b, acc)
+        a_ptrs += BLOCK_K * stride_ak
+        b_ptrs += BLOCK_K * stride_bk
+
+    if HAS_TAIL:
+        k = full_k
+        k_mask = offs_k + k < K
+        a = tl.load(
+            a_ptrs,
+            mask=(offs_m[:, None] < M) & k_mask[None, :],
+            other=0.0,
+        )
+        b = tl.load(
+            b_ptrs,
+            mask=k_mask[:, None] & (offs_n[None, :] < N),
+            other=0.0,
+        )
+        acc = tl.dot(a, b, acc)
+
+    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
+    acc = acc * scales[None, :]
+
+    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
+    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
+
+
+@triton.autotune(
+    configs=[
+        triton.Config({"BLOCK_M": 16, "BLOCK_N": 128, "BLOCK_K": 128}, num_stages=2, num_warps=4),
+        triton.Config({"BLOCK_M": 32, "BLOCK_N": 128, "BLOCK_K": 128}, num_stages=2, num_warps=4),
+        triton.Config({"BLOCK_M": 32, "BLOCK_N": 256, "BLOCK_K": 128}, num_stages=2, num_warps=8),
+    ],
+    key=["N", "K", "HAS_TAIL"],
+)
+@triton.jit
+def _fp8_gemm_skinny_kernel(
+    A,
+    B,
+    C,
+    Scales,
+    M,
+    N,
+    K,
+    stride_am,
+    stride_ak,
+    stride_bk,
+    stride_bn,
+    stride_cm,
+    stride_cn,
+    HAS_TAIL: tl.constexpr,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+):
+    pid_n = tl.program_id(0)
+    offs_m = tl.arange(0, BLOCK_M)
+    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
+    offs_k = tl.arange(0, BLOCK_K)
+
+    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
+    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
+
+    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
+    full_k = (K // BLOCK_K) * BLOCK_K
+    for k in range(0, full_k, BLOCK_K):
+        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
+        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
+        acc = tl.dot(a, b, acc)
+        a_ptrs += BLOCK_K * stride_ak
+        b_ptrs += BLOCK_K * stride_bk
+
+    if HAS_TAIL:
+        k = full_k
+        k_mask = offs_k + k < K
+        a = tl.load(
+            a_ptrs,
+            mask=(offs_m[:, None] < M) & k_mask[None, :],
+            other=0.0,
+        )
+        b = tl.load(
+            b_ptrs,
+            mask=k_mask[:, None] & (offs_n[None, :] < N),
+            other=0.0,
+        )
+        acc = tl.dot(a, b, acc)
+
+    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
+    acc = acc * scales[None, :]
+
+    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
+    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
+
+
+def _fp8_gemm(x: torch.Tensor, weight: torch.Tensor, weight_scale: torch.Tensor) -> torch.Tensor:
+    M, K = x.shape
+    N, K_w = weight.shape
+    assert K == K_w
+    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
+    has_tail = (K % 128) != 0
+    block_k = 128
+
     if M <= 64:
-        block_m, block_n, block_k, num_warps, num_stages = 32, 128, 128, 4, 2
-    elif N >= 8192:
-        block_m, block_n, block_k, num_warps, num_stages = 64, 128, 128, 8, 2
+        grid = (triton.cdiv(N, 128),)
+        _fp8_gemm_skinny_kernel[grid](
+            x,
+            weight,
+            y,
+            weight_scale,
+            M,
+            N,
+            K,
+            x.stride(0),
+            x.stride(1),
+            weight.stride(1),
+            weight.stride(0),
+            y.stride(0),
+            y.stride(1),
+            HAS_TAIL=has_tail,
+        )
     else:
-        block_m, block

... (1308 more chars)
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<6704 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "<746 chars \u2014 see below>",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_950de24b-6691-43c6-93ca-817cc09bdf4",
  "simpleCommands": [
    "cd",
    "uv",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name":

... (2821 more chars)
command (746 chars)
cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python -c "
import torch, time, statistics
from solution import _fp8_gemm
import reference
device='cuda'
for K in [4096, 4127]:
    reference.M=4096; reference.N=4096; reference.K=K
    ref = reference.Model(4096,4096,K).to(device).eval()
    x = (torch.rand(4096,K,device=device)*8-4).to(torch.float8_e4m3fn)
    for _ in range(10): _fp8_gemm(x, ref.weight, ref.weight_scale)
    torch.cuda.synchronize()
    times=[]
    for _ in range(20):
        t0=time.perf_counter()
        _fp8_gemm(x, ref.weight, ref.weight_scale)
        torch.cuda.synchronize()
        times.append((time.perf_counter()-t0)*1000)
    print(f'K={K} ms={statistics.median(times):.3f}')
" 2>&1
tool
stdout (1410 chars)
failure:
  command:
    cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python -c "
    import torch, time, statistics
    from solution import _fp8_gemm
    import reference
    device='cuda'
    for K in [4096, 4127]:
        reference.M=4096; reference.N=4096; reference.K=K
        ref = reference.Model(4096,4096,K).to(device).eval()
        x = (torch.rand(4096,K,device=device)*8-4).to(torch.float8_e4m3fn)
        for _ in range(10): _fp8_gemm(x, ref.weight, ref.weight_scale)
        torch.cuda.synchronize()
        times=[]
        for _ in range(20):
            t0=time.perf_counter()
            _fp8_gemm(x, ref.weight, ref.weight_scale)
            torch.cuda.synchronize()
            times.append((time.perf_counter()-t0)*1000)
        print(f'K={K} ms={statistics.median(times):.3f}')
    " 2>&1
  workingDirectory: ''
  exitCode: 1
  signal: ''
  stdout:
    FAIL: shape 0 {'M': 4096, 'N': 4096, 'K': 4096} seed 42 case nominal: tolerance exceeded: max_abs_diff=12.3125 max_rel_diff=1 bad=30572/16777216 worst_idx=(4092, 3987) (atol=0.2, rtol=0.2)
  stderr: ''
  executionTime: 3931
  interleavedOutput:
    FAIL: shape 0 {'M': 4096, 'N': 4096, 'K': 4096} seed 42 case nominal: tolerance exceeded: max_abs_diff=12.3125 max_rel_diff=1 bad=30572/16777216 worst_idx=(4092, 3987) (atol=0.2, rtol=0.2)
  aborted: False
  localExecutionTimeMs: 3859
isBackground: False
assistant
Autotune likely picked an incorrect config — I'll switch to fixed, validated tile sizes.
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (90 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -7,16 +7,6 @@
 E4M3_MAX = 448.0
 
 
-@triton.autotune(
-    configs=[
-        triton.Config({"BLOCK_M": 128, "BLOCK_N": 128, "BLOCK_K": 128, "GROUP_M": 8}, num_stages=3, num_warps=8),
-        triton.Config({"BLOCK_M": 128, "BLOCK_N": 64, "BLOCK_K": 128, "GROUP_M": 8}, num_stages=3, num_warps=4),
-        triton.Config({"BLOCK_M": 64, "BLOCK_N": 128, "BLOCK_K": 128, "GROUP_M": 8}, num_stages=3, num_warps=4),
-        triton.Config({"BLOCK_M": 64, "BLOCK_N": 64, "BLOCK_K": 128, "GROUP_M": 8}, num_stages=3, num_warps=4),
-        triton.Config({"BLOCK_M": 128, "BLOCK_N": 256, "BLOCK_K": 128, "GROUP_M": 4}, num_stages=2, num_warps=8),
-    ],
-    key=["M", "N", "K", "HAS_TAIL"],
-)
 @triton.jit
 def _fp8_gemm_kernel(
     A,
@@ -87,14 +77,6 @@
     tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
 
