Files
xc-llm-ascend/vllm_ascend/worker/multi_step_runner.py
Tony 4c9d78a035 support multistep decode (#299)
Add multi step scheduler support for vllm-ascend

Signed-off-by: new-TonyWang <wangtonyyu222@gmail.com>
2025-03-11 19:20:06 +08:00

675 lines
28 KiB
Python

import dataclasses
import functools
from dataclasses import dataclass
from typing import Any, Callable, Dict, List, Optional, Tuple, Union
import torch
from torch import nn
from vllm.distributed import get_pp_group
from vllm.logger import init_logger
from vllm.model_executor.layers.sampler import (PromptLogprobs, SampleLogprobs,
SamplerOutput,
SamplingMetadata, get_logprobs,
get_pythonized_sample_results)
from vllm.model_executor.model_loader.tensorizer import TensorizerConfig
from vllm.sequence import (CompletionSequenceGroupOutput, IntermediateTensors,
Logprob, SequenceGroupMetadata, SequenceOutput)
from vllm.worker.multi_step_model_runner import (ModelOutput,
PythonizationCache,
StatefulModelInput)
from vllm_ascend.utils import current_stream
from vllm_ascend.worker.model_runner import (
ModelInputForNPUWithSamplingMetadata, NPUModelRunnerBase)
logger = init_logger(__name__)
@dataclass(frozen=False)
class NPUStatefulModelInput(StatefulModelInput):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
def record_step_event(self, current_stream: torch.npu.Stream):
# record the event for the current step so that the next step can sync
# on it. We modulo by 2 to keep the events in a circular buffer and
# support any attn backends that may be supported in the future. ie
# Flashinfer would want two DecodeWrappers to overlap the CPU and NPU.
self.step_cuda_events[self.current_step & 1] = \
torch.npu.Event(blocking=True)
self.step_cuda_events[self.current_step & 1].record(current_stream)
@dataclass(frozen=False)
class NPUModelOutput(ModelOutput):
logprobs: Optional["torch.Tensor"] = None
def _pythonize_sampler_output(self, input_metadata: "StatefulModelInput",
copy_stream: torch.npu.Stream,
pinned_sampled_token_buffer: torch.Tensor,
blocking: bool) -> bool:
"""
If blocking is set, will block until the forward pass for the output is
ready and pythonize the output. Upon completing Pythonization, erases
self.logprobs (note that a non-blocking call that is performed when
the sampler output is not yet ready, will not erase self.logprobs.)
"""
assert self.sampled_token_ids is not None
if not blocking and not self.sampler_output_ready_event.query():
return False
if blocking:
self.sampler_output_ready_event.synchronize()
with torch.npu.stream(copy_stream):
_pythonize_sampler_output(input_metadata, self.sampler_output,
pinned_sampled_token_buffer,
self.sampled_token_ids, self.logprobs,
self.pythonization_cache)
# Erase the logprobs GPU-side tensor.
# Note that although _pythonize_sampler_output() runs in its
# own CUDA stream, nonetheless _pythonize_sampler_output()
# cannot return until Pythonization is complete; therefore
# we know that by the time the CPU reaches this point,
# `self.logprobs` is no longer needed.
self.logprobs = None
return True
class MultiStepModelNPURunner(NPUModelRunnerBase[NPUStatefulModelInput]):
# mypy: enable-error-code=type-var
def __init__(self, base_model_runner: NPUModelRunnerBase, *args, **kwargs):
super().__init__(*args, **kwargs)
