biondizzle/vllm
1
0
Fork 0
Code Issues Pull Requests Actions 2 Packages Projects Releases Wiki Activity

[Kernel] FlashInfer: switch allreduce fusion to unified API (#33985)

Browse Source 
Signed-off-by: Mohammad Miadh Angkad <176301910+mmangkad@users.noreply.github.com>
This commit is contained in:
Mohammad Miadh Angkad
2026-02-09 23:43:24 +08:00
committed by GitHub
parent cb62e86f83
commit d4f123cc48
3 changed files with 80 additions and 114 deletions
Download Patch File Download Diff File Expand all files Collapse all files

123
benchmarks/kernels/benchmark_fused_collective.py
View File

@@ -5,7 +5,7 @@
Benchmark for FlashInfer fused collective operations vs standard operations.
This benchmark compares:
1. FlashInfer's trtllm_allreduce_fusion (fused allreduce + rmsnorm + optional quant)
1. FlashInfer's allreduce_fusion (fused allreduce + rmsnorm + optional quant)
2. Standard tensor_model_parallel_all_reduce + separate rmsnorm/quant operations
Usage with torchrun:
@@ -24,7 +24,6 @@ import torch.distributed as dist # type: ignore
from vllm.config.vllm import CompilationConfig, VllmConfig, set_current_vllm_config
from vllm.distributed import (
get_tp_group,
tensor_model_parallel_all_reduce,
)
from vllm.distributed.parallel_state import (
@@ -52,11 +51,12 @@ logger = init_logger(__name__)
try:
import flashinfer.comm as flashinfer_comm # type: ignore
if not hasattr(flashinfer_comm, "trtllm_allreduce_fusion"):
if not (
hasattr(flashinfer_comm, "allreduce_fusion")
and hasattr(flashinfer_comm, "create_allreduce_fusion_workspace")
):
flashinfer_comm = None
logger.warning(
"FlashInfer comm module found but missing trtllm_allreduce_fusion"
)
logger.warning("FlashInfer comm module found but missing allreduce_fusion API")
except ImportError:
flashinfer_comm = None
logger.warning("FlashInfer not found, only benchmarking standard operations")
@@ -75,7 +75,7 @@ _FI_MAX_SIZES = {
}
# Global workspace tensor for FlashInfer
_FI_WORKSPACE_TENSOR = None
_FI_WORKSPACE = None
def setup_flashinfer_workspace(
@@ -83,10 +83,10 @@ def setup_flashinfer_workspace(
rank: int,
hidden_dim: int,
max_token_num: int,
use_fp32_lamport: bool = False,
dtype: torch.dtype,
):
"""Setup FlashInfer workspace for fused allreduce operations."""
global _FI_WORKSPACE_TENSOR
global _FI_WORKSPACE
if flashinfer_comm is None:
return None, None
@@ -96,33 +96,29 @@ def setup_flashinfer_workspace(
return None, None
try:
# Create IPC workspace
ipc_handles, workspace_tensor = (
flashinfer_comm.trtllm_create_ipc_workspace_for_all_reduce_fusion(
tp_rank=rank,
tp_size=world_size,
max_token_num=max_token_num,
hidden_dim=hidden_dim,
group=get_tp_group().device_group,
use_fp32_lamport=use_fp32_lamport,
)
workspace = flashinfer_comm.create_allreduce_fusion_workspace(
backend="trtllm",
world_size=world_size,
rank=rank,
max_token_num=max_token_num,
hidden_dim=hidden_dim,
dtype=dtype,
)
_FI_WORKSPACE_TENSOR = workspace_tensor
return ipc_handles, workspace_tensor
_FI_WORKSPACE = workspace
return workspace
except Exception as e:
logger.error("Failed to setup FlashInfer workspace: %s", e)
return None, None
return None
def cleanup_flashinfer_workspace(ipc_handles):
def cleanup_flashinfer_workspace(workspace):
"""Cleanup FlashInfer workspace."""
if flashinfer_comm is None or ipc_handles is None:
if flashinfer_comm is None or workspace is None:
return
try:
group = get_tp_group().device_group
flashinfer_comm.trtllm_destroy_ipc_workspace_for_all_reduce(ipc_handles, group)
workspace.destroy()
except Exception as e:
logger.error("Failed to cleanup FlashInfer workspace: %s", e)
@@ -132,25 +128,15 @@ class FlashInferFusedAllReduceParams:
def __init__(
self,
rank: int,
world_size: int,
use_fp32_lamport: bool = False,
max_token_num: int = 1024,
):
self.rank = rank
self.world_size = world_size
self.use_fp32_lamport = use_fp32_lamport
self.trigger_completion_at_end = True
self.launch_with_pdl = True
self.fp32_acc = True
self.max_token_num = max_token_num
def get_trtllm_fused_allreduce_kwargs(self):
return {
"world_rank": self.rank,
"world_size": self.world_size,
"launch_with_pdl": self.launch_with_pdl,
"trigger_completion_at_end": self.trigger_completion_at_end,
"fp32_acc": self.fp32_acc,
}
@@ -165,7 +151,7 @@ def flashinfer_fused_allreduce_rmsnorm(
norm_out: torch.Tensor | None = None,
):
"""FlashInfer fused allreduce + rmsnorm operation."""