 
-@triton.autotune(
-    configs=[
-        triton.Config({"BLOCK_M": 16, "BLOCK_N": 128, "BLOCK_K": 128}, num_stages=2, num_warps=4),
-        triton.Config({"BLOCK_M": 32, "BLOCK_N": 128, "BLOCK_K": 128}, num_stages=2, num_warps=4),
-        triton.Config({"BLOCK_M": 32, "BLOCK_N": 256, "BLOCK_K": 128}, num_stages=2, num_warps=8),
-    ],
-    key=["N", "K", "HAS_TAIL"],
-)
 @triton.jit
 def _fp8_gemm_skinny_kernel(
     A,
@@ -154,16 +136,24 @@
     tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
 
 
+def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
+    if M <= 64:
+        return 32, 128, 128, 4, 2, 1
+    if N >= 12000:
+        return 128, 256, 128, 8, 2, 4
+    return 128, 128, 128, 8, 3, 8
+
+
 def _fp8_gemm(x: torch.Tensor, weight: torch.Tensor, weight_scale: torch.Tensor) -> torch.Tensor:
     M, K = x.shape
     N, K_w = weight.shape
     assert K == K_w
     y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
     has_tail = (K % 128) != 0
-    block_k = 128
+    block_m, block_n, block_k, num_warps, num_stages, group_m = _pick_config(M, N)
 
     if M <= 64:
-        grid = (triton.cdiv(N, 128),)
+        grid = (triton.cdiv(N, block_n),)
         _fp8_gemm_skinny_kernel[grid](
             x,
             weight,
@@ -179,9 +169,14 @@
             y.stride(0),
             y.stride(1),
             HAS_TAIL=has_tail,
+            BLOCK_M=block_m,
+            BLOCK_N=block_n,
+            BLOCK_K=block_k,
+            num_warps=num_warps,
+            num_stages=num_stages,
         )
     else:
-        grid = (triton.cdiv(M, 128) * triton.cdiv(N, 128),)
+        grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
         _fp8_gemm_kernel[grid](
             x,
             weight,
@@ -197,6 +192,12 @@
             y.stride(0),
             y.stride(1),
             HAS_TAIL=has_tail,
+            BLOCK_M=block_m,
+            BLOCK_N=block_n,
+            BLOCK_K=block_k,
+            GROUP_M=group_m,
+            num_warps=num_warps,
+            num_stages=num_stages,
         )
     return y
 
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<6325 chars \u2014 see diff>"
}
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1",
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  "timeout": 300000,
  "toolCallId": "tool_618f51b1-4983-45bc-bd05-e5b2d6cb145",
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            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
     

... (908 more chars)
tool
stdout (4 chars)
null
tool
stdout (4 chars)
null
assistant
shell
args
{
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        "fullText": "cd /workspace/problems/01_fp8_gemm"
 

... (916 more chars)
assistant
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          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
   

... (2269 more chars)
command (715 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch, time, statistics
from solution import _fp8_gemm
import reference
device='cuda'
for K in [4096, 4127]:
    reference.M=4096; reference.N=4096; reference.K=K
    ref = reference.Model(4096,4096,K).to(device).eval()
    x = (torch.rand(4096,K,device=device)*8-4).to(torch.float8_e4m3fn)
    for _ in range(10): _fp8_gemm(x, ref.weight, ref.weight_scale)
    torch.cuda.synchronize()
    times=[]
    for _ in range(20):
        t0=time.perf_counter()
        _fp8_gemm(x, ref.weight, ref.weight_scale)
        torch.cuda.synchronize()
        times.append((time.perf_counter()-t0)*1000)
    print(f'K={K} ms={statistics.median(times):.3f}')
" 2>&1
tool
stdout (4 chars)
null
tool
stdout (4 chars)
null
assistant
Padding K to a multiple of 128 with zeros should let us use the fast no-tail kernel on K=4127.
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (218 lines — TRUNCATED)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,155 +1,16 @@
-"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
-import torch
-import torch.nn as nn
-import triton
-import triton.language as tl
-
-E4M3_MAX = 448.0
-
-
-@triton.jit
-def _fp8_gemm_kernel(
-    A,
-    B,
-    C,
-    Scales,
-    M,
-    N,
-    K,
-    stride_am,
-    stride_ak,
-    stride_bk,
-    stride_bn,
-    stride_cm,
-    stride_cn,
-    HAS_TAIL: tl.constexpr,
-    BLOCK_M: tl.constexpr,
-    BLOCK_N: tl.constexpr,
-    BLOCK_K: tl.constexpr,
-    GROUP_M: tl.constexpr,
-):
-    pid = tl.program_id(0)
-    num_pid_m = tl.cdiv(M, BLOCK_M)
-    num_pid_n = tl.cdiv(N, BLOCK_N)
-    num_pid_in_group = GROUP_M * num_pid_n
-    group_id = pid // num_pid_in_group
-    first_pid_m = group_id * GROUP_M
-    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
-    pid_m = first_pid_m + (pid % group_size_m)
-    pid_n = (pid % num_pid_in_group) // group_size_m
-
-    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
-    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
-    offs_k = tl.arange(0, BLOCK_K)
-
-    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
-    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
-
-    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
-
-    full_k = (K // BLOCK_K) * BLOCK_K
-    for k in range(0, full_k, BLOCK_K):
-        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
-        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
-        acc = tl.dot(a, b, acc)
-        a_ptrs += BLOCK_K * stride_ak
-        b_ptrs += BLOCK_K * stride_bk
-
-    if HAS_TAIL:
-        k = full_k
-        k_mask = offs_k + k < K
-        a = tl.load(
-            a_ptrs,
-            mask=(offs_m[:, None] < M) & k_mask[None, :],
-            other=0.0,
-        )
-        b = tl.load(
-            b_ptrs,
-            mask=k_mask[:, None] & (offs_n[None, :] < N),
-            other=0.0,
-        )
-        acc = tl.dot(a, b, acc)
-
-    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
-    acc = acc * scales[None, :]
-
-    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
-    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
-
-
-@triton.jit
-def _fp8_gemm_skinny_kernel(
-    A,
-    B,
-    C,
-    Scales,
-    M,
-    N,
-    K,
-    stride_am,
-    stride_ak,
-    stride_bk,
-    stride_bn,
-    stride_cm,
-    stride_cn,
-    HAS_TAIL: tl.constexpr,
-    BLOCK_M: tl.constexpr,
-    BLOCK_N: tl.constexpr,
-    BLOCK_K: tl.constexpr,
-):
-    pid_n = tl.program_id(0)
-    offs_m = tl.arange(0, BLOCK_M)
-    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
-    offs_k = tl.arange(0, BLOCK_K)
-
-    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
-    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
-
-    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
-    full_k = (K // BLOCK_K) * BLOCK_K
-    for k in range(0, full_k, BLOCK_K):
-        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
-        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
-        acc = tl.dot(a, b, acc)
-        a_ptrs += BLOCK_K * stride_ak
-        b_ptrs += BLOCK_K * stride_bk
-
-    if HAS_TAIL:
-        k = full_k
-        k_mask = offs_k + k < K
-        a = tl.load(
-            a_ptrs,
-            mask=(offs_m[:, None] < M) & k_mask[None, :],
-            other=0.0,
-        )
-        b = tl.load(
-            b_ptrs,
-            mask=k_mask[:, None] & (offs_n[None, :] < N),
-            other=0.0,
-        )
-        acc = tl.dot(a, b, acc)
-
-    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
-    acc = acc * scales[None, :]
-
-    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
-    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
-
-
-def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
-    if M <= 64:
-        return 32, 128, 128, 4, 2, 1
-    if N >= 12000:
-        return 128, 256, 128, 8, 2, 4
-    return 128, 128, 128, 8, 3, 8
-
-
 def _fp8_gemm(x: torch.Tensor, weight: torch.Tensor, weight_scale: torch.Tensor) -> torch.Tensor:
     M, K = x.shape
     N, K_w = weight.shape
     assert K == K_w
+
+    block_k = 128
+    pad_k = (block_k - (K % block_k)) % block_k
+    if pad_k:
+        x = torch.nn.functional.pad(x, (0, pad_k))
+        weight = torch.nn.functional.pad(weight, (0, pad_k))
+        K = K + pad_k
+
     y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
-    has_tail = (K % 128) != 0
     block_m, block_n, block_k, num_warps, num_stages, group_m = _pick_config(M, N)
 
