./kernelbenchhardv3runsopencode · ?
opencode / ? session: ses_22e484751ffexgNc7BKAYudO0I cwd: ?
harness
opencode
model
?
turns
20
tools called
12
events
32
input toks
67,664
output toks
666
cache hit
0
final answer
result.json
Let me look at a similar existing solution for patterns.
{
    "problem": "04_kahan_softmax",
    "harness": "opencode",
    "model": "openrouter-pinned/qwen/qwen3.6-27b",
    "reasoning_effort": "",
    "has_solution": false,
    "correct": false,
    "peak_fraction": null,
    "elapsed_seconds": 698,
    "harness_exit_code": 0,
    "session_complete": true,
    "usage": {"input_tokens": 67664, "output_tokens": 666, "cache_read_tokens": 0, "cache_creation_tokens": 0, "reasoning_tokens": 267, "total_cost_usd": null}
}

timeline (32 events)

assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax"
}
tool
stdout (210 chars)
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax</path>
<type>directory</type>
<entries>
benchmark.py
check.py
problem.yaml
PROMPT.txt
reference.py
shapes.py
sota.py

(7 entries)
</entries>
assistant
I'll start by reading all the relevant files to understand the interface and requirements.
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in 13564out 65cache_r 0cache_w 0
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read /home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/reference.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/reference.py"
}
tool
stdout (2092 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/reference.py</path>
<type>file</type>
<content>
1: """Naive softmax over the last dim, computed in fp64 for ground-truth.
2: 
3: The reference deliberately runs in float64 so that fp16 / fp32 accumulation
4: drift in agent solutions is exposed by the tight tolerance in problem.yaml.
5: The agent's job is to produce an fp32 softmax whose values match this
6: double-precision reference within atol=rtol=1e-5 — this requires either
7: fp32 accumulation or compensated (Kahan) summation when vocab is large.
8: """
9: import torch
10: import torch.nn as nn
11: 
12: OP_TYPE = "softmax"
13: SUPPORTED_PRECISIONS = ["fp32"]
14: HARDWARE_REQUIRED = ["RTX_PRO_6000", "H100", "B200"]
15: 
16: 
17: class Model(nn.Module):
18:     """y = softmax(x, dim=-1) computed in fp64 then returned as fp32.
19: 
20:     No learned parameters — softmax is parameter-free. We still expose an
21:     empty state_dict so the harness's strict load_state_dict matches.
22:     """
23: 
24:     def __init__(self, batch: int, vocab: int):
25:         super().__init__()
26:         self.batch = batch
27:         self.vocab = vocab
28: 
29:     def forward(self, x: torch.Tensor) -> torch.Tensor:
30:         # Promote to fp64 for the ground-truth pathway. Even with double
31:         # precision we still subtract the row-max for stability.
32:         x64 = x.to(torch.float64)
33:         m = x64.amax(dim=-1, keepdim=True)
34:         e = torch.exp

... (592 more chars)
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/check.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/check.py"
}
tool
stdout (4964 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/check.py</path>
<type>file</type>
<content>
1: """Correctness runner for Kahan-corrected softmax.
2: 
3: Runs solution.Model vs reference.Model across all shapes in shapes.py, 3
4: seeds each, with the tight (1e-5) fp32 tolerance from problem.yaml. Also
5: rejects forbidden ops via grep.
6: """
7: import re
8: import sys
9: from pathlib import Path
10: 
11: import torch
12: import yaml
13: 
14: # Make the repo's src/ importable
15: REPO_ROOT = Path(__file__).resolve().parents[2]
16: sys.path.insert(0, str(REPO_ROOT))
17: 
18: from src.eval.correctness import check_correctness  # noqa: E402
19: 
20: 
21: def _make_inputs(batch: int, vocab: int, extreme: bool, seed: int) -> torch.Tensor:
22:     g = torch.Generator().manual_seed(seed)
23:     if extreme:
24:         # Adversarial: most logits are mild but a handful per row are huge.
25:         # If the kernel forgets to subtract the row-max before exp, this
26:         # row overflows fp32 and produces NaN/Inf. If it accumulates in
27:         # fp16, the long tail of small exp() values is lost beneath the
28:         # tolerance threshold.
29:         x = torch.randn(batch, vocab, generator=g) * 2.0
30:         # Spike: 4 very large positive logits per row.
31:         idx = torch.randint(0, vocab, (batch, 4), generator=g)
32:         x.scatter_(1, idx, 30.0)
33:     else:
34:         x = torch.randn(batch, vocab, generator=g) * 4.0
35:     return x.to(torc

