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[perf] replace all_reduce for kv_consumer and support different num_tokens among all ranks (#4983)

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pick from https://github.com/vllm-project/vllm-ascend/pull/4736 to fix
the merge conflict

### What this PR does / why we need it?
Currently, the all_reduce operation in _sync_metadata_across_dp is
performed with gloo backend which is extremely time-consuming when
DPEngineCores are in different nodes. This operation cannot be ignored
by async scheduling in multi-node-scenarios with speculative decoding
(e.g., EAGLE, mtp).

This pr eliminates the all_reduce operation for D Nodes and change the
input parameter of MoEDispatch & MoeCombine operators to make MC2EP
support different num_tokens across all ranks.

### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Tested with PD disaggregation (2P: DP2TP8EP16 1D: DP8TP4EP32) scenarios
while enabling async scheduling. This pr can remove cross-node
all_reduce with gloo backend and further reduce latency with correct
accuracy.

---------

Signed-off-by: linfeng-yuan <1102311262@qq.com>
Co-authored-by: linfeng-yuan <1102311262@qq.com>
This commit is contained in:
wangxiyuan
2025-12-13 18:59:54 +08:00
committed by GitHub
parent 5211e991ad
commit fd7c929145
7 changed files with 69 additions and 26 deletions
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6
vllm_ascend/ops/fused_moe/fused_moe.py
View File

@@ -116,7 +116,11 @@ class AscendUnquantizedFusedMoEMethod(UnquantizedFusedMoEMethod):
# to avoid accumulating too much tokens on a single rank.
# currently it is only activated when doing profile runs.
if enable_force_load_balance:
topk_ids = torch.randint_like(topk_ids, 0, global_num_experts)
random_matrix = torch.rand(topk_ids.size(0),
global_num_experts,
device=topk_ids.device)
topk_ids = torch.argsort(
random_matrix, dim=1)[:, :topk_ids.size(1)].to(topk_ids.dtype)
moe_comm_method = get_forward_context().moe_comm_method
return moe_comm_method.fused_experts(

36
vllm_ascend/ops/fused_moe/token_dispatcher.py
View File

@@ -25,6 +25,7 @@ from typing import Any, Optional
import torch
import torch_npu
from vllm.config import get_current_vllm_config
from vllm.distributed.parallel_state import get_ep_group
from vllm_ascend.distributed.parallel_state import get_mc2_group
@@ -100,15 +101,31 @@ class TokenDispatcherWithMC2(MoETokenDispatcher):
self.need_extra_args = (
get_ascend_device_type() == AscendDeviceType._910_93)
# NOTE: Currently, when in A3, we need to pass in some extra param into dispatch & combine
self.a3_need_extra_args = \
get_ascend_device_type() == AscendDeviceType._910_93
# NOTE: When in A2, setting the environment variables HCCL_INTRA_PCIE_ENABLE=1 and
# HCCL_INTRA_ROCE_ENABLE=0 can reduce cross-machine communication traffic and significantly
# improve communication performance.
self.need_expert_scale = is_hierarchical_communication_enabled()
self.with_quant = False
# Here we need to calculate the global_bs = max_bs_per_rank * ep_world_size to execute
# dispatch & combine operators with different input num_tokens per rank.
vllm_config = get_current_vllm_config()
scheduler_config = vllm_config.scheduler_config
compilation_config = vllm_config.compilation_config
speculative_config = vllm_config.speculative_config
tp_size = vllm_config.parallel_config.tensor_parallel_size
uniform_decode_query_len = 1 if not speculative_config else \
1 + speculative_config.num_speculative_tokens
decode_max_num_seqs = getattr(scheduler_config, 'decode_max_num_seqs',
0)
max_num_reqs = max(scheduler_config.max_num_seqs, decode_max_num_seqs)
if compilation_config.cudagraph_capture_sizes:
max_num_tokens = compilation_config.max_cudagraph_capture_size
else:
max_num_tokens = min(max_num_reqs * uniform_decode_query_len, 512)
num_tokens_per_tp_rank = (max_num_tokens + tp_size - 1) // tp_size
self.global_bs = num_tokens_per_tp_rank * self.ep_world_size
def get_dispatch_mc2_kwargs(
self,
hidden_states: torch.Tensor,
@@ -130,7 +147,7 @@ class TokenDispatcherWithMC2(MoETokenDispatcher):
"expert_shard_type": 0,
"shared_expert_rank_num": 0,
"moe_expert_num": moe_expert_num,
"global_bs": 0,
"global_bs": self.global_bs,
"expert_token_nums_type": 0,
}
@@ -147,10 +164,6 @@ class TokenDispatcherWithMC2(MoETokenDispatcher):
"tp_world_size": 1,
"tp_rank_id": 0,
})
if self.a3_need_extra_args and self.enable_dispatch_v2:
stage1_kwargs.update({
"x_active_mask": mc2_mask,
})
if self.need_expert_scale:
stage1_kwargs.update({
"expert_scales":
@@ -214,7 +227,6 @@ class TokenDispatcherWithMC2(MoETokenDispatcher):
context_metadata = {
"topk_ids": topk_ids,
"topk_weights": topk_weights,
"mc2_mask": mc2_mask,
"expert_map": expert_map,
"ep_recv_counts": ep_recv_counts,
"tp_recv_counts": tp_recv_counts,
@@ -243,7 +255,6 @@ class TokenDispatcherWithMC2(MoETokenDispatcher):
ep_recv_counts = context_metadata["ep_recv_counts"]
tp_recv_counts = context_metadata["tp_recv_counts"]
assist_info_for_combine = context_metadata["assist_info_for_combine"]
mc2_mask = context_metadata["mc2_mask"]
expand_scales = context_metadata["expand_scales"]
assert expert_map is not None
@@ -256,7 +267,7 @@ class TokenDispatcherWithMC2(MoETokenDispatcher):
"expert_shard_type": 0,
"shared_expert_rank_num": 0,
"moe_expert_num": moe_expert_num,
"global_bs": 0,
"global_bs": self.global_bs,
}
if self.with_quant:
@@ -285,9 +296,6 @@ class TokenDispatcherWithMC2(MoETokenDispatcher):
"tp_rank_id": 0,
})
if self.a3_need_extra_args and self.enable_dispatch_v2:
stage3_kwargs["x_active_mask"] = mc2_mask
kwargs_mc2.update(stage3_kwargs)
return kwargs_mc2