     if M <= 64:
@@ -168,7 +29,7 @@
             weight.stride(0),
             y.stride(0),
             y.stride(1),
-            HAS_TAIL=has_tail,
+            HAS_TAIL=False,
             BLOCK_M=block_m,
             BLOCK_N=block_n,
             BLOCK_K=block_k,
@@ -191,7 +52,7 @@
             weight.stride(0),
             y.stride(0),
             y.stride(1),
-            HAS_TAIL=has_tail,
+            HAS_TAIL=False,
             BLOCK_M=block_m,
             BLOCK_N=block_n,
             BLOCK_K=block_k,
@@ -199,33 +60,4 @@
             num_warps=num_warps,
             num_stages=num_stages,
         )
-    return y
-
-
-class Model(nn.Module):
-    def __init__(self, M: int, N: int, K: int):
-        super().__init__()
-        self.M, self.N, self.K = M, N, K
-        w = torch.empty(N, K, dtype=torch.bfloat16)
-        nn.init.normal_(w, std=0.02)
-        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
-        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
-        self.register_buffer("weight", w_fp8)
-        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
-
-    def forwar

... (299 more chars)
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<1726 chars \u2014 see diff>"
}
assistant
shell
args
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            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText

... (1481 more chars)
tool
stdout (4 chars)
null
tool
stdout (4 chars)
null
assistant
K=4127 is fixed. Next I'll tune the skinny decode shape and push compute-bound cases toward higher TFLOPS.
assistant
shell
args
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        "fullText": "cd /workspa

... (943 more chars)
assistant
shell
args
{
  "command": "<1596 chars \u2014 see below>",
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        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
  

... (4072 more chars)
command (1596 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
# sweep skinny kernel configs
import torch, time, statistics
import triton
from solution import _fp8_gemm_skinny_kernel

M,N,K = 32, 8192, 8192
x = torch.randn(M,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
w = torch.randn(N,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
s = torch.ones(N, device='cuda', dtype=torch.float32)
y = torch.empty(M,N,device='cuda',dtype=torch.bfloat16)

configs = [
    (16,128,128,4,2),(32,128,128,4,2),(32,256,128,8,2),(16,256,128,8,2),
    (32,128,256,4,3),(32,64,128,2,2),(64,128,128,4,2)
]
for bm,bn,bk,nw,ns in configs:
    try:
        grid=(triton.cdiv(N,bn),)
        for _ in range(5):
            _fp8_gemm_skinny_kernel[grid](x,w,y,s,M,N,K,x.stride(0),x.stride(1),w.stride(1),w.stride(0),y.stride(0),y.stride(1),HAS_TAIL=False,BLOCK_M=bm,BLOCK_N=bn,BLOCK_K=bk,num_warps=nw,num_stages=ns)
        torch.cuda.synchronize()
        times=[]
        for _ in range(30):
            t0=time.perf_counter()
            _fp8_gemm_skinny_kernel[grid](x,w,y,s,M,N,K,x.stride(0),x.stride(1),w.stride(1),w.stride(0),y.stride(0),y.stride(1),HAS_TAIL=False,BLOCK_M=bm,BLOCK_N=bn,BLOCK_K=bk,num_warps=nw,num_stages=ns)
            torch.cuda.synchronize()
            times.append((time.perf_counter()-t0)*1000)
        flops=2*M*N*K/1e9
        ms=statistics.median(times)
        print(f'bm={bm} bn={bn} bk={bk} nw={nw} ns={ns} ms={ms:.3f} tflops={flops/ms*1e3:.1f} gbps={(M*K+N*K+M*N*2)/ms/1e6:.0f}')
    except Exception as e:
        print(f'bm={bm} bn={bn} FAIL {e}')
" 2>&1
tool
stdout (4 chars)
null
tool
stdout (4 chars)
null
assistant
shell
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{
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        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
  

... (4067 more chars)
command (1592 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch, time, statistics, triton
from solution import _fp8_gemm_kernel

M,N,K = 4096,4096,4096
x = torch.randn(M,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
w = torch.randn(N,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
s = torch.ones(N, device='cuda', dtype=torch.float32)
y = torch.empty(M,N,device='cuda',dtype=torch.bfloat16)

configs = [
    (128,128,128,8,3,8),(128,256,128,8,2,4),(64,128,128,4,3,8),(128,64,128,4,3,8),
    (256,128,128,8,2,4),(128,128,256,8,3,8),(64,64,128,4,3,8)
]
for bm,bn,bk,nw,ns,gm in configs:
    try:
        grid=(triton.cdiv(M,bm)*triton.cdiv(N,bn),)
        for _ in range(5):
            _fp8_gemm_kernel[grid](x,w,y,s,M,N,K,x.stride(0),x.stride(1),w.stride(1),w.stride(0),y.stride(0),y.stride(1),HAS_TAIL=False,BLOCK_M=bm,BLOCK_N=bn,BLOCK_K=bk,GROUP_M=gm,num_warps=nw,num_stages=ns)
        torch.cuda.synchronize()
        times=[]
        for _ in range(20):
            t0=time.perf_counter()
            _fp8_gemm_kernel[grid](x,w,y,s,M,N,K,x.stride(0),x.stride(1),w.stride(1),w.stride(0),y.stride(0),y.stride(1),HAS_TAIL=False,BLOCK_M=bm,BLOCK_N=bn,BLOCK_K=bk,GROUP_M=gm,num_warps=nw,num_stages=ns)
            torch.cuda.synchronize()
            times.append((time.perf_counter()-t0)*1000)
        ms=statistics.median(times)
        tflops=2*M*N*K/ms/1e6
        print(f'bm={bm} bn={bn} bk={bk} nw={nw} ns={ns} gm={gm} ms={ms:.3f} tflops={tflops:.0f}')
    except Exception as e:
        print(f'bm={bm} bn={bn} FAIL {type(e).__name__}: {e}')
" 2>&1
tool
stdout (4 chars)
null
assistant
shell
args
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        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
  

... (3306 more chars)
command (1221 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch, time, statistics, triton, sys
sys.path.insert(0,'.')
from src.eval.timing import time_fn, _l2_flush
from solution import _fp8_gemm_skinny_kernel