if flashinfer_comm is None or _FI_WORKSPACE_TENSOR is None:
if flashinfer_comm is None or _FI_WORKSPACE is None:
raise RuntimeError("FlashInfer not available or workspace not initialized")
if norm_out is None:
@@ -174,18 +160,15 @@ def flashinfer_fused_allreduce_rmsnorm(
else:
residual_out = input_tensor
flashinfer_comm.trtllm_allreduce_fusion(
allreduce_in=input_tensor,
token_num=input_tensor.shape[0],
flashinfer_comm.allreduce_fusion(
input=input_tensor,
workspace=_FI_WORKSPACE,
pattern=flashinfer_comm.AllReduceFusionPattern.kARResidualRMSNorm,
residual_in=residual,
residual_out=residual_out,
norm_out=norm_out,
rms_gamma=rms_gamma,
rms_eps=rms_eps,
hidden_dim=input_tensor.shape[-1],
workspace_ptrs=_FI_WORKSPACE_TENSOR,
pattern_code=flashinfer_comm.AllReduceFusionPattern.kARResidualRMSNorm,
allreduce_out=None,
quant_out=None,
scale_out=None,
layout_code=flashinfer_comm.QuantizationSFLayout.SWIZZLED_128x4,
@@ -207,7 +190,7 @@ def flashinfer_fused_allreduce_rmsnorm_fp8_quant(
quant_out: torch.Tensor | None = None,
):
"""FlashInfer fused allreduce + rmsnorm + FP8 quantization."""
if flashinfer_comm is None or _FI_WORKSPACE_TENSOR is None:
if flashinfer_comm is None or _FI_WORKSPACE is None:
raise RuntimeError("FlashInfer not available or workspace not initialized")
if norm_out is None:
@@ -216,18 +199,15 @@ def flashinfer_fused_allreduce_rmsnorm_fp8_quant(
else:
residual_out = input_tensor
flashinfer_comm.trtllm_allreduce_fusion(
allreduce_in=input_tensor,
token_num=input_tensor.shape[0],
flashinfer_comm.allreduce_fusion(
input=input_tensor,
workspace=_FI_WORKSPACE,
pattern=flashinfer_comm.AllReduceFusionPattern.kARResidualRMSNormFP8Quant,
residual_in=residual,
residual_out=residual_out,
norm_out=norm_out,
rms_gamma=rms_gamma,
rms_eps=rms_eps,
hidden_dim=input_tensor.shape[-1],
workspace_ptrs=_FI_WORKSPACE_TENSOR,
pattern_code=flashinfer_comm.AllReduceFusionPattern.kARResidualRMSNormFP8Quant,
allreduce_out=None,
quant_out=quant_out,
scale_out=None,
layout_code=flashinfer_comm.QuantizationSFLayout.SWIZZLED_128x4,
@@ -250,7 +230,7 @@ def flashinfer_fused_allreduce_rmsnorm_fp4_quant(
norm_out: torch.Tensor | None = None,
):
"""FlashInfer fused allreduce + rmsnorm + FP4 quantization."""
if flashinfer_comm is None or _FI_WORKSPACE_TENSOR is None:
if flashinfer_comm is None or _FI_WORKSPACE is None:
raise RuntimeError("FlashInfer not available or workspace not initialized")
if norm_out is None:
@@ -259,18 +239,15 @@ def flashinfer_fused_allreduce_rmsnorm_fp4_quant(
else:
residual_out = input_tensor
flashinfer_comm.trtllm_allreduce_fusion(
allreduce_in=input_tensor,
token_num=input_tensor.shape[0],
flashinfer_comm.allreduce_fusion(
input=input_tensor,
workspace=_FI_WORKSPACE,
pattern=flashinfer_comm.AllReduceFusionPattern.kARResidualRMSNormFP4Quant,
residual_in=residual,
residual_out=residual_out,
norm_out=norm_out,
rms_gamma=rms_gamma,
rms_eps=rms_eps,
hidden_dim=input_tensor.shape[-1],
workspace_ptrs=_FI_WORKSPACE_TENSOR,
pattern_code=flashinfer_comm.AllReduceFusionPattern.kARResidualRMSNormFP4Quant,
allreduce_out=None,
quant_out=quant_out,
scale_out=output_scale,
layout_code=flashinfer_comm.QuantizationSFLayout.SWIZZLED_128x4,
@@ -1040,23 +1017,31 @@ def main():
configs = list(itertools.product(args.num_tokens, dtypes, residual_options))
# Setup FlashInfer workspace if available
ipc_handles = None
workspace = None
allreduce_params = None
if flashinfer_comm is not None:
# Use the largest hidden dimension for workspace setup
max_element_size = max(torch.finfo(dt).bits // 8 for dt in dtypes)
workspace_dtype = (
torch.float32
if max_element_size == 4
else (torch.bfloat16 if torch.bfloat16 in dtypes else torch.float16)
)
max_num_token = _FI_MAX_SIZES.get(world_size) // (
args.hidden_dim * world_size * 2
args.hidden_dim * max_element_size
)
ipc_handles, workspace_tensor = setup_flashinfer_workspace(
world_size, rank, args.hidden_dim, max_num_token
workspace = setup_flashinfer_workspace(
world_size,
rank,
args.hidden_dim,
max_num_token,
dtype=workspace_dtype,
)
if workspace_tensor is not None:
if workspace is not None:
allreduce_params = FlashInferFusedAllReduceParams(
rank=rank,
world_size=world_size,
max_token_num=max_num_token,
)
@@ -1119,8 +1104,8 @@ def main():
finally:
# Cleanup
if ipc_handles is not None:
cleanup_flashinfer_workspace(ipc_handles)
if workspace is not None:
cleanup_flashinfer_workspace(workspace)
dist.barrier()

