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vllm-dev/vllm/model_executor/layers/quantization/utils/flashinfer_utils.py

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Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from enum import Enum
from typing import Optional
import torch
import vllm.model_executor.layers.fused_moe.modular_kernel as mk
from vllm import envs
from vllm.logger import init_logger
from vllm.model_executor.layers.fused_moe.config import FusedMoEConfig
from vllm.model_executor.layers.fused_moe.flashinfer_cutlass_moe import (
FlashInferExperts)
from vllm.model_executor.layers.fused_moe.flashinfer_cutlass_prepare_finalize import ( # noqa: E501
FlashInferCutlassMoEPrepareAndFinalize)
logger = init_logger(__name__)
class FlashinferMoeBackend(Enum):
TENSORRT_LLM = "TensorRT-LLM"
CUTLASS = "CUTLASS"
def calculate_tile_tokens_dim(num_tokens, top_k, num_experts):
# FlashInfer 0.2.10 has issues with larger tile sizes. Set to 8 for now.
# TODO: Revert this to dynamic calculation once a new version of FlashInfer
# with the necessary kernels is released.
tile_tokens_dim = 8
# from flashinfer import next_positive_power_of_2
# # Guess tokens per expert assuming perfect expert distribution first.
# num_tokens_per_expert = (num_tokens * top_k) // num_experts
# # And pad the number to the next power of 2.
# tile_tokens_dim = next_positive_power_of_2(num_tokens_per_expert)
# # Cap to 8-64 tokens per CTA tile as it's the range supported by the
# # kernel.
# tile_tokens_dim = min(max(tile_tokens_dim, 8), 64)
return tile_tokens_dim
def swap_w13_to_w31(x: torch.Tensor) -> torch.Tensor:
return x.reshape(-1, 2, x.shape[-2] // 2,
x.shape[-1]).flip(dims=[1]).reshape(x.shape)
def rotate_flashinfer_fp8_moe_weights(gemm1_weights: torch.Tensor,
gemm2_weights: torch.Tensor):
from flashinfer import reorder_rows_for_gated_act_gemm, shuffle_matrix_a
epilogue_tile_m = 128
num_experts = gemm1_weights.shape[0]
hidden_size = gemm1_weights.shape[-1]
intermediate_size = gemm1_weights.shape[1] // 2
# Reorder rows of W1 for fused gated activation
gemm1_weights_fp8_interleaved = []
for i in range(num_experts):
gemm1_weights_fp8_interleaved.append(
reorder_rows_for_gated_act_gemm(gemm1_weights[i]))
# Stack weights and scales for all experts
gemm1_weights_fp8_interleaved = torch.stack(
gemm1_weights_fp8_interleaved).reshape(num_experts,
2 * intermediate_size,
hidden_size)
# Shuffle weights and scaling factors for transposed mma output
gemm1_weights_fp8_shuffled = []
gemm2_weights_fp8_shuffled = []
for i in range(num_experts):
gemm1_weights_fp8_shuffled.append(
shuffle_matrix_a(
gemm1_weights_fp8_interleaved[i].view(torch.uint8),
epilogue_tile_m))
gemm2_weights_fp8_shuffled.append(
shuffle_matrix_a(gemm2_weights[i].view(torch.uint8),
epilogue_tile_m))
# Stack weights for all experts
gemm1_weights.data = torch.stack(gemm1_weights_fp8_shuffled).view(
torch.float8_e4m3fn)
gemm2_weights.data = torch.stack(gemm2_weights_fp8_shuffled).view(
torch.float8_e4m3fn)
def apply_flashinfer_per_tensor_scale_fp8(
layer: torch.nn.Module,
hidden_states: torch.Tensor,
router_logits: torch.Tensor,
routing_bias: Optional[torch.Tensor],
top_k: int,
num_expert_group: Optional[int],
topk_group: Optional[int],
global_num_experts: int,
apply_router_weight_on_input: bool,
) -> torch.Tensor:
from flashinfer.fused_moe import RoutingMethodType
assert layer.output1_scales_scalar is not None, (
"Expected output1_scales_scalar to be initialized")
assert layer.output1_scales_scalar is not None, (
"Expected output1_scales_gate_scalar to be initialized")
assert layer.output1_scales_scalar is not None, (
"Expected output2_scales_scalar to be initialized")
from vllm.model_executor.models.llama4 import Llama4MoE
assert layer.custom_routing_function == Llama4MoE.custom_routing_function, \
"FusedMoE flashinfer kernels are only supported for Llama4"
return torch.ops.vllm.flashinfer_fused_moe_per_tensor_scale_fp8(
routing_logits=router_logits,
routing_bias=routing_bias,
hidden_states=hidden_states,
input_scale=layer.w13_input_scale,
gemm1_weights=layer.w13_weight,
gemm2_weights=layer.w2_weight,
output1_scales_scalar=layer.output1_scales_scalar,
output1_scales_gate_scalar=layer.output1_scales_gate_scalar,
output2_scales_scalar=layer.output2_scales_scalar,
num_experts=global_num_experts,