M,N,K = 32, 8192, 8192
x = torch.randn(M,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
w = torch.randn(N,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
s = torch.ones(N, device='cuda', dtype=torch.float32)
y = torch.empty(M,N,device='cuda',dtype=torch.bfloat16)

for bm,bn,bk,nw,ns in [(32,128,256,4,3),(32,128,128,4,2),(16,128,256,4,3),(32,256,128,8,2)]:
    grid=(triton.cdiv(N,bn),)
    fn = lambda: _fp8_gemm_skinny_kernel[grid](x,w,y,s,M,N,K,x.stride(0),x.stride(1),w.stride(1),w.stride(0),y.stride(0),y.stride(1),HAS_TAIL=False,BLOCK_M=bm,BLOCK_N=bn,BLOCK_K=bk,num_warps=nw,num_stages=ns)
    for _ in range(10): fn()
    torch.cuda.synchronize()
    times=[]
    for _ in range(30):
        _l2_flush(); torch.cuda.synchronize()
        t0=time.perf_counter(); fn(); torch.cuda.synchronize()
        times.append((time.perf_counter()-t0)*1000)
    ms=statistics.median(times)
    print(f'bm={bm} bn={bn} bk={bk} ms={ms:.4f} gbps={(M*K+N*K+M*N*2)/ms/1e6:.0f}')
" 2>&1
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "<1331 chars \u2014 see below>",
  "workingDirectory": "",
  "timeout": 120000,
  "toolCallId": "tool_4cf7cc81-d085-468f-8449-c34ac2f32a6",
  "simpleCommands": [
    "cd",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
  

... (3525 more chars)
command (1331 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch, time, statistics, triton
from solution import _fp8_gemm_kernel

M,N,K = 4096,14336,4096
x = torch.randn(M,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
w = torch.randn(N,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
s = torch.ones(N, device='cuda', dtype=torch.float32)
y = torch.empty(M,N,device='cuda',dtype=torch.bfloat16)

configs = [
    (128,256,128,8,2,4),(128,128,128,8,3,8),(256,128,128,8,2,4),(128,256,128,8,2,4)
]
for bm,bn,bk,nw,ns,gm in configs:
    grid=(triton.cdiv(M,bm)*triton.cdiv(N,bn),)
    for _ in range(5):
        _fp8_gemm_kernel[grid](x,w,y,s,M,N,K,x.stride(0),x.stride(1),w.stride(1),w.stride(0),y.stride(0),y.stride(1),HAS_TAIL=False,BLOCK_M=bm,BLOCK_N=bn,BLOCK_K=bk,GROUP_M=gm,num_warps=nw,num_stages=ns)
    torch.cuda.synchronize()
    times=[]
    for _ in range(20):
        t0=time.perf_counter()
        _fp8_gemm_kernel[grid](x,w,y,s,M,N,K,x.stride(0),x.stride(1),w.stride(1),w.stride(0),y.stride(0),y.stride(1),HAS_TAIL=False,BLOCK_M=bm,BLOCK_N=bn,BLOCK_K=bk,GROUP_M=gm,num_warps=nw,num_stages=ns)
        torch.cuda.synchronize()
        times.append((time.perf_counter()-t0)*1000)
    ms=statistics.median(times)
    print(f'bm={bm} bn={bn} ms={ms:.3f} tflops={2*M*N*K/ms/1e6:.0f}')
" 2>&1
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (69 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,63 +1,6 @@
-def _fp8_gemm(x: torch.Tensor, weight: torch.Tensor, weight_scale: torch.Tensor) -> torch.Tensor:
-    M, K = x.shape
-    N, K_w = weight.shape
-    assert K == K_w
-
-    block_k = 128
-    pad_k = (block_k - (K % block_k)) % block_k
-    if pad_k:
-        x = torch.nn.functional.pad(x, (0, pad_k))
-        weight = torch.nn.functional.pad(weight, (0, pad_k))
-        K = K + pad_k
-
-    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
-    block_m, block_n, block_k, num_warps, num_stages, group_m = _pick_config(M, N)
-
+def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
     if M <= 64:
-        grid = (triton.cdiv(N, block_n),)
-        _fp8_gemm_skinny_kernel[grid](
-            x,
-            weight,
-            y,
-            weight_scale,
-            M,
-            N,
-            K,
-            x.stride(0),
-            x.stride(1),
-            weight.stride(1),
-            weight.stride(0),
-            y.stride(0),
-            y.stride(1),
-            HAS_TAIL=False,
-            BLOCK_M=block_m,
-            BLOCK_N=block_n,
-            BLOCK_K=block_k,
-            num_warps=num_warps,
-            num_stages=num_stages,
-        )
-    else:
-        grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
-        _fp8_gemm_kernel[grid](
-            x,
-            weight,
-            y,
-            weight_scale,
-            M,
-            N,
-            K,
-            x.stride(0),
-            x.stride(1),
-            weight.stride(1),
-            weight.stride(0),
-            y.stride(0),
-            y.stride(1),
-            HAS_TAIL=False,
-            BLOCK_M=block_m,
-            BLOCK_N=block_n,
-            BLOCK_K=block_k,
-            GROUP_M=group_m,
-            num_warps=num_warps,
-            num_stages=num_stages,
-        )
-    return y+        return 16, 128, 256, 4, 3, 1
+    if N >= 12000:
+        return 128, 256, 128, 8, 2, 4
+    return 128, 256, 128, 8, 2, 4
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<216 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
tool
stdout (4 chars)
null
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (31 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,6 +1,24 @@
-def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
-    if M <= 64:
-        return 16, 128, 256, 4, 3, 1
-    if N >= 12000:
-        return 128, 256, 128, 8, 2, 4
-    return 128, 256, 128, 8, 2, 4+class Model(nn.Module):
+    def __init__(self, M: int, N: int, K: int):
+        super().__init__()
+        self.M, self.N, self.K = M, N, K
+        w = torch.empty(N, K, dtype=torch.bfloat16)
+        nn.init.normal_(w, std=0.02)
+        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
+        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
+        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
+
+        pad_k = (128 - (K % 128)) % 128
+        if pad_k:
+            w_fp8 = torch.nn.functional.pad(w_fp8, (0, pad_k))
+            self._k_padded = K + pad_k
+        else:
+            self._k_padded = K
+        self.register_buffer("weight", w_fp8)
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        K = x.shape[1]
+        pad_k = self._k_padded - K
+        if pad_k:
+            x = torch.nn.functional.pad(x, (0, pad_k))
+        return _fp8_gemm(x, self.weight, self.weight_scale, self.M)
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<953 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (84 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,24 +1,61 @@
-class Model(nn.Module):
-    def __init__(self, M: int, N: int, K: int):
-        super().__init__()
-        self.M, self.N, self.K = M, N, K
-        w = torch.empty(N, K, dtype=torch.bfloat16)
-        nn.init.normal_(w, std=0.02)
-        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
-        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
-        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
+def _fp8_gemm(
+    x: torch.Tensor,
+    weight: torch.Tensor,
+    weight_scale: torch.Tensor,
+    M: int,
+) -> torch.Tensor:
+    K = x.shape[1]
+    N, K_w = weight.shape
+    assert K == K_w
 
-        pad_k = (128 - (K % 128)) % 128
-        if pad_k:
-            w_fp8 = torch.nn.functional.pad(w_fp8, (0, pad_k))
-            self._k_padded = K + pad_k
-        else:
-            self._k_padded = K
-        self.register_buffer("weight", w_fp8)
+    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
+    block_m, block_n, block_k, num_warps, num_stages, group_m = _pick_config(M, N)
 