# uses the base model runner to execute the model and wraps it with
# multi-step logic
self._base_model_runner: NPUModelRunnerBase = base_model_runner
self.is_multi_step = self.scheduler_config.is_multi_step
self.pinned_sampled_token_ids: Optional[torch.Tensor] = None
# Using the PythonizationCache in Pipeline-Parallel clobbers the
# SequenceOutput and CompletionSequenceGroupOutput object.
# When cache-reset happens at the last step of a multi-step
# execution, there may be other on-going single-step/multi-step
# executions. The current caching implementation does not check
# for this.
self.pythonization_cache = PythonizationCache() \
if self.parallel_config.pipeline_parallel_size == 1 else None
def get_model(self) -> nn.Module:
return self.model
@functools.cached_property
def _copy_stream(self):
# used to copy tensors from NPU to CPU asynchronously
return torch.npu.Stream()
def make_model_input_from_broadcasted_tensor_dict(
self, tensor_dict: Dict[str, Any]) -> StatefulModelInput:
model_input = (NPUStatefulModelInput.from_broadcasted_tensor_dict(
tensor_dict,
attn_backend=self.attn_backend,
))
return model_input
def prepare_model_input(
self,
seq_group_metadata_list: List[SequenceGroupMetadata],
virtual_engine: int = 0,
finished_requests_ids: Optional[List[str]] = None
) -> StatefulModelInput:
frozen_model_input: ModelInputForNPUWithSamplingMetadata = \
self._base_model_runner.prepare_model_input(
seq_group_metadata_list,
virtual_engine,
finished_requests_ids)
assert frozen_model_input.query_lens is not None
assert frozen_model_input.seq_lens is not None
assert frozen_model_input.attn_metadata is not None
num_queries = len(frozen_model_input.query_lens)
num_seqs = len(frozen_model_input.seq_lens)
num_single_step_prefills = frozen_model_input.attn_metadata.num_prefills
model_input = NPUStatefulModelInput(
frozen_model_input=frozen_model_input,
num_seqs=num_seqs,
num_queries=num_queries,
num_single_step_prefills=num_single_step_prefills,
step_cuda_events=[torch.npu.Event(blocking=True)] * 2,
)
return model_input
def _async_process_outputs(self, model_input: StatefulModelInput,
output_proc_callback: Callable):
# Proceed with pythonization and output_proc in order.
# Stop on the first one that fails to pythonize
output_proc_callback()
cont = True
for step_num, model_output in enumerate(model_input.cached_outputs):
if not model_output.pythonized:
model_output.maybe_pythonize(model_input, self._copy_stream,
self.pinned_sampled_token_ids)
if model_output.pythonized:
ctx = output_proc_callback.keywords["ctx"] # type: ignore
ctx.append_output(
outputs=[model_output.sampler_output],
seq_group_metadata_list=ctx.seq_group_metadata_list,
scheduler_outputs=ctx.scheduler_outputs,
is_async=False,
is_last_step=False,
is_first_step_output=step_num == 0)
output_proc_callback()
else:
cont = False
if not cont:
break
def _final_process_outputs(
self, model_input: StatefulModelInput,
output_proc_callback: Optional[Callable]) -> List[SamplerOutput]:
assert model_input.frozen_model_input is not None
has_async_callback = output_proc_callback is not None
outputs = []
for step_num, output in enumerate(model_input.cached_outputs):
is_last_step = step_num == len(model_input.cached_outputs) - 1
# For non-async case:
# -- We simply add the outputs
# For async case:
# -- Invoke callback, pythonize, add to callback queue and repeat
# -- For last output, just add to callback queue
if has_async_callback:
assert output_proc_callback is not None
# Invoke callback before pythonize (to overlap with NPU)
output_proc_callback()
# Pythonize
if not output.pythonized:
output.pythonize(model_input, self._copy_stream,
self.pinned_sampled_token_ids)
# For non last step, add to callback queue to chain
# callbacks=>pythonize pairs (for NPU overlap)
if not is_last_step:
ctx = output_proc_callback.keywords[ # type: ignore
"ctx"] # type: ignore
ctx.append_output(
outputs=[output.sampler_output],
seq_group_metadata_list=ctx.
seq_group_metadata_list,
scheduler_outputs=ctx.scheduler_outputs,
is_async=False,
is_last_step=False,
is_first_step_output=step_num == 0)
else:
outputs.append(output.sampler_output)
else:
output.pythonize(model_input, self._copy_stream,
self.pinned_sampled_token_ids)
outputs.append(output.sampler_output)
return outputs
@torch.inference_mode()
def execute_model(
self,
model_input: StatefulModelInput,
kv_caches: List[torch.Tensor],
intermediate_tensors: Optional[IntermediateTensors] = None,
num_steps: int = 1,
) -> Optional[Union[List[SamplerOutput], IntermediateTensors]]:
"""
Execute the model for a single step and update multi-step
metadata
"""
assert num_steps == 1, "MultiStepModelRunner only supports num_steps=1"
frozen_model_input = model_input.frozen_model_input
assert frozen_model_input is not None
# path for warm up runs
if not model_input.is_multi_step:
return self._base_model_runner.execute_model(
frozen_model_input, kv_caches, intermediate_tensors, num_steps)
