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cublaslt_fp4_e2m1_scaled_mm_n4096_k2048

FlashInfer-Bench baselines · python · Apache-2.0

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Vendorable · source mirrored · Apache-2.0View source →

No package. Vendor the mirrored source: 19 lines, Apache-2.0, pinned at da91508.

main.py
curl "https://kernelindex.com/api/v1/implementations/flashinfer-cublaslt-fp4-e2m1-scaled-mm-n4096-k2048?include=source"
interfacepython
revisionda915083d4c7
symbolrun
pathmain.py
Compatibility
measured onNVIDIA B200
declared hardwareNVIDIA B200
architecturessm_100
dtypesint8

Benchmark evidence

3 measurements across 1 GPU, fastest first.

Operation / workload
Hardware
Latency
Rank
Observed
GEMM fp4 e2m1 n4096 k2048int8 · [128, 1024]
NVIDIA B200
47.9µs
#1 of 1
2026-06-06
GEMM fp4 e2m1 n4096 k2048int8 · [1024, 1024]
NVIDIA B200
56.4µs
#1 of 1
2026-06-06
GEMM fp4 e2m1 n4096 k2048int8 · [256, 1024]
NVIDIA B200
56.5µs
#1 of 1
2026-06-06

Reported · How evidence levels are derived →

Source and license

sourcehttps://huggingface.co/datasets/flashinfer-ai/flashinfer-trace
commitda915083d4c7c5e61aa3005e3d17ae488e0fc71c
revision digestsha256:ea6b49b7f81bfbd432e22570f1e9b2a0eee9e25b4300a14fcd293ea10e93b67a
license declaredApache-2.0
license concludedApache-2.0
authorsbaseline
imported2026-08-16

Kernel source

main.py19 lines
import torch
from torchao.prototype.mx_formats.utils import to_blocked


def run(A_fp4, B_fp4):
    # cuBLASLt unscaled FP4 GEMM via torch._scaled_mm with all-ones (1.0) block scales.
    m = A_fp4.shape[0]
    k = A_fp4.shape[1] * 2
    n = B_fp4.shape[0]
    dev = A_fp4.device
    a_blk = to_blocked(torch.ones(m, k // 16, device=dev, dtype=torch.float8_e4m3fn))
    b_blk = to_blocked(torch.ones(n, k // 16, device=dev, dtype=torch.float8_e4m3fn))
    out = torch._scaled_mm(
        A_fp4.view(torch.float4_e2m1fn_x2),
        B_fp4.view(torch.float4_e2m1fn_x2).T,
        a_blk, b_blk, out_dtype=torch.bfloat16,
    )
    return out

Source code from FlashInfer-Bench (flashinfer-ai/flashinfer-trace) · Apache-2.0

Best evidence level for this revision: reported

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