... (3464 more chars)
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/benchmark.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/benchmark.py"
}
tool
stdout (5206 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/benchmark.py</path>
<type>file</type>
<content>
1: """Roofline benchmark for Kahan-corrected softmax.
2: 
3: For each shape: times eager reference, compiled reference, SOTA (if
4: available), and the agent's solution. Reports achieved TFLOPS, GB/s, and
5: peak_fraction. Softmax is memory-bound, so the score is GB/s / peak_dram.
6: 
7: Output lines the harness picks up:
8:   shape=<idx> variant=<name> tflops=<N> gbps=<N> ms=<N>
9:   peak_fraction: <N>  (geomean over shapes of solution's peak_fraction)
10: """
11: import sys
12: from math import exp, log
13: from pathlib import Path
14: 
15: import torch
16: import yaml
17: 
18: REPO_ROOT = Path(__file__).resolve().parents[2]
19: sys.path.insert(0, str(REPO_ROOT))
20: 
21: from src.eval.roofline import compute_gbps, compute_tflops, peak_fraction  # noqa: E402
22: from src.eval.timing import time_fn  # noqa: E402
23: from src.hardware import get as get_hw  # noqa: E402
24: 
25: 
26: def _eval_formula(expr: str, vars: dict) -> float:
27:     return float(eval(expr, {"__builtins__": {}}, vars))
28: 
29: 
30: def _make_inputs(batch: int, vocab: int, extreme: bool) -> torch.Tensor:
31:     if extreme:
32:         x = torch.randn(batch, vocab) * 2.0
33:         idx = torch.randint(0, vocab, (batch, 4))
34:         x.scatter_(1, idx, 30.0)
35:     else:
36:         x = torch.randn(batch, vocab) * 4.0
37:     return x.to(torch.float32)
38: 
39: 
40: def main():
41:  

... (3706 more chars)
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/problem.yaml
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/problem.yaml"
}
tool
stdout (1725 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/problem.yaml</path>
<type>file</type>
<content>
1: name: 04_kahan_softmax
2: display_name: "Kahan-corrected Softmax"
3: precision: fp32
4: regime: memory  # softmax is bandwidth-bound: 2 passes over the input tensor
5: 
6: # Softmax FLOPs: per-element exp + 2 reductions + divide. Roughly 5 flops/elt.
7: flops_formula: "5 * batch * vocab"
8: 
9: # Bytes moved: read x once, write y once. Both fp32.
10: bytes_formula: "batch * vocab * 4 + batch * vocab * 4"
11: 
12: hardware: [RTX_PRO_6000]
13: peak_tflops_key: fp32
14: peak_bandwidth_key: dram
15: 
16: # TIGHTER than default (fp32 default is 1e-4). This problem exists
17: # specifically to test whether the agent uses compensated summation, so
18: # we squeeze the tolerance to 1e-5 — naive fp16 sum across 256K elements
19: # drifts past this; fp32 accumulation passes; Kahan/fp32 always passes.
20: tolerance:
21:   "torch.float32": {"atol": 1.0e-5, "rtol": 1.0e-5}
22: 
23: # Forbidden ops — block the obvious "just call the library" cheats. The
24: # agent must implement softmax themselves with explicit (compensated)
25: # summation logic.
26: forbidden:
27:   - "torch.nn.functional.softmax"
28:   - "torch.softmax"
29:   - "F.softmax"
30:   - "liger_kernel.softmax"
31:   - "liger_kernel.transformers.softmax"
32:   - ".softmax("
33: 
34: sota:
35:   name: "Liger-Kernel Softmax (Triton)"
36:   url: "https://github.com/linkedin/Liger-Kernel"
37:   function: "liger_

... (225 more chars)
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/shapes.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/shapes.py"
}
tool
stdout (1399 chars)
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/shapes.py</path>
<type>file</type>
<content>
1: """Shape sweep for Kahan-corrected softmax.
2: 
3: The point of this problem is numerical accuracy on long reductions. Shapes
4: mix typical LLM vocab sizes with deliberately adversarial regimes:
5: 
6:   - small vocab (sanity check; naive fp32 should pass)
7:   - Llama3 vocab 128K (real-world, where fp16 accumulation starts to drift)
8:   - 256K (DeepSeek-V3 / Gemma-3 class vocab; naive fp16 sum DOES drift past
9:     the 1e-5 tolerance — this row is what proves Kahan was needed)
10:   - extreme-logit edge case (large positive logits stress max-subtract +
11:     summation; if the implementation accidentally exps before subtracting
12:     max, this row overflows)
13: 
14: The 'extreme' flag is read by check.py to switch input generation to a
15: distribution that produces a few very large logits per row.
16: """
17: 
18: SHAPES = [
19:     {"batch": 32, "vocab": 4096, "extreme": False},      # sanity
20:     {"batch": 16, "vocab": 32768, "extreme": False},     # GPT-2 class
21:     {"batch": 8,  "vocab": 131072, "extreme": False},    # Llama3 vocab
22:     {"batch": 4,  "vocab": 262144, "extreme": False},    # 256K — Kahan needed
23:     {"batch": 8,  "vocab": 131072, "extreme": True},     # extreme logits edge
24: ]