# make sure we skip the sampler on the lask rank and only pythonize
# if CPU is ahead.
if self.is_driver_worker and get_pp_group().is_last_rank:
if self.pinned_sampled_token_ids is None:
self.pinned_sampled_token_ids = torch.zeros(
(self.scheduler_config.max_num_seqs, 1),
dtype=torch.long,
device="cpu",
pin_memory=True)
self._base_model_runner.model.sampler.include_gpu_probs_tensor = (
True)
if frozen_model_input.sampling_metadata:
frozen_model_input.sampling_metadata.skip_sampler_cpu_output = (
True)
# some pre-execute model logic for multi-step:
# - if it's the first step, we need to reset the sampling tensors
# - if it's not the first step, we need to advance the step using the
# appended sampler output from last iteration
# - also maybe pythonize if CPU is ahead of NPU
stream = current_stream()
if not model_input.is_first_multi_step:
# Explicitly block on the previous step's forward to make sure we
# don't clobber any NPU tensors still in use.
# This is not needed for flashattn backend, but for other attn
# backends such as flashinfer that performs extra CPU operations on
# input metadata we may need to synchronize any CPU operations that
# might clobber enqueued forwards. (prevents CPU from running too
# far ahead if needed)
model_input.wait_previous_step()
model_input = self._advance_step(
model_input, model_input.cached_outputs[-1].sampler_output)
# frozen_model_input may have been updated
frozen_model_input = model_input.frozen_model_input
assert frozen_model_input is not None
if model_input.base_output_proc_callback is None:
assert frozen_model_input is not None
model_input.base_output_proc_callback = \
frozen_model_input.async_callback
if frozen_model_input.async_callback is not None:
assert model_input.base_output_proc_callback is not None
async_callback = functools.partial(
self._async_process_outputs,
model_input=model_input,
output_proc_callback=model_input.base_output_proc_callback)
model_input.frozen_model_input = dataclasses.replace( # type: ignore
model_input.frozen_model_input,
async_callback=async_callback)
# Update the local instance
frozen_model_input = model_input.frozen_model_input
assert frozen_model_input is not None
# Execute the model
output = self._base_model_runner.execute_model(frozen_model_input,
kv_caches,
intermediate_tensors,
num_steps=1)
# record the event for the current step so that the next step can sync
model_input.record_step_event(stream)
if get_pp_group().is_last_rank and self.is_driver_worker:
assert isinstance(output, list)
assert len(
output
) == 1, "MultiStepModelRunner requires single-step base_models"
# event for the pythonization so that we only pythonize if the
# tensors are ready. May be able to be combined with the step event
output_ready_event = torch.npu.Event()
output_ready_event.record(stream)
if self.parallel_config.pipeline_parallel_size > 1:
output[0].sampled_token_ids_cpu = output[
0].sampled_token_ids.cpu()
model_input.cached_outputs.append(
NPUModelOutput(output[0], output_ready_event,
output[0].sampled_token_ids, False,
output[0].logprobs, self.pythonization_cache))