5
tests/compile/passes/distributed/test_fusion_all_reduce.py
View File

@@ -202,9 +202,10 @@ class TestAllReduceFusedAddRMSNormStaticQuantFP4Model(torch.nn.Module):
@pytest.mark.skipif(envs.VLLM_TARGET_DEVICE not in ["cuda"], reason="Only test on CUDA")
@pytest.mark.skipif(
not find_spec("flashinfer")
or not has_module_attribute("flashinfer.comm", "trtllm_allreduce_fusion"),
or not has_module_attribute("flashinfer.comm", "allreduce_fusion")
or not has_module_attribute("flashinfer.comm", "create_allreduce_fusion_workspace"),
reason="flashinfer is not found or flashinfer "
"is not compiled with trtllm_allreduce_fusion",
"is not compiled with allreduce_fusion",
)
def test_all_reduce_fusion_pass_replace(
test_model: torch.nn.Module,

66
vllm/compilation/passes/fusion/allreduce_rms_fusion.py
View File

@@ -1,5 +1,6 @@
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import contextlib
from importlib.util import find_spec
from types import ModuleType
@@ -36,7 +37,9 @@ if find_spec("flashinfer"):
try:
import flashinfer.comm as _flashinfer_comm
if hasattr(_flashinfer_comm, "trtllm_allreduce_fusion"):
if hasattr(_flashinfer_comm, "allreduce_fusion") and hasattr(
_flashinfer_comm, "create_allreduce_fusion_workspace"
):
flashinfer_comm = _flashinfer_comm
except ImportError:
pass
@@ -79,7 +82,7 @@ _FI_ALLREDUCE_ONE_SHOT_MAX_SIZES_MB: dict[int, dict[int, float]] = {
if flashinfer_comm is not None:
_FI_WORKSPACE_TENSOR = None
_FI_WORKSPACE = None
MiB = 1024 * 1024
def call_trtllm_fused_allreduce_norm(
@@ -87,10 +90,8 @@ if flashinfer_comm is not None:
residual: torch.Tensor,
rms_gamma: torch.Tensor,
rms_eps: float,
world_rank: int,
world_size: int,
launch_with_pdl: bool,
trigger_completion_at_end: bool,
fp32_acc: bool,
max_token_num: int,
pattern_code: int,
@@ -121,7 +122,7 @@ if flashinfer_comm is not None:
max_one_shot_size is None or current_tensor_size <= max_one_shot_size * MiB
)
assert _FI_WORKSPACE_TENSOR is not None, (
assert _FI_WORKSPACE is not None, (
"Flashinfer must be enabled when using flashinfer"
)
if norm_out is None:
@@ -134,24 +135,18 @@ if flashinfer_comm is not None:
residual_out = allreduce_in
# For the sizes that are smaller than the max size,
# we only use flashinfer one shot allreduce
flashinfer_comm.trtllm_allreduce_fusion(
allreduce_in=allreduce_in,
token_num=allreduce_in.shape[0],
flashinfer_comm.allreduce_fusion(
input=allreduce_in,
workspace=_FI_WORKSPACE,
pattern=pattern_code,
residual_in=residual,
residual_out=residual_out,
norm_out=norm_out,
rms_gamma=rms_gamma,
rms_eps=rms_eps,
world_rank=world_rank,
world_size=world_size,
hidden_dim=allreduce_in.shape[-1],
workspace_ptrs=_FI_WORKSPACE_TENSOR,
launch_with_pdl=launch_with_pdl,
use_oneshot=use_oneshot,
trigger_completion_at_end=trigger_completion_at_end,
fp32_acc=fp32_acc,
pattern_code=pattern_code,
allreduce_out=None,
quant_out=quant_out,
scale_out=scale_out,