(End of file - total 24 lines)
</content>
assistant
read /home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/sota.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/sota.py"
}
tool
stdout (1628 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/problems/04_kahan_softmax/sota.py</path>
<type>file</type>
<content>
1: """SOTA reference for last-dim softmax.
2: 
3: Preference order:
4:   1. liger-kernel's Triton softmax (LigerSoftmaxFunction) — fused, fp32-acc
5:   2. torch.compile(torch.softmax) — Inductor generates a Triton kernel that
6:      is competitive on bandwidth-bound reductions
7: 
8: Agents are FORBIDDEN from importing either of these in solution.py (see
9: problem.yaml.forbidden). This file is only the benchmark's reference line.
10: """
11: from __future__ import annotations
12: 
13: import torch
14: 
15: _compiled_softmax = None
16: 
17: 
18: def _liger_softmax(x: torch.Tensor) -> torch.Tensor | None:
19:     try:
20:         from liger_kernel.ops.softmax import LigerSoftmaxFunction
21:         return LigerSoftmaxFunction.apply(x)
22:     except Exception:
23:         return None
24: 
25: 
26: def _compiled(x: torch.Tensor) -> torch.Tensor:
27:     global _compiled_softmax
28:     if _compiled_softmax is None:
29:         _compiled_softmax = torch.compile(
30:             lambda t: torch.softmax(t, dim=-1),
31:             mode="reduce-overhead",
32:         )
33:     return _compiled_softmax(x)
34: 
35: 
36: def sota_forward(x: torch.Tensor) -> torch.Tensor:
37:     """Best-available softmax reference. x: (batch, vocab) fp32."""
38:     out = _liger_softmax(x)
39:     if out is not None:
40:         return out
41:     return _compiled(x)
42: 
43: 
44: def is_a

... (128 more chars)
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assistant
bash
args
{
  "command": "nvidia-smi --query-gpu=name,memory.total,compute_cap --format=csv,noheader 2>/dev/null | head -1",
  "description": "Check GPU info"
}
tool
stdout (67 chars)
NVIDIA RTX PRO 6000 Blackwell Workstation Edition, 97887 MiB, 12.0
assistant
bash
args
{
  "command": "python3 -c \"import triton; print(triton.__version__)\" 2>&1",
  "description": "Check triton version"
}
tool
stdout (6 chars)
3.6.0
assistant
Let me check the GPU and available tools, and look at how other solutions in this repo are structured.
assistant
bash
args
{
  "command": "python3 -c \"import torch; print(torch.version.cuda, torch.cuda.get_device_properties(0).major, torch.cuda.get_device_properties(0).minor)\" 2>&1",
  "description": "Check torch CUDA version"
}
tool
stdout (10 chars)
13.0 12 0
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glob
args
{
  "pattern": "problems/*/solution.py"
}
tool
stdout (14 chars)
No files found
assistant
read /home/infatoshi/cuda/KernelBench-Hard/src/eval/correctness.py
args
{
  "filePath": "/home/infatoshi/cuda/KernelBench-Hard/src/eval/correctness.py"
}
tool
stdout (4080 chars) — TRUNCATED
<path>/home/infatoshi/cuda/KernelBench-Hard/src/eval/correctness.py</path>
<type>file</type>
<content>
1: """Per-dtype correctness tolerance.
2: 
3: Stanford's KernelBench uses 1e-4 atol/rtol for fp32 and 1e-2 for fp16/bf16.
4: We extend to fp8 (0.1, permissive) and int (exact).
5: """
6: from __future__ import annotations
7: 
8: import torch
9: 
10: DEFAULT_TOLERANCE = {
11:     torch.float32: {"atol": 1e-4, "rtol": 1e-4},
12:     torch.float16: {"atol": 1e-2, "rtol": 1e-2},
13:     torch.bfloat16: {"atol": 1e-2, "rtol": 1e-2},
14:     torch.float8_e4m3fn: {"atol": 1e-1, "rtol": 1e-1},
15:     torch.float8_e5m2: {"atol": 1e-1, "rtol": 1e-1},
16:     torch.int8: {"atol": 0, "rtol": 0},
17:     torch.int32: {"atol": 0, "rtol": 0},
18:     torch.int64: {"atol": 0, "rtol": 0},
19: }
20: 
21: 
22: def _coerce_float(x):
23:     """Accept int/float/str scientific-notation as float; pass through dicts."""
24:     if isinstance(x, (int, float)):
25:         return float(x)
26:     if isinstance(x, str):
27:         try:
28:             return float(x)
29:         except ValueError:
30:             return x
31:     return x
32: 
33: 
34: def tolerance_for_dtype(dtype: torch.dtype, override: dict | None = None) -> dict:
35:     """Lookup atol/rtol for a given dtype, with optional per-problem override.
36: 
37:     The override dict is keyed by str(dtype). Values may be:
38:       - a single number (or a string parseable as float, e.g. "5e-2") -> used
39:         as both atol and rtol
4

... (2580 more chars)
assistant
Let me look at a similar existing solution for patterns.
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in 20325out 89cache_r 0cache_w 0
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in 0out 0cache_r 0cache_w 0