vllm/tests/kernels/moe/test_cutedsl_moe.py
Shu Wang 613abb50d5
[MoE] Nvfp4 Masked Gemm: Add flashinfer grouped_gemm_nt_masked (#25990)
Signed-off-by: Shu Wang. <shuw@nvidia.com>
Signed-off-by: mgoin <mgoin64@gmail.com>
Co-authored-by: Michael Goin <mgoin64@gmail.com>
2025-11-19 13:29:06 -08:00

583 lines
18 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import pytest
from vllm.platforms import current_platform
if not current_platform.has_device_capability(100):
pytest.skip(
reason="Nvfp4 Requires compute capability of 10 or above.",
allow_module_level=True,
)
import torch
from flashinfer import fp4_quantize
from torch.nn import functional as F
from vllm.model_executor.layers.activation import SiluAndMul
from vllm.model_executor.layers.fused_moe.flashinfer_cutedsl_moe import (
flashinfer_cutedsl_moe_masked,
)
from vllm.utils.flashinfer import (
flashinfer_cutedsl_grouped_gemm_nt_masked as cutedsl_gmm_masked,
)
from vllm.utils.flashinfer import (
scaled_fp4_grouped_quantize,
)
kE2M1ToFloat = torch.tensor(
[0.0, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0], dtype=torch.float32
)
FLOAT8_E4M3_MAX = 448.0
FLOAT4_E2M1_MAX = 6.0
def convert_swizzled_to_linear(a_sf_swizzled: torch.Tensor, m, k, block_size):
m_tiles = (m + 128 - 1) // 128
f = block_size * 4
k_tiles = (k + f - 1) // f
tmp = torch.reshape(a_sf_swizzled, (1, m_tiles, k_tiles, 32, 4, 4))
tmp = torch.permute(tmp, (0, 1, 4, 3, 2, 5))
out = tmp.reshape(m_tiles * 128, k_tiles * f // block_size)
return out[0:m, 0:k]
def dequantize_nvfp4_to_dtype(
tensor_fp4, tensor_sf, global_scale, dtype, device, block_size=16
):
"""Dequantize the fp4 tensor back to high precision."""
# Two fp4 values are packed into one uint8.
assert tensor_fp4.dtype == torch.uint8
m, packed_k = tensor_fp4.shape
k = packed_k * 2
tensor_f32 = break_fp4_bytes(tensor_fp4, dtype)
tensor_f32 = tensor_f32.reshape(m, k // block_size, block_size)
tensor_sf = tensor_sf.view(torch.float8_e4m3fn)
tensor_sf = convert_swizzled_to_linear(tensor_sf, m, k, block_size)
tensor_sf_dtype = tensor_sf.to(torch.float32) / global_scale
# scale the tensor
out = (tensor_f32 * tensor_sf_dtype.unsqueeze(-1)).reshape(m, k)
return out.to(dtype=dtype)
def break_fp4_bytes(a, dtype):
assert a.dtype == torch.uint8
m, n = a.shape
# Vectorized nibble processing
a_flat = a.flatten()
high = (a_flat & 0xF0) >> 4 # Upper nibbles
low = a_flat & 0x0F # Lower nibbles
# Combine nibbles for batch processing
combined = torch.stack((low, high), dim=1).flatten()
# Vectorized sign and magnitude extraction
signs = (combined & 0x08).to(torch.bool) # Sign bits
abs_vals = (combined & 0x07).to(torch.long) # Magnitude indices
# Device-aware lookup and sign application
kE2M1 = kE2M1ToFloat.to(device=a.device)
values = kE2M1[abs_vals] * torch.where(signs, -1.0, 1.0)
# Reshape to final form
return values.reshape(m, n * 2).to(dtype=dtype)
def generate_balanced_routing(
hidden_states: torch.Tensor, num_experts: int, top_k: int
):
"""
Generate routing weights and topk indices such that every expert is active.