# in vllm we only support swizzled layout
@@ -164,10 +159,8 @@ if flashinfer_comm is not None:
residual: torch.Tensor,
rms_gamma: torch.Tensor,
rms_eps: float,
world_rank: int,
world_size: int,
launch_with_pdl: bool,
trigger_completion_at_end: bool,
fp32_acc: bool,
max_token_num: int,
pattern_code: int,
@@ -200,25 +193,18 @@ class FlashInferFusedAllReduceParams:
def __init__(
self,
rank: int,
world_size: int,
use_fp32_lamport: bool = False,
max_token_num: int = 1024,
) -> None:
self.rank = rank
self.world_size = world_size
self.use_fp32_lamport = use_fp32_lamport
self.trigger_completion_at_end = True
self.launch_with_pdl = True
self.fp32_acc = True
self.max_token_num = max_token_num
def get_trtllm_fused_allreduce_kwargs(self) -> dict[str, bool | int]:
return {
"world_rank": self.rank,
"world_size": self.world_size,
"launch_with_pdl": self.launch_with_pdl,
"trigger_completion_at_end": self.trigger_completion_at_end,
"fp32_acc": self.fp32_acc,
"max_token_num": self.max_token_num,
}
@@ -712,7 +698,6 @@ class AllReduceFusionPass(VllmPatternMatcherPass):
self.hidden_dim = config.model_config.get_hidden_size()
self.group = get_tp_group().device_group
rank = get_tensor_model_parallel_rank()
use_fp32_lamport = self.model_dtype == torch.float32
if flashinfer_comm is None:
logger.warning(
"Flashinfer is not installed or comm module not found, "
@@ -730,7 +715,7 @@ class AllReduceFusionPass(VllmPatternMatcherPass):
self.tp_size,
)
return
element_size = 4 if use_fp32_lamport else 2
element_size = torch.tensor([], dtype=self.model_dtype).element_size()
self.max_token_num = max_size // (self.hidden_dim * element_size)
# take the min to save workspace size and we'll never use more
# than max_num_batched_tokens anyways
@@ -744,23 +729,19 @@ class AllReduceFusionPass(VllmPatternMatcherPass):
scope="global",
)
self.ipc_handles, workspace_tensor = (
flashinfer_comm.trtllm_create_ipc_workspace_for_all_reduce_fusion(
tp_rank=rank,
tp_size=self.tp_size,
max_token_num=self.max_token_num,
hidden_dim=self.hidden_dim,
group=self.group,
use_fp32_lamport=use_fp32_lamport,
)
self.workspace = flashinfer_comm.create_allreduce_fusion_workspace(
backend="trtllm",
world_size=self.tp_size,
rank=rank,
max_token_num=self.max_token_num,
hidden_dim=self.hidden_dim,
dtype=self.model_dtype,
)
global _FI_WORKSPACE_TENSOR
_FI_WORKSPACE_TENSOR = workspace_tensor
global _FI_WORKSPACE
_FI_WORKSPACE = self.workspace
self.allreduce_params = FlashInferFusedAllReduceParams(
rank=rank,
world_size=self.tp_size,
use_fp32_lamport=use_fp32_lamport,
max_token_num=self.max_token_num,
)
@@ -832,7 +813,6 @@ class AllReduceFusionPass(VllmPatternMatcherPass):
def __del__(self) -> None:
if getattr(self, "disabled", True):
return
if flashinfer_comm is not None:
flashinfer_comm.trtllm_destroy_ipc_workspace_for_all_reduce(
self.ipc_handles, self.group
)
if getattr(self, "workspace", None) is not None:
with contextlib.suppress(Exception):
self.workspace.destroy()