-    def forward(self, x: torch.Tensor) -> torch.Tensor:
-        K = x.shape[1]
-        pad_k = self._k_padded - K
-        if pad_k:
-            x = torch.nn.functional.pad(x, (0, pad_k))
-        return _fp8_gemm(x, self.weight, self.weight_scale, self.M)+    if M <= 64:
+        grid = (triton.cdiv(N, block_n),)
+        _fp8_gemm_skinny_kernel[grid](
+            x,
+            weight,
+            y,
+            weight_scale,
+            M,
+            N,
+            K,
+            x.stride(0),
+            x.stride(1),
+            weight.stride(1),
+            weight.stride(0),
+            y.stride(0),
+            y.stride(1),
+            HAS_TAIL=False,
+            BLOCK_M=block_m,
+            BLOCK_N=block_n,
+            BLOCK_K=block_k,
+            num_warps=num_warps,
+            num_stages=num_stages,
+        )
+    else:
+        grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
+        _fp8_gemm_kernel[grid](
+            x,
+            weight,
+            y,
+            weight_scale,
+            M,
+            N,
+            K,
+            x.stride(0),
+            x.stride(1),
+            weight.stride(1),
+            weight.stride(0),
+            y.stride(0),
+            y.stride(1),
+            HAS_TAIL=False,
+            BLOCK_M=block_m,
+            BLOCK_N=block_n,
+            BLOCK_K=block_k,
+            GROUP_M=group_m,
+            num_warps=num_warps,
+            num_stages=num_stages,
+        )
+    return y
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<1538 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python benchmark.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_8f2ddfa0-9d97-4930-93b2-4a37e825efb",
  "simpleCommands": [
    "cd",
    "uv",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText

... (1469 more chars)
tool
stdout (856 chars)
failure:
  command: 'cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python benchmark.py 2>&1'
  workingDirectory: ''
  exitCode: 1
  signal: ''
  stdout:
    FAIL: state_dict mismatch at shape 1 ({'M': 4096, 'N': 4096, 'K': 4127}): Error(s) in loading state_dict for Model:
    	size mismatch for weight: copying a param with shape torch.Size([4096, 4127]) from checkpoint, the shape in current model is torch.Size([4096, 4224]).
  stderr: ''
  executionTime: 2357
  interleavedOutput:
    FAIL: state_dict mismatch at shape 1 ({'M': 4096, 'N': 4096, 'K': 4127}): Error(s) in loading state_dict for Model:
    	size mismatch for weight: copying a param with shape torch.Size([4096, 4127]) from checkpoint, the shape in current model is torch.Size([4096, 4224]).
  aborted: False
  localExecutionTimeMs: 2295
isBackground: False
assistant
Weight pre-padding breaks `state_dict` loading — I'll pad at runtime instead while keeping the registered buffers unchanged.
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (80 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,61 +1,19 @@
-def _fp8_gemm(
-    x: torch.Tensor,
-    weight: torch.Tensor,
-    weight_scale: torch.Tensor,
-    M: int,
-) -> torch.Tensor:
-    K = x.shape[1]
-    N, K_w = weight.shape
-    assert K == K_w
+class Model(nn.Module):
+    def __init__(self, M: int, N: int, K: int):
+        super().__init__()
+        self.M, self.N, self.K = M, N, K
+        w = torch.empty(N, K, dtype=torch.bfloat16)
+        nn.init.normal_(w, std=0.02)
+        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
+        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
+        self.register_buffer("weight", w_fp8)
+        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
 
-    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
-    block_m, block_n, block_k, num_warps, num_stages, group_m = _pick_config(M, N)
-
-    if M <= 64:
-        grid = (triton.cdiv(N, block_n),)
-        _fp8_gemm_skinny_kernel[grid](
-            x,
-            weight,
-            y,
-            weight_scale,
-            M,
-            N,
-            K,
-            x.stride(0),
-            x.stride(1),
-            weight.stride(1),
-            weight.stride(0),
-            y.stride(0),
-            y.stride(1),
-            HAS_TAIL=False,
-            BLOCK_M=block_m,
-            BLOCK_N=block_n,
-            BLOCK_K=block_k,
-            num_warps=num_warps,
-            num_stages=num_stages,
-        )
-    else:
-        grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
-        _fp8_gemm_kernel[grid](
-            x,
-            weight,
-            y,
-            weight_scale,
-            M,
-            N,
-            K,
-            x.stride(0),
-            x.stride(1),
-            weight.stride(1),
-            weight.stride(0),
-            y.stride(0),
-            y.stride(1),
-            HAS_TAIL=False,
-            BLOCK_M=block_m,
-            BLOCK_N=block_n,
-            BLOCK_K=block_k,
-            GROUP_M=group_m,
-            num_warps=num_warps,
-            num_stages=num_stages,
-        )
-    return y+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        weight = self.weight
+        K = x.shape[1]
+        pad_k = (128 - (K % 128)) % 128
+        if pad_k:
+            x = torch.nn.functional.pad(x, (0, pad_k))
+            weight = torch.nn.functional.pad(weight, (0, pad_k))
+        return _fp8_gemm(x, weight, self.weight_scale, self.M)
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<841 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python benchmark.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_ba98d3b1-154e-42ac-9bfc-98ad436b62c",
  "simpleCommands": [
    "cd",
    "uv",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText

... (1476 more chars)
tool
stdout (692 chars)
failure:
  command: 'cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python benchmark.py 2>&1'
  workingDirectory: ''
  exitCode: 1
  signal: ''
  stdout:
    FAIL: shape 2 {'M': 32, 'N': 8192, 'K': 8192} seed 42 case nominal: tolerance exceeded: max_abs_diff=120835 max_rel_diff=5.1968e+34 bad=127868/262144 worst_idx=(27, 65) (atol=0.2, rtol=0.2)
  stderr: ''
  executionTime: 4604
  interleavedOutput:
    FAIL: shape 2 {'M': 32, 'N': 8192, 'K': 8192} seed 42 case nominal: tolerance exceeded: max_abs_diff=120835 max_rel_diff=5.1968e+34 bad=127868/262144 worst_idx=(27, 65) (atol=0.2, rtol=0.2)
  aborted: False
  localExecutionTimeMs: 4541
isBackground: False
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (23 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,19 +1,3 @@
-class Model(nn.Module):
-    def __init__(self, M: int, N: int, K: int):
-        super().__init__()
-        self.M, self.N, self.K = M, N, K
-        w = torch.empty(N, K, dtype=torch.bfloat16)
-        nn.init.normal_(w, std=0.02)
-        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
-        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
-        self.register_buffer("weight", w_fp8)
-        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
-
-    def forward(self, x: torch.Tensor) -> torch.Tensor:
-        weight = self.weight
-        K = x.shape[1]
-        pad_k = (128 - (K % 128)) % 128
-        if pad_k:
-            x = torch.nn.functional.pad(x, (0, pad_k))
-            weight = torch.nn.functional.pad(weight, (0, pad_k))
-        return _fp8_gemm(x, weight, self.weight_scale, self.M)+def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
+    if M <= 64:
+        return 32, 128, 256, 4, 3, 1
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<125 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python benchmark.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_739e3a56-eea0-45f5-abc5-91f301ce61f",
  "simpleCommands": [
    "cd",
    "uv",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText

... (1478 more chars)
tool
stdout (4 chars)
null
assistant
Cleaning up the kernels and adding a padded-weight cache to squeeze out more performance.
assistant
read /workspace/problems/01_fp8_gemm/solution.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py"
}
tool
stdout (6550 chars) — TRUNCATED
"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
import torch
import torch.nn as nn
import triton
import triton.language as tl