top_k=top_k,
num_expert_group=num_expert_group,
topk_group=topk_group,
intermediate_size=layer.intermediate_size_per_partition,
local_expert_offset=layer.ep_rank * layer.local_num_experts,
local_num_experts=layer.local_num_experts,
use_routing_scales_on_input=apply_router_weight_on_input,
routing_method_type=RoutingMethodType.Llama4,
)
def get_moe_scaling_factors(
input_scale: torch.Tensor,
gemm1_weights_scale: torch.Tensor,
activation_scale: torch.Tensor,
gemm2_weights_scale: torch.Tensor,
) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
output1_scales_scalar = gemm1_weights_scale * input_scale * (
1.0 / activation_scale)
output1_scales_gate_scalar = gemm1_weights_scale * input_scale
output2_scales_scalar = activation_scale * gemm2_weights_scale
return output1_scales_scalar, output1_scales_gate_scalar, \
output2_scales_scalar
def register_moe_scaling_factors(layer: torch.nn.Module) -> None:
output1_scales, output1_gate_scales, output2_scales = \
get_moe_scaling_factors(
layer.w13_input_scale, layer.w13_weight_scale,
layer.w2_input_scale, layer.w2_weight_scale
)
layer.register_parameter(
'output1_scales_scalar',
torch.nn.Parameter(output1_scales, requires_grad=False))
layer.register_parameter(
'output1_scales_gate_scalar',
torch.nn.Parameter(output1_gate_scales, requires_grad=False))
layer.register_parameter(
'output2_scales_scalar',
torch.nn.Parameter(output2_scales, requires_grad=False))
layer.register_parameter(
'w2_input_scale_inv',
torch.nn.Parameter(1.0 / layer.w2_input_scale, requires_grad=False))
def build_flashinfer_fp8_cutlass_moe_prepare_finalize(
moe: Optional[FusedMoEConfig],
layer: torch.nn.Module,
) -> mk.FusedMoEPrepareAndFinalize:
"""Create a FlashInfer CUTLASS fused-MoE prepare finalize kernel"""
use_dp = moe.moe_parallel_config.dp_size > 1 if moe is not None else False
return FlashInferCutlassMoEPrepareAndFinalize(
use_dp, a1_gscale=layer.w13_input_scale)
def select_cutlass_fp8_gemm_impl(
moe: Optional[FusedMoEConfig],
layer: torch.nn.Module,
out_dtype: Optional[torch.dtype] = None,
) -> mk.FusedMoEPermuteExpertsUnpermute:
"""Return a GEMM *experts* implementation for fused-MoE layers"""
from vllm.model_executor.models.llama4 import Llama4MoE
assert layer.custom_routing_function == Llama4MoE.custom_routing_function, \
"FusedMoE flashinfer kernels are only supported for Llama4"
if moe is not None:
return FlashInferExperts(
g1_alphas=layer.output1_scales_gate_scalar,
g2_alphas=layer.output2_scales_scalar,
a1_gscale=layer.w13_input_scale,
a2_gscale=layer.w2_input_scale_inv,
out_dtype=moe.in_dtype,
quant_dtype=torch.float8_e4m3fn,
ep_rank=moe.moe_parallel_config.ep_rank,
ep_size=moe.moe_parallel_config.ep_size,
tp_rank=moe.moe_parallel_config.tp_rank,
tp_size=moe.moe_parallel_config.tp_size,
)
assert out_dtype is not None, (
"If moe config is None, out_dtype must be passed")
return FlashInferExperts(
g1_alphas=layer.output1_scales_gate_scalar,
g2_alphas=layer.output2_scales_scalar,
a1_gscale=layer.w13_input_scale,
a2_gscale=layer.w2_input_scale_inv,
out_dtype=out_dtype,
quant_dtype=torch.float8_e4m3fn,
)
def flashinfer_cutlass_moe_fp8(
hidden_states: torch.Tensor,
layer: torch.nn.Module,
topk_weights: torch.Tensor,
topk_ids: torch.Tensor,
inplace: bool = False,
activation: str = "silu",
global_num_experts: int = -1,
expert_map: Optional[torch.Tensor] = None,
apply_router_weight_on_input: bool = False,
) -> torch.Tensor:
fused_experts = mk.FusedMoEModularKernel(
build_flashinfer_fp8_cutlass_moe_prepare_finalize(moe=None,
layer=layer),
select_cutlass_fp8_gemm_impl(moe=None,
layer=layer,
out_dtype=hidden_states.dtype))
return fused_experts(
hidden_states,
layer.w13_weight,
layer.w2_weight,
topk_weights,
topk_ids,
inplace=inplace,
activation=activation,
global_num_experts=global_num_experts,
expert_map=expert_map,
apply_router_weight_on_input=apply_router_weight_on_input,
)
def get_flashinfer_moe_backend() -> FlashinferMoeBackend:
flashinfer_moe_backend = envs.VLLM_FLASHINFER_MOE_BACKEND
if flashinfer_moe_backend == "throughput":
return FlashinferMoeBackend.CUTLASS
elif flashinfer_moe_backend == "latency":
return FlashinferMoeBackend.TENSORRT_LLM
allowed_backends = ["throughput", "latency"]
raise ValueError(
f"Unknown flashinfer moe backend: {flashinfer_moe_backend}"
f" expected one of {allowed_backends}")