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80692f2 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 | name: 04_kahan_softmax
display_name: "Kahan-corrected Softmax"
precision: fp32
regime: memory # softmax is bandwidth-bound: 2 passes over the input tensor
# Softmax FLOPs: per-element exp + 2 reductions + divide. Roughly 5 flops/elt.
flops_formula: "5 * batch * vocab"
# Bytes moved: read x once, write y once. Both fp32.
bytes_formula: "batch * vocab * 4 + batch * vocab * 4"
hardware: [RTX_PRO_6000]
peak_tflops_key: fp32
peak_bandwidth_key: dram
# TIGHTER than default (fp32 default is 1e-4). This problem exists
# specifically to test whether the agent uses compensated summation, so
# we squeeze the tolerance to 1e-5 — naive fp16 sum across 256K elements
# drifts past this; fp32 accumulation passes; Kahan/fp32 always passes.
tolerance:
"torch.float32": {"atol": 1.0e-5, "rtol": 1.0e-5}
# Forbidden ops — block the obvious "just call the library" cheats. The
# agent must implement softmax themselves with explicit (compensated)
# summation logic.
forbidden:
- "torch.nn.functional.softmax"
- "torch.softmax"
- "F.softmax"
- "liger_kernel.softmax"
- "liger_kernel.transformers.softmax"
- ".softmax("
sota:
name: "Liger-Kernel Softmax (Triton)"
url: "https://github.com/linkedin/Liger-Kernel"
function: "liger_kernel.ops.softmax.LigerSoftmaxFunction"
deps:
- "liger-kernel>=0.5.0"
reference_throughput_gbps_h100: 2800
num_correct_trials: 3
num_perf_trials: 30
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