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sglang/test/manual/dsv4/test_wo_a_fp8_sm90.py

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"""Manual correctness check for DeepSeek-V4 fp8 wo_a (deep_gemm.fp8_einsum path).
Mirrors models/deepseek_v4.py MQALayer wo_a: quantize the token-major attention
output [T, G, D] per-token-group(128) to fp8, then run the grouped matmul over the
group/head dim via deep_gemm.fp8_einsum("bhr,hdr->bhd") -> [T, G, R], and compare
against a bf16 einsum reference. sm100 (Blackwell) uses ue8m0 scales + recipe
(1,1,128); sm90 (Hopper) uses fp32 scales + recipe (1,128,128). Covers the Flash
(G=8) and Pro (G=16) shapes for both prefill (T=1024) and decode (small T).
CUDA_VISIBLE_DEVICES=0 python3 test/manual/dsv4/test_wo_a_fp8_sm90.py
"""
from __future__ import annotations
import argparse
from dataclasses import dataclass
import torch
import torch.nn.functional as F
from sglang.srt.layers import deep_gemm_wrapper
@dataclass(frozen=True)
class WoACase:
name: str
groups: int
tokens: int
k: int = 4096
n: int = 1024
def cosine(a: torch.Tensor, b: torch.Tensor) -> float:
return F.cosine_similarity(a.float().flatten(), b.float().flatten(), dim=0).item()
def quantize_weight_by_group(
weight: torch.Tensor,
) -> tuple[torch.Tensor, torch.Tensor]:
"""Per-block (128x128) fp8 cast of the per-group wo_a weight [G, N, K]."""
from deep_gemm.utils import per_block_cast_to_fp8
groups, n, k = weight.shape
weight_fp8 = torch.empty_like(weight, dtype=torch.float8_e4m3fn)
weight_scale = torch.empty(
(groups, n // 128, k // 128), device=weight.device, dtype=torch.float32
)
for group in range(groups):
weight_fp8[group], weight_scale[group] = per_block_cast_to_fp8(
weight[group], use_ue8m0=False, gran_k=128
)
return weight_fp8, weight_scale
def run_wo_a_einsum(
o: torch.Tensor, # [T, G, D] bf16
weight_fp8: torch.Tensor, # [G, N, K] fp8
weight_scale: torch.Tensor, # [G, N/128, K/128] fp32
) -> torch.Tensor:
"""Mirror models/deepseek_v4.py MQALayer wo_a fp8 einsum path."""
import deep_gemm
from sglang.kernels.ops.quantization.fp8_kernel import (
sglang_per_token_group_quant_fp8,
)
T, G, D = o.shape
_, R, _ = weight_fp8.shape
o_fp8, o_s = sglang_per_token_group_quant_fp8(
o.reshape(T * G, D).contiguous(),
group_size=128,
)
recipe = (1, 128, 128)
output = torch.empty(T, G, R, device=o.device, dtype=torch.bfloat16)
deep_gemm.fp8_einsum(
"bhr,hdr->bhd",
(o_fp8.view(T, G, D), o_s.view(T, G, -1)),
(weight_fp8, weight_scale),
output,
recipe=recipe,
)
return output
def check(case: WoACase, args: argparse.Namespace) -> None:
device = torch.device(args.device)
torch.manual_seed(args.seed)
o = (
torch.randn(
case.tokens, case.groups, case.k, device=device, dtype=torch.bfloat16
)
* 0.1
)
weight = (
torch.randn(case.groups, case.n, case.k, device=device, dtype=torch.bfloat16)
* 0.05
)
weight_fp8, weight_scale = quantize_weight_by_group(weight)
out = run_wo_a_einsum(o, weight_fp8, weight_scale)
bf16_ref = torch.einsum("tgd,grd->tgr", o.float(), weight.float()).to(
torch.bfloat16
)
torch.cuda.synchronize()
cb = cosine(out, bf16_ref)
print(f"{case.name}: G={case.groups} T={case.tokens} cos_bf16={cb:.6f}")
if cb <= args.cos_gate:
raise AssertionError(f"{case.name} cos_bf16 {cb} <= {args.cos_gate}")
def main() -> None:
parser = argparse.ArgumentParser()
parser.add_argument("--device", default="cuda")
parser.add_argument("--seed", type=int, default=0)
parser.add_argument("--cos-gate", type=float, default=0.999)
parser.add_argument("--decode-tokens", type=int, default=16)
args = parser.parse_args()
if deep_gemm_wrapper.DEEPGEMM_SCALE_UE8M0:
print(
"SKIP: this manual test validates the sm90 fp32-scale wo_a einsum path; "
"the sm100/Blackwell production path uses ue8m0 scales + a weight-scale "
"transform not reproduced here."
)
return
cases = [
WoACase("flash prefill", groups=8, tokens=1024),
WoACase("flash decode", groups=8, tokens=args.decode_tokens),
WoACase("pro prefill", groups=16, tokens=1024),
WoACase("pro decode", groups=16, tokens=args.decode_tokens),
]
for case in cases:
check(case, args)
print("ALL OK")
if __name__ == "__main__":
main()