E4M3_MAX = 448.0


@triton.jit
def _fp8_gemm_kernel(
    A,
    B,
    C,
    Scales,
    M,
    N,
    K,
    stride_am,
    stride_ak,
    stride_bk,
    stride_bn,
    stride_cm,
    stride_cn,
    HAS_TAIL: tl.constexpr,
    BLOCK_M: tl.constexpr,
    BLOCK_N: tl.constexpr,
    BLOCK_K: tl.constexpr,
    GROUP_M: tl.constexpr,
):
    pid = tl.program_id(0)
    num_pid_m = tl.cdiv(M, BLOCK_M)
    num_pid_n = tl.cdiv(N, BLOCK_N)
    num_pid_in_group = GROUP_M * num_pid_n
    group_id = pid // num_pid_in_group
    first_pid_m = group_id * GROUP_M
    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
    pid_m = first_pid_m + (pid % group_size_m)
    pid_n = (pid % num_pid_in_group) // group_size_m

    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
    offs_k = tl.arange(0, BLOCK_K)

    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn

    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)

    full_k = (K // BLOCK_K) * BLOCK_K
    for k in range(0, full_k, BLOCK_K):
        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
        acc = tl.dot(a, b, acc)
        a_ptrs += BLOCK_K * stride_ak
     

... (5050 more chars)
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (214 lines — TRUNCATED)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,3 +1,211 @@
+"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
+import torch
+import torch.nn as nn
+import triton
+import triton.language as tl
+
+E4M3_MAX = 448.0
+
+
+@triton.jit
+def _fp8_gemm_kernel(
+    A,
+    B,
+    C,
+    Scales,
+    M,
+    N,
+    K,
+    stride_am,
+    stride_ak,
+    stride_bk,
+    stride_bn,
+    stride_cm,
+    stride_cn,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    GROUP_M: tl.constexpr,
+    NUM_STAGES: tl.constexpr,
+):
+    pid = tl.program_id(0)
+    num_pid_m = tl.cdiv(M, BLOCK_M)
+    num_pid_n = tl.cdiv(N, BLOCK_N)
+    num_pid_in_group = GROUP_M * num_pid_n
+    group_id = pid // num_pid_in_group
+    first_pid_m = group_id * GROUP_M
+    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
+    pid_m = first_pid_m + (pid % group_size_m)
+    pid_n = (pid % num_pid_in_group) // group_size_m
+
+    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
+    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
+    offs_k = tl.arange(0, BLOCK_K)
+
+    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
+    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
+
+    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
+    for k in tl.range(0, K, BLOCK_K, num_stages=NUM_STAGES):
+        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
+        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
+        acc = tl.dot(a, b, acc)
+        a_ptrs += BLOCK_K * stride_ak
+        b_ptrs += BLOCK_K * stride_bk
+
+    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
+    acc = acc * scales[None, :]
+
+    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
+    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
+
+
+@triton.jit
+def _fp8_gemm_skinny_kernel(
+    A,
+    B,
+    C,
+    Scales,
+    M,
+    N,
+    K,
+    stride_am,
+    stride_ak,
+    stride_bk,
+    stride_bn,
+    stride_cm,
+    stride_cn,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    NUM_STAGES: tl.constexpr,
+):
+    pid_n = tl.program_id(0)
+    offs_m = tl.arange(0, BLOCK_M)
+    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
+    offs_k = tl.arange(0, BLOCK_K)
+
+    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
+    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
+
+    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
+    for k in tl.range(0, K, BLOCK_K, num_stages=NUM_STAGES):
+        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
+        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
+        acc = tl.dot(a, b, acc)
+        a_ptrs += BLOCK_K * stride_ak
+        b_ptrs += BLOCK_K * stride_bk
+
+    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
+    acc = acc * scales[None, :]
+
+    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
+    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
+
+
 def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
     if M <= 64:
-        return 32, 128, 256, 4, 3, 1+        return 32, 128, 256, 4, 3, 1
+    if N >= 12000:
+        return 128, 256, 128, 8, 2, 4
+    return 128, 256, 128, 8, 2, 4
+
+
+def _fp8_gemm(
+    x: torch.Tensor,
+    weight: torch.Tensor,
+    weight_scale: torch.Tensor,
+    M: int,
+) -> torch.Tensor:
+    K = x.shape[1]
+    N, K_w = weight.shape
+    assert K == K_w
+
+    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
+    block_m, block_n, block_k, num_warps, num_stages, group_m = _pick_config(M, N)
+
+    if M <= 64:
+        grid = (triton.cdiv(N, block_n),)
+        _fp8_gemm_skinny_kernel[grid](
+            x,
+            weight,
+            y,
+            weight_scale,
+            M,
+            N,
+            K,
+            x.stride(0),
+            x.stride(1),
+            weight.stride(1),
+            weight.stride(0),
+            y.stride(0),
+            y.stride(1),
+            BLOCK_M=block_m,
+            BLOCK_N=block_n,
+            BLOCK_K=block_k,
+            NUM_STAGES=num_stages,
+            num_warps=num_warps,
+        )
+    else:
+        grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
+        _fp8_gemm_kernel[grid](
+            x,
+            weight,
+            y,
+            weight_scale,
+            M,
+            N,
+            K,
+            x.stride(0),
+            x.stride(1),
+            weight.stride(1),
+            weight.stride(0),
+            y.stride(0),
+            y.stride(1),
+            BLOCK_M=block_m,
+            BLOCK_N=block_n,
+            BLOCK_K=block_k,
+            GROUP_M=group_m,
+            NUM_STAGES=num_stages,
+            num_warps=num_warps,
+        )
+    return y
+
+
+class Model(nn.Module):
+    def __init__(self, M: int, N: int, K: int):
+        super().__init__()
+        self.M, self.N, self.K = M, N, K
+        w = torch.empty(N, K, dtype=torch.bfloat16)
+        nn.init.normal_(w, std=0.02)
+        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
+        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
+        self.register_buffer("weight", w_fp8)
+        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
+        self._weight_padded: torch.Tensor | None = None
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        K = x.shape[1]
+        pad_k = (128 - (K % 128)) % 128
+        if pad_k:
+            if self._weight_padded is None:
+                self._weight_padded = torch.nn.functional.pad(self.weight, (0, pad_k))
+            x = torch.nn.functional.pad(x, (0, pad_k))
+            weight = self._weight_padded
+        else:
+

... (280 more chars)
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<5914 chars \u2014 see diff>"
}
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python benchmark.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_1951e202-1aa0-4eb6-b3c6-f28882a2717",
  "simpleCommands": [
    "cd",
    "uv",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
    "executableCommands": [
      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText

... (1466 more chars)
tool
stdout (4 chars)
null
tool
stdout (732 chars)
failure:
  command: 'cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python benchmark.py 2>&1'
  workingDirectory: ''
  exitCode: 1
  signal: ''
  stdout:
    FAIL: shape 1 {'M': 4096, 'N': 4096, 'K': 4127} seed 42 case small_weight: tolerance exceeded: max_abs_diff=16.5801 max_rel_diff=3.70181e+07 bad=16763441/16777216 worst_idx=(2349, 1017) (atol=0.003, rtol=0.05)
  stderr: ''
  executionTime: 2818
  interleavedOutput:
    FAIL: shape 1 {'M': 4096, 'N': 4096, 'K': 4127} seed 42 case small_weight: tolerance exceeded: max_abs_diff=16.5801 max_rel_diff=3.70181e+07 bad=16763441/16777216 worst_idx=(2349, 1017) (atol=0.003, rtol=0.05)
  aborted: False
  localExecutionTimeMs: 2730
isBackground: False
assistant
The padded-weight cache goes stale under numeric stress — I'll invalidate it when weights change.
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (217 lines — TRUNCATED)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,211 +1,17 @@
-"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
-import torch
-import torch.nn as nn
-import triton
-import triton.language as tl
-
-E4M3_MAX = 448.0
-
-
-@triton.jit
-def _fp8_gemm_kernel(
-    A,
-    B,
-    C,
-    Scales,
-    M,
-    N,
-    K,
-    stride_am,
-    stride_ak,
-    stride_bk,
-    stride_bn,
-    stride_cm,
-    stride_cn,
-    BLOCK_M: tl.constexpr,
-    BLOCK_N: tl.constexpr,
-    BLOCK_K: tl.constexpr,
-    GROUP_M: tl.constexpr,
-    NUM_STAGES: tl.constexpr,
-):
-    pid = tl.program_id(0)
-    num_pid_m = tl.cdiv(M, BLOCK_M)
-    num_pid_n = tl.cdiv(N, BLOCK_N)
-    num_pid_in_group = GROUP_M * num_pid_n
-    group_id = pid // num_pid_in_group
-    first_pid_m = group_id * GROUP_M
-    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
-    pid_m = first_pid_m + (pid % group_size_m)
-    pid_n = (pid % num_pid_in_group) // group_size_m
-
-    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
-    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
-    offs_k = tl.arange(0, BLOCK_K)
-
-    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
-    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
-
-    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
-    for k in tl.range(0, K, BLOCK_K, num_stages=NUM_STAGES):
-        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
-        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
-        acc = tl.dot(a, b, acc)
-        a_ptrs += BLOCK_K * stride_ak
-        b_ptrs += BLOCK_K * stride_bk
-
-    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
-    acc = acc * scales[None, :]
-
-    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
-    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
-
-
-@triton.jit
-def _fp8_gemm_skinny_kernel(
-    A,
-    B,
-    C,
-    Scales,
-    M,
-    N,
-    K,
-    stride_am,
-    stride_ak,
-    stride_bk,
-    stride_bn,
-    stride_cm,
-    stride_cn,
-    BLOCK_M: tl.constexpr,
-    BLOCK_N: tl.constexpr,
-    BLOCK_K: tl.constexpr,
-    NUM_STAGES: tl.constexpr,
-):
-    pid_n = tl.program_id(0)
-    offs_m = tl.arange(0, BLOCK_M)
-    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
-    offs_k = tl.arange(0, BLOCK_K)
-
-    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
-    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
-
-    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
-    for k in tl.range(0, K, BLOCK_K, num_stages=NUM_STAGES):
-        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
-        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
-        acc = tl.dot(a, b, acc)
-        a_ptrs += BLOCK_K * stride_ak
-        b_ptrs += BLOCK_K * stride_bk
-
-    scales = tl.load(Scales + offs_n, mask=offs_n < N, other=1.0)
-    acc = acc * scales[None, :]
-
-    c_ptrs = C + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
-    tl.store(c_ptrs, acc.to(tl.bfloat16), mask=(offs_m[:, None] < M) & (offs_n[None, :] < N))
-
-
-def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
-    if M <= 64:
-        return 32, 128, 256, 4, 3, 1
-    if N >= 12000:
-        return 128, 256, 128, 8, 2, 4
-    return 128, 256, 128, 8, 2, 4
-
-
-def _fp8_gemm(
-    x: torch.Tensor,
-    weight: torch.Tensor,
-    weight_scale: torch.Tensor,
-    M: int,
-) -> torch.Tensor:
-    K = x.shape[1]
-    N, K_w = weight.shape
-    assert K == K_w
-
-    y = torch.empty((M, N), device=x.device, dtype=torch.bfloat16)
-    block_m, block_n, block_k, num_warps, num_stages, group_m = _pick_config(M, N)
-
-    if M <= 64:
-        grid = (triton.cdiv(N, block_n),)
-        _fp8_gemm_skinny_kernel[grid](
-            x,
-            weight,
-            y,
-            weight_scale,
-            M,
-            N,
-            K,
-            x.stride(0),
-            x.stride(1),
-            weight.stride(1),
-            weight.stride(0),
-            y.stride(0),
-            y.stride(1),
-            BLOCK_M=block_m,
-            BLOCK_N=block_n,
-            BLOCK_K=block_k,
-            NUM_STAGES=num_stages,
-            num_warps=num_warps,
-        )
-    else:
-        grid = (triton.cdiv(M, block_m) * triton.cdiv(N, block_n),)
-        _fp8_gemm_kernel[grid](
-            x,
-            weight,
-            y,
-            weight_scale,
-            M,
-            N,
-            K,
-            x.stride(0),
-            x.stride(1),
-            weight.stride(1),
-            weight.stride(0),
-            y.stride(0),
-            y.stride(1),
-            BLOCK_M=block_m,
-            BLOCK_N=block_n,
-            BLOCK_K=block_k,
-            GROUP_M=group_m,
-            NUM_STAGES=num_stages,
-            num_warps=num_warps,
-        )
-    return y
-
-
-class Model(nn.Module):
-    def __init__(self, M: int, N: int, K: int):
-        super().__init__()
-        self.M, self.N, self.K = M, N, K
-        w = torch.empty(N, K, dtype=torch.bfloat16)
-        nn.init.normal_(w, std=0.02)
-        s = (w.float().abs().amax(dim=1, keepdim=True) / E4M3_MAX).clamp(min=1e-12)
-        w_fp8 = (w.float() / s).to(torch.float8_e4m3fn)
         self.register_buffer("weight", w_fp8)
         self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
         self._weight_padded: torch.Tensor | None = None
+        self._weight_version: int = -1
 
     def forward(self, x: torch.Tensor) -> torch.Tensor:
         K = x.shape[1]
         pad_k = (128 - (K % 128)) % 128
         if pad_k:
-            if self._weight_padded is None:
+            if self._weight_padded is None or self._weight_version != self.weight._version:
                 self._weight_padded = torch.nn.functional.pad(self.weight, (0, pad_k))
+                

... (501 more chars)
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py",
  "streamContent": "<800 chars \u2014 see diff>"
}
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "cd /workspace/problems/01_fp8_gemm && uv run python check.py 2>&1 && uv run python benchmark.py 2>&1",
  "workingDirectory": "",
  "timeout": 300000,
  "toolCallId": "tool_afdbcdfe-c8b7-4c03-a76f-ccca311315b",
  "simpleCommands": [
    "cd",
    "uv",
    "uv"
  ],
  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
    "parsingFailed": false,
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      {
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        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText

... (1459 more chars)
tool
stdout (4 chars)
null
assistant
shell
args
{
  "command": "<1356 chars \u2014 see below>",
  "workingDirectory": "",
  "timeout": 120000,
  "toolCallId": "tool_8e7c1272-ff50-43cc-9c8d-56247ba3c35",
  "simpleCommands": [
    "cd",
    "uv"
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  "hasInputRedirect": false,
  "hasOutputRedirect": true,
  "parsingResult": {
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      {
        "name": "cd",
        "args": [
          {
            "type": "word",
            "value": "/workspace/problems/01_fp8_gemm"
          }
        ],
        "fullText": "cd /workspace/problems/01_fp8_gemm"
      },
      {
        "name": "uv",
  

... (3588 more chars)
command (1356 chars)
cd /workspace/problems/01_fp8_gemm && uv run python -c "
import torch, statistics, triton, sys
sys.path.insert(0,'.')
from src.eval.timing import _l2_flush
from solution import _fp8_gemm_kernel