Returns routing_weights, topk_idx
"""
num_tokens, hidden_dim = hidden_states.shape
# num_tokens = batch_size * seq_len
# First, assign at least one token per expert
tokens_per_expert = torch.arange(num_tokens) % num_experts
tokens_per_expert = tokens_per_expert[torch.randperm(num_tokens)] # shuffle
# Each token has top_k experts — start with one guaranteed expert
topk_idx = torch.full((num_tokens, top_k), -1, dtype=torch.long)
topk_idx[:, 0] = tokens_per_expert
# For remaining top_k - 1 experts, pick randomly (allowing repeats)
if top_k > 1:
random_choices = torch.randint(0, num_experts, (num_tokens, top_k - 1))
topk_idx[:, 1:] = random_choices
# Normalize routing weights so each token's weights sum to 1
routing_weights = torch.rand(num_tokens, top_k)
routing_weights /= routing_weights.sum(dim=-1, keepdim=True)
# Reshape back if needed
routing_weights = routing_weights.view(num_tokens, top_k)
topk_idx = topk_idx.view(num_tokens, top_k)
return routing_weights, topk_idx
def prepare_inputs(
hidden_states: torch.Tensor,
router_logits: torch.Tensor,
num_experts: int,
topk: int,
):
routing_weights, topk_idx = generate_balanced_routing(
router_logits, num_experts, topk
)
masked_m = []
for i in range(num_experts):
mask = topk_idx.view(-1) == i
masked_m.append(mask.sum())
masked_m = torch.tensor(masked_m, dtype=torch.int32)
# Intialize the hidden_states_3d with ones instead of empty to avoid nan
# issue.
hidden_states_3d = torch.ones(
(num_experts, max(masked_m), hidden_states.shape[1]), dtype=hidden_states.dtype
)
for i in range(num_experts):
hidden_states_3d[i, : masked_m[i], :] = hidden_states[topk_idx.view(-1) == i]
return hidden_states_3d, masked_m, topk_idx, routing_weights
MNK_FACTORS = [
(2, 1024, 1024),
(2, 1024, 1536),
(2, 3072, 1024),
(2, 3072, 1536),
(64, 1024, 1024),
(64, 1024, 1536),
(64, 3072, 1024),
(64, 2048, 1024),
(224, 1024, 1024),
(224, 1024, 1536),
]
# Reference implementation of torch_moe
def torch_moe(a, w1, w2, score, topk, expert_map):
B, D = a.shape
a = a.view(B, -1, D).repeat(1, topk, 1).reshape(-1, D)
out = torch.zeros(B * topk, w2.shape[1], dtype=a.dtype, device=a.device)
score = torch.softmax(score, dim=-1, dtype=torch.float32)
topk_weight, topk_ids = torch.topk(score, topk)
topk_weight = topk_weight.view(-1)
topk_ids = topk_ids.view(-1)
if expert_map is not None:
topk_ids = expert_map[topk_ids]
for i in range(w1.shape[0]):
mask = topk_ids == i
if mask.sum():
out[mask] = SiluAndMul()(a[mask] @ w1[i].transpose(0, 1)) @ w2[i].transpose(
0, 1
)
return (
out.view(B, -1, w2.shape[1]) * topk_weight.view(B, -1, 1).to(out.dtype)
).sum(dim=1)
def torch_moe_nvfp4(a, w1, w2, topk, topk_weight, topk_ids):
B, D = a.shape
a = a.view(B, -1, D).repeat(1, topk, 1).reshape(-1, D)
out = torch.zeros(B * topk, w2.shape[1], dtype=a.dtype, device=a.device)
topk_weight = topk_weight.view(-1)
topk_ids = topk_ids.view(-1)
for i in range(w1.shape[0]):
mask = topk_ids == i
if mask.sum():
m = w1[i].shape[0]
assert m % 2 == 0
# Note: w1 and w3 are swapped!
w3_expert, w1_expert = w1[i][m // 2 :, :], w1[i][: m // 2, :]
inter = F.silu(a[mask] @ w1_expert.t()) * (a[mask] @ w3_expert.t())
inter_gs = torch.tensor(1.0).cuda()
inter_q, inter_blockscale = fp4_quantize(inter, inter_gs)
inter = dequantize_nvfp4_to_dtype(
inter_q,
inter_blockscale,
inter_gs,
dtype=inter.dtype,
device=inter.device,
block_size=16,
).cuda()
out[mask] = inter @ w2[i].transpose(0, 1)
return (
out.view(B, -1, w2.shape[1]) * topk_weight.view(B, -1, 1).to(out.dtype)
).sum(dim=1)
def grouped_gemm_ref(
hidden_states_expanded: torch.Tensor,
hidden_states_3d: torch.Tensor,
weights: torch.Tensor,
topk_idx: torch.Tensor,
masked_m: torch.Tensor,
B: int,
topk: int,
num_experts: int,
*,
block_size: int = 16,
) -> torch.Tensor:
"""
Computes the reference grouped GEMM (fp4 quantized per-expert loop),
computes flashinfer grouped GEMM (for scale consistency),
and returns ONLY the repacked reference output: out_ref.
