Files
xc-llm-ascend/vllm_ascend/patch/worker/patch_common/patch_metrics.py
Mengqing Cao 6ee7f5cf71 [SpecDecode] Add spec decode support (#500)
### What this PR does / why we need it?
Backport: https://github.com/vllm-project/vllm-ascend/pull/252
This support speculative decoding in Ascend, including speculating with
a draft model、by matching n-grams in the prompt、using MLP speculators
and using EAGLE based draft models.

Backport: https://github.com/vllm-project/vllm-ascend/pull/423
spec decode MultiStepWorker support TP1DraftModelRunner fully, support
run the draft_model_runner with multi-step prepare on the NPU directly
and support draft_model_runner use MLA.

1. before this pr, `MultiStepWorker` would not step into the branch
using NPU prepare, but only into the branch using CPU prepare (`line 52`
of `vllm_ascend/patch/patch_multi_step_worker.py`). Although this has
`no effect` on the `correct operation` of speculative decoding and the
performance of the two branches is basically the same as of the current
version, I support entering this branch in this PR. In general, there
are two main changes in `patch_multi_step_worker.py`: first, the
`is_cuda_like()` check is removed and the `TP1DraftModelRunner`
rewritten in vllm_ascend is used; second, the
`supports_gpu_multi_step()` function is made to return true on NPU
devices when outer Multi_step_worker could work correct.

3. before this pr, `TP1DraftModelRunner` only supports Attention on NPU,
but not MLA. The relevant adaptation is in
`vllm_ascend/worker/draft_model_runner.py`. Although I don’t know why
the `input_positions` of `model_input.attn_metadata` in vllm-ascend
needs to be added in `execute_model`, it is done in `model_runner.py`,
so I also made corresponding changes. Otherwise, when atten_backend is
MLA, it will prompt that input_positions cannot be found.

4. I commented out two lines in `draft_model_runner.py` in `line118` to
support the scenario of K>1.
  ```
  # lora_mapping=model_input.lora_mapping,
  # lora_requests=model_input.lora_requests,
  ```
I added comments. In the future, when vllm-ascend supports lora feature,
the changes here can be restored.

TODO:
- [ ] revert the patch when the related issues are addressed in vllm

### How was this patch tested?
CI passed with new added test.
- e2e test for medusa proposer:
tests/singlecard/spec_decode/e2e/test_medusa_correctness.py
- e2e test for mlp proposer:
tests/singlecard/spec_decode/e2e/test_mlp_correctness.py
- e2e test for n-gram proposer:
tests/singlecard/spec_decode/e2e/test_ngram_correctness.py

Tests for patched files:
- tests/singlecard/spec_decode/test_dynamic_spec_decode.py
- tests/singlecard/spec_decode/test_multi_step_worker.py
- tests/singlecard/spec_decode/test_ngram_worker.py
- tests/singlecard/spec_decode/test_spec_decode_worker.py

---------

Signed-off-by: MengqingCao <cmq0113@163.com>
Co-authored-by: mengwei805 <mengwei25@huawei.com>
2025-04-17 20:16:32 +08:00

89 lines
3.2 KiB
Python

#
# Copyright (c) 2025 Huawei Technologies Co., Ltd. All Rights Reserved.
# This file is a part of the vllm-ascend project.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
from typing import Callable, Optional, Union
import torch
import torch_npu
from vllm.spec_decode.metrics import (AsyncMetricsCollector,
SpecDecodeWorkerMetrics)
Timer = Callable[[], float]
# TODO: revert this patch when the cuda hard code is removed in vllm
# init_tensors: Modified the hard-coded cuda judgment logic to npu;
# maybe_collect_rejsample_metrics: Removed the check for current_platform.is_cuda_alike()
def init_tensors(self,
rank: int,
device_type: Union[torch.device, str] = 'npu') -> None:
self._rank = rank
if isinstance(device_type, torch.device):
device_type = device_type.type
if device_type == 'npu':
self._copy_stream = torch_npu.npu.Stream()
def maybe_collect_rejsample_metrics(
self, k: int) -> Optional[SpecDecodeWorkerMetrics]:
# If a copy was initiated in the previous call, collect and return.
if self._in_flight_copy is not None:
ready_event = self._in_flight_copy
self._in_flight_copy = None
return self._collect_rejsample_metrics(k, ready_event)
# Otherwise, check if we should start a new copy.
if self._should_collect_rejsample_metrics(self._timer()):
assert self._in_flight_copy is None
self._in_flight_copy = self._copy_rejsample_metrics_async()
return None
def _copy_rejsample_metrics_async(self) -> torch.npu.Event:
"""
TODO: torch.cuda.xxx --> torch.npu.xxx
Copy rejection/typical-acceptance sampling metrics
(number of accepted tokens, etc) to CPU asynchronously.
Returns a NPU event recording when the copy is complete.
"""
assert self._copy_stream is not None
self._copy_stream.wait_stream(torch.npu.current_stream())
with torch.npu.stream(self._copy_stream):
self._aggregate_num_accepted_tokens.copy_(
self.spec_decode_sampler.num_accepted_tokens, non_blocking=True)
self._aggregate_num_emitted_tokens.copy_(
self.spec_decode_sampler.num_emitted_tokens, non_blocking=True)
# Number of draft tokens is calculated on CPU, so no copy is
# required.
self._aggregate_num_draft_tokens = (
self.spec_decode_sampler.num_draft_tokens)
aggregate_metrics_ready = torch.npu.Event()
aggregate_metrics_ready.record(self._copy_stream)
return aggregate_metrics_ready
AsyncMetricsCollector.init_tensors = init_tensors
AsyncMetricsCollector.maybe_collect_rejsample_metrics = maybe_collect_rejsample_metrics
AsyncMetricsCollector._copy_rejsample_metrics_async = _copy_rejsample_metrics_async