M,N,K = 4096,4096,4096
x = torch.randn(M,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
w = torch.randn(N,K,device='cuda',dtype=torch.bfloat16).to(torch.float8_e4m3fn)
s = torch.ones(N, device='cuda', dtype=torch.float32)
y = torch.empty(M,N,device='cuda',dtype=torch.bfloat16)

configs = [
    (128,256,128,8,2,4),(256,128,128,8,2,4),(128,128,128,8,3,8),(128,256,128,8,3,4)
]
for bm,bn,bk,nw,ns,gm in configs:
    grid=(triton.cdiv(M,bm)*triton.cdiv(N,bn),)
    fn = lambda bm=bm,bn=bn,bk=bk,nw=nw,ns=ns,gm=gm: _fp8_gemm_kernel[grid](x,w,y,s,M,N,K,x.stride(0),x.stride(1),w.stride(1),w.stride(0),y.stride(0),y.stride(1),BLOCK_M=bm,BLOCK_N=bn,BLOCK_K=bk,GROUP_M=gm,NUM_STAGES=ns,num_warps=nw)
    for _ in range(10): fn()
    torch.cuda.synchronize()
    times=[]
    for _ in range(30):
        _l2_flush(); torch.cuda.synchronize()
        e0=torch.cuda.Event(enable_timing=True); e1=torch.cuda.Event(enable_timing=True)
        e0.record(); fn(); e1.record(); torch.cuda.synchronize()
        times.append(e0.elapsed_time(e1))
    ms=statistics.median(times)
    print(f'bm={bm} bn={bn} ns={ns} ms={ms:.4f} tflops={2*M*N*K/ms/1e6:.0f}')
" 2>&1
tool
stdout (4 chars)
null
assistant
edit /workspace/problems/01_fp8_gemm/solution.py
diff (24 lines)
--- a//workspace/problems/01_fp8_gemm/solution.py
+++ b//workspace/problems/01_fp8_gemm/solution.py
@@ -1,17 +1,6 @@
-        self.register_buffer("weight", w_fp8)
-        self.register_buffer("weight_scale", s.squeeze(1).to(torch.float32))
-        self._weight_padded: torch.Tensor | None = None
-        self._weight_version: int = -1
-
-    def forward(self, x: torch.Tensor) -> torch.Tensor:
-        K = x.shape[1]
-        pad_k = (128 - (K % 128)) % 128
-        if pad_k:
-            if self._weight_padded is None or self._weight_version != self.weight._version:
-                self._weight_padded = torch.nn.functional.pad(self.weight, (0, pad_k))
-                self._weight_version = self.weight._version
-            x = torch.nn.functional.pad(x, (0, pad_k))
-            weight = self._weight_padded
-        else:
-            weight = self.weight
-        return _fp8_gemm(x, weight, self.weight_scale, self.M)+def _pick_config(M: int, N: int) -> tuple[int, int, int, int, int, int]:
+    if M <= 64:
+        return 32, 128, 256, 4, 3, 1
+    if N >= 12000:
+        return 128, 256, 128, 8, 3, 4
+    return 128, 256, 128, 8, 3, 4
args
{
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  "streamContent": "<216 chars \u2014 see diff>"
}
tool
stdout (4 chars)
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assistant
shell
args
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... (1478 more chars)
tool
stdout (4 chars)
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assistant
delete /workspace/problems/01_fp8_gemm/test_triton_fp8.py
args
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tool
stdout (4 chars)
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assistant
read /workspace/problems/01_fp8_gemm/solution.py
args
{
  "path": "/workspace/problems/01_fp8_gemm/solution.py"
}
tool
stdout (6061 chars) — TRUNCATED
"""FP8 e4m3 GEMM via Triton FP8 tensor-core tl.dot + per-channel scale."""
import torch
import torch.nn as nn
import triton
import triton.language as tl

E4M3_MAX = 448.0


@triton.jit
def _fp8_gemm_kernel(
    A,
    B,
    C,
    Scales,
    M,
    N,
    K,
    stride_am,
    stride_ak,
    stride_bk,
    stride_bn,
    stride_cm,
    stride_cn,
    BLOCK_M: tl.constexpr,
    BLOCK_N: tl.constexpr,
    BLOCK_K: tl.constexpr,
    GROUP_M: tl.constexpr,
    NUM_STAGES: tl.constexpr,
):
    pid = tl.program_id(0)
    num_pid_m = tl.cdiv(M, BLOCK_M)
    num_pid_n = tl.cdiv(N, BLOCK_N)
    num_pid_in_group = GROUP_M * num_pid_n
    group_id = pid // num_pid_in_group
    first_pid_m = group_id * GROUP_M
    group_size_m = min(num_pid_m - first_pid_m, GROUP_M)
    pid_m = first_pid_m + (pid % group_size_m)
    pid_n = (pid % num_pid_in_group) // group_size_m

    offs_m = pid_m * BLOCK_M + tl.arange(0, BLOCK_M)
    offs_n = pid_n * BLOCK_N + tl.arange(0, BLOCK_N)
    offs_k = tl.arange(0, BLOCK_K)

    a_ptrs = A + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
    b_ptrs = B + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn

    acc = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
    for k in tl.range(0, K, BLOCK_K, num_stages=NUM_STAGES):
        a = tl.load(a_ptrs, mask=offs_m[:, None] < M, other=0.0)
        b = tl.load(b_ptrs, mask=offs_n[None, :] < N, other=0.0)
        acc = tl.dot(a, b, acc)
        a_ptrs += BLOCK_K * stride_ak
        b_ptrs += BLO

... (4561 more chars)
assistant
Implemented a Triton FP8 tensor-core GEMM in `solution.py`. `check.py` passes and benchmark results are below. ## Approach **Kernel:** Two Triton kernels using `tl.dot` on `float8_e4m3fn` with fp32 accumulation, then per-channel `weight_scale`, output as bf16. 1. **`_fp8_gemm_kernel`** — general case with L2-swizzled 1D grid (`GROUP_M` reordering) 2. **`_fp8_gemm_skinny_kernel`** — decode path (`M ≤ 64`), parallelized over N only **Key optimizations:** - **K-padding to 128** — When `K % 128 ≠ 0` (e.g. K=4127), pad x and weight with fp8 zeros so the inner loop never needs predicated K tails. Masked tails broke Triton pipelining and caused a ~10× slowdown. - **`tl.range(..., num_stages=3)`** — Software pipelining for HBM latency hiding - **Shape-specific tiles:** - Square / Llama: `128×256×128`, 8 warps, 3 stages - Skinny decode: `32×128×256`, 4 warps, 3 stages - **Cached padded weight** — Invalidated via `weight._version` for numeric-stress cases ## Results (`benchmark.py`) | Shape | TFLOPS | Peak Fraction | Notes | |-------|--------|---------------|-------| | 4096³ | **610** | 61.0% | vs cuBLAS SOTA ~541 | | 4096³ K=4127 | **534** | 53.5% | cuBLAS `_scaled_mm` fails (K%16≠0) | | 32×8192×8192 | **73** | 7.3% | 1151 GB/s (64% DRAM peak); memory-bound | | 4096×14336×4096 | **671** | 67.1% | vs SOTA ~654 | **Geomean peak_fraction: 0.355** (35.5% of 1000 TFLOPS FP8 roofline) The solution beats the cuBLAS SOTA baseline on every shape where SOTA runs, and handles K=4127 which cuBLAS cannot.