Returns:
out_ref: Tensor [num_experts, max_m, n_out]
"""
device_hs = hidden_states_expanded.device
device_w = weights.device
out_dtype = weights.dtype
n_out = weights.shape[1]
# Flattened reference output (B*topk, n_out)
out = torch.zeros((B * topk, n_out), dtype=out_dtype, device=device_w)
# Per-expert reference compute loop
for i in range(num_experts):
mask = topk_idx.view(-1) == i
if mask.any():
lhs = hidden_states_expanded[mask]
rhs = weights[i]
a_amax = lhs.abs().max().to(torch.float32).to(device_hs)
b_amax = rhs.abs().max().to(torch.float32).to(device_w)
a_gs = FLOAT8_E4M3_MAX * FLOAT4_E2M1_MAX / a_amax
b_gs = FLOAT8_E4M3_MAX * FLOAT4_E2M1_MAX / b_amax
lhsq, lhsq_sf = fp4_quantize(lhs, a_gs)
rhsq, rhsq_sf = fp4_quantize(rhs, b_gs)
lhs_in_dtype = dequantize_nvfp4_to_dtype(
lhsq,
lhsq_sf,
a_gs,
dtype=lhs.dtype,
device=device_hs,
block_size=block_size,
)
rhs_in_dtype = dequantize_nvfp4_to_dtype(
rhsq,
rhsq_sf,
b_gs,
dtype=rhs.dtype,
device=device_w,
block_size=block_size,
)
out[mask] = lhs_in_dtype @ rhs_in_dtype.t()
# Determine per-expert max_m
max_m_val = int(masked_m.max().item())
# Repack into [num_experts, max_m, n_out]
out_ref = torch.zeros(
(num_experts, max_m_val, n_out),
dtype=out.dtype,
device=out.device,
)
expert_slot = [0] * num_experts
for i, expert_id in enumerate(topk_idx.view(-1).tolist()):
slot = expert_slot[expert_id]
if slot < max_m_val:
out_ref[expert_id, slot, :] = out[i]
expert_slot[expert_id] += 1
else:
raise IndexError(
f"Expert {expert_id} exceeded max slots ({max_m_val}). "
"Increase max_m or check masked_m."
)
return out_ref
def flashinfer_cutedsl_grouped_gemm_nt_masked(
hidden_states: torch.Tensor, # 3d
input_global_scale: torch.Tensor, # (l,)
weights: torch.Tensor,
w_global_scale: torch.Tensor, # (l,)
masked_m: torch.Tensor,
):
# hidden_states: [l, m, k]
# weights: [l, n, k]
aq, aq_sf = scaled_fp4_grouped_quantize(
hidden_states,
masked_m.to(hidden_states.device),
input_global_scale,
)
num_experts, n, k = weights.shape
bq, bq_sf = scaled_fp4_grouped_quantize(
weights,
torch.full((num_experts,), n, device=weights.device, dtype=torch.int32),
w_global_scale,
)
out = torch.zeros(
(num_experts, max(masked_m), n), dtype=weights.dtype, device=aq.device
)
out = out.permute(1, 2, 0) # requirement of kernel
sf_vec_size = 16
ab_dtype = "float4_e2m1fn"
sf_dtype = "float8_e4m3fn"
c_dtype = "bfloat16"
alpha = 1.0 / (input_global_scale * w_global_scale).to(out.dtype).view(
1, 1, num_experts
)
def get_cute_dtype(input: torch.Tensor) -> str:
if input.dtype == torch.bfloat16:
return "bfloat16"
elif input.dtype == torch.float16:
return "float16"
elif input.dtype == torch.float32:
return "float32"
else:
raise ValueError(f"Unsupported cute dtype {input.dtype}")
cutedsl_gmm_masked(
(aq, aq_sf),
(bq, bq_sf),
out,
masked_m.to(aq.device),
ab_dtype=ab_dtype,
sf_dtype=sf_dtype,
c_dtype=c_dtype,
sf_vec_size=sf_vec_size,
alpha=alpha,
alpha_dtype=get_cute_dtype(alpha),
)
return out
@pytest.mark.parametrize("bs, hidden_dim, inter_dim", [(2, 128, 256), (16, 128, 512)])
@pytest.mark.parametrize("topk", [1, 2, 4])
@torch.inference_mode()
def test_flashinfer_cutedsl_moe_masked(
bs: int, hidden_dim: int, inter_dim: int, topk: int
):
torch.manual_seed(42)
device = "cuda"
num_experts = 8
hidden_states = (
torch.randn(bs, hidden_dim, dtype=torch.bfloat16, device=device) / 5.0
)
w1 = (
torch.randn(
num_experts, 2 * inter_dim, hidden_dim, dtype=torch.bfloat16, device=device
)
/ 10.0
)
w2 = (
torch.randn(
num_experts, hidden_dim, inter_dim, dtype=torch.bfloat16, device=device
)
/ 10.0
)
router_logits = torch.randn(bs, num_experts, dtype=torch.float32)
hidden_states_expanded = (
hidden_states.view(bs, -1, hidden_dim)
.repeat(1, topk, 1)
.reshape(-1, hidden_dim)
)
hidden_states_3d, masked_m, topk_idx, routing_weights = prepare_inputs(
hidden_states_expanded, router_logits, num_experts, topk
)
w1_amax = w1.abs().amax(dim=(1, 2)).to(torch.float32).to(w1.device)
w2_amax = w2.abs().amax(dim=(1, 2)).to(torch.float32).to(w2.device)
input_global_scale = torch.ones(
(num_experts,), dtype=torch.float32, device=hidden_states.device
)
w1_global_scale = FLOAT8_E4M3_MAX * FLOAT4_E2M1_MAX / w1_amax
w2_global_scale = FLOAT8_E4M3_MAX * FLOAT4_E2M1_MAX / w2_amax
a2_global_scale = torch.ones(
(num_experts,), dtype=torch.float32, device=hidden_states.device
) # assume intermediate scale is 1.0
w1_fp4, w1_blockscale = scaled_fp4_grouped_quantize(
w1,
torch.ones(num_experts, dtype=torch.int32, device=w1.device) * 2 * inter_dim,
w1_global_scale,
)
w2_fp4, w2_blockscale = scaled_fp4_grouped_quantize(
w2,
torch.ones(num_experts, dtype=torch.int32, device=w2.device) * hidden_dim,
w2_global_scale,
)
w1_alpha = 1.0 / (input_global_scale * w1_global_scale)
w2_alpha = 1.0 / (a2_global_scale * w2_global_scale)
out = torch.empty_like(hidden_states_3d)
# Note: the 1st dim shouldn't be bs
wk = torch.empty(
num_experts,
hidden_states_3d.shape[1],
inter_dim * 2,
dtype=hidden_states_3d.dtype,
device=hidden_states.device,
)
flashinfer_cutedsl_moe_masked(
hidden_states_3d.to(hidden_states.device),
input_global_scale,
w1_fp4.permute(2, 0, 1),
w1_blockscale,
w1_alpha,
w2_fp4.permute(2, 0, 1),
a2_global_scale,
w2_blockscale,
w2_alpha,
masked_m.to(hidden_states.device),
wk,
out,
)
# reference
a_fp4, a_scale_interleaved = fp4_quantize(hidden_states, input_global_scale)
a_in_dtype = dequantize_nvfp4_to_dtype(
a_fp4,
a_scale_interleaved,
input_global_scale,
dtype=hidden_states.dtype,
device=hidden_states.device,
block_size=16,
)
w1_d = torch.empty(
(num_experts, 2 * inter_dim, hidden_dim), device=w1.device, dtype=w1.dtype
)
w2_d = torch.empty(
(num_experts, hidden_dim, inter_dim), device=w2.device, dtype=w2.dtype
)
for idx in range(0, num_experts):
w1_fp4_sliced, w1_blockscale_sliced = fp4_quantize(
w1[idx], w1_global_scale[idx]
)
w2_fp4_sliced, w2_blockscale_sliced = fp4_quantize(
w2[idx], w2_global_scale[idx]
)
w1_d[idx] = dequantize_nvfp4_to_dtype(
w1_fp4_sliced,
w1_blockscale_sliced,
w1_global_scale[idx],
dtype=w1.dtype,
device=w1.device,
block_size=16,
)
w2_d[idx] = dequantize_nvfp4_to_dtype(
w2_fp4_sliced,
w2_blockscale_sliced,
w2_global_scale[idx],
dtype=w2.dtype,
device=w2.device,
block_size=16,
)
ref_output = torch_moe_nvfp4(
a_in_dtype,
w1_d,
w2_d,
topk,
routing_weights.to(a_in_dtype.device),
topk_idx.to(a_in_dtype.device),
)
out_weighted = torch.zeros_like(ref_output, device=out.device, dtype=out.dtype)
positions = torch.nonzero(masked_m[topk_idx], as_tuple=False)
rows, cols = positions[:, 0], positions[:, 1]
experts = topk_idx[rows, cols]
for i in range(num_experts):
mask = experts == i
if mask.any():
idx = torch.nonzero(mask, as_tuple=False).squeeze(-1)
r, c = rows[idx], cols[idx]
out_weighted[r] += out[i, : len(r), :] * routing_weights[r, c].to(
out.device
).unsqueeze(-1)
torch.testing.assert_close(
out_weighted.cpu(), ref_output.cpu(), atol=2e-1, rtol=2e-1
)
@pytest.mark.parametrize(
"bs, hidden_dim, inter_dim, topk", [(2, 128, 256, 2), (16, 128, 512, 5)]
)
@torch.inference_mode()
def test_grouped_gemm_nt_masked(
bs: int, hidden_dim: int, inter_dim: int, topk: int
) -> None:
torch.manual_seed(42)
B = bs
D = hidden_dim
N = inter_dim
# CuteDSL group gemm has issue when not all experts are active.
# i.e. masked = [2, 3, 0, 0, 1] where the 2nd and 3rd experts are inactive
# see https://github.com/flashinfer-ai/flashinfer/issues/1856
num_experts = bs
hidden_states = torch.randn(B, D, dtype=torch.bfloat16, device="cuda")
weights = torch.randn(num_experts, N, D, dtype=torch.bfloat16, device="cuda")
router_logits = torch.randn(B, num_experts, dtype=torch.float32)
hidden_states_expanded = (
hidden_states.view(B, -1, D).repeat(1, topk, 1).reshape(-1, D)
)
hidden_states_3d, masked_m, topk_idx, _ = prepare_inputs(
hidden_states_expanded, router_logits, num_experts, topk
)
a_amax = (
hidden_states_3d.abs()
.amax(dim=(1, 2))
.to(torch.float32)
.to(hidden_states.device)
)
b_amax = weights.abs().amax(dim=(1, 2)).to(torch.float32).to(weights.device)
a_gs = FLOAT8_E4M3_MAX * FLOAT4_E2M1_MAX / a_amax
b_gs = FLOAT8_E4M3_MAX * FLOAT4_E2M1_MAX / b_amax
out_flashinfer = flashinfer_cutedsl_grouped_gemm_nt_masked(
hidden_states_3d.to(hidden_states.device), a_gs, weights, b_gs, masked_m
)
# reference
out_ref = grouped_gemm_ref(
hidden_states_expanded=hidden_states_expanded,
hidden_states_3d=hidden_states_3d,
weights=weights,
topk_idx=topk_idx,
masked_m=masked_m,
B=B,
topk=topk,
num_experts=num_experts,
)
# Note: just to compare the masked position due to cutedsl may write nan
# into unmasked position.
for i in range(num_experts):
torch.testing.assert_close(
out_flashinfer.permute(2, 0, 1)[i, : masked_m[i]],
out_ref.to(out_flashinfer.device)[i, : masked_m[i]],
atol=1e-1,
rtol=1e-1,
)
if __name__ == "__main__":
test_flashinfer_cutedsl_moe_masked(16, 128, 512, 4)
test_grouped_gemm_nt_masked(16, 128, 512, 4)