# These NPU tensors are not required by multi-step;
# erase them to ensure they are not pythonized or
# transferred to CPU
output[0].sampled_token_ids = None
output[0].sampled_token_probs = None
output[0].logprobs = None
# Pythonize the output if CPU is ahead and the previous step is
# ready.
if frozen_model_input.async_callback is None:
for model_output in model_input.cached_outputs:
model_output.maybe_pythonize(model_input,
self._copy_stream,
self.pinned_sampled_token_ids)
model_input.current_step += 1
if not get_pp_group().is_last_rank:
# Should be IntermediateTensors
assert isinstance(output, IntermediateTensors)
return output
if not self.is_driver_worker:
return []
# Pythonize the output and block if needed since it is the last step
if model_input.is_last_step:
outputs = self._final_process_outputs(
model_input, model_input.base_output_proc_callback)
if self.pythonization_cache:
self.pythonization_cache.reset()
return outputs
# should be [SamplerOutput]
return output
def _update_sampling_metadata(self, sampling_metadata: SamplingMetadata,
num_seqs: Optional[int], num_queries: int):
assert sampling_metadata.num_prompts == 0
assert len(sampling_metadata.seq_groups) == num_queries
assert sampling_metadata.selected_token_indices.shape == (
num_queries, )
# assert sampling_metadata.categorized_sample_indices == TODO: Add if needed # noqa: E501
# Verify that all sequences are decodes
for i in range(num_queries):
seq_group = sampling_metadata.seq_groups[i]
assert seq_group.is_prompt is False # No prompt
assert seq_group.prompt_logprob_indices == [] # No prompt
assert seq_group.sample_indices == [i] # Simple
assert seq_group.seq_len is None # Decode
assert seq_group.query_len is None # Decode
def _advance_step(self, model_input: StatefulModelInput,
out: SamplerOutput) -> StatefulModelInput:
model_input.maybe_advance_frozen_model_input(self.device,
self.pin_memory)
frozen_model_input = model_input.frozen_model_input
assert frozen_model_input is not None
assert frozen_model_input.input_tokens is not None
assert frozen_model_input.input_tokens.shape[0] == model_input.num_seqs
assert frozen_model_input.attn_metadata is not None
sampled_token_ids = model_input.cached_outputs[-1].sampled_token_ids
num_seqs = model_input.num_seqs
num_queries = model_input.num_queries
frozen_model_input = model_input.frozen_model_input
assert frozen_model_input is not None
attn_metadata = frozen_model_input.attn_metadata
assert attn_metadata is not None
turn_prefills_into_decodes: bool = model_input.current_step == 1 and \
model_input.num_single_step_prefills != 0
attn_metadata.advance_step(
frozen_model_input,
sampled_token_ids,
self.block_size,
num_seqs,
num_queries,
turn_prefills_into_decodes=turn_prefills_into_decodes)
return model_input
def load_model(self) -> None:
self._base_model_runner.load_model()
self.model_memory_usage = self._base_model_runner.model_memory_usage
def save_sharded_state(
self,
path: str,
pattern: Optional[str] = None,
max_size: Optional[int] = None,
) -> None:
return self._base_model_runner.save_sharded_state(
path, pattern, max_size)
def save_tensorized_model(self,
tensorizer_config: TensorizerConfig) -> None:
return self._base_model_runner.save_tensorized_model(tensorizer_config)
def profile_run(self) -> None:
return self._base_model_runner.profile_run()
def remove_all_loras(self):
return self._base_model_runner.remove_all_loras()
def capture_model(self, kv_caches: List[List]) -> None:
return self._base_model_runner.capture_model(kv_caches)
@property
def vocab_size(self) -> int:
return self._base_model_runner.vocab_size
DeferredLogprobsReturnType = Tuple[Optional[List[Optional[PromptLogprobs]]],
Optional[List[SampleLogprobs]]]
def deferred_pythonize_logprobs(
output: SamplerOutput,
sampling_metadata: SamplingMetadata,
logprobs_tensor: Optional[torch.Tensor],
) -> DeferredLogprobsReturnType:
"""Perform deferred logprob Pythonization.
1. Pythonize NPU-side sampler result tensors into CPU-side sampler result.
2. Pythonize NPU-side logprobs tensor into CPU-side logprobs lists,
utilizing the Pythonized sampler result computed in step 1.
These deferred computations are not required for single-step scheduling
or the `profile_run()` phase of multi-step scheduling.
Args:
output: sampler output (under deferred Pythonization)
sampling_metadata
Returns:
prompt_logprobs (CPU), sample_logprobs (CPU)
"""
# - Deferred pythonization of sample result
sampler_result = get_pythonized_sample_results(
output.deferred_sample_results_args)
# - Erase the NPU-side deferred sample_result
# computation args to ensure it is never
# pythonized or transferred to CPU
output.deferred_sample_results_args = None
# - Deferred pythonization of logprobs
(
prompt_logprobs,
sample_logprobs,
) = get_logprobs(logprobs_tensor, sampling_metadata, sampler_result)
assert len(prompt_logprobs) == len(sampling_metadata.seq_groups)
assert len(sample_logprobs) == len(sampling_metadata.seq_groups)
return prompt_logprobs, sample_logprobs
def _pythonize_sampler_output(
model_input: StatefulModelInput,
output: SamplerOutput,
pinned_sampled_token_buffer: torch.Tensor,
sampled_token_ids: torch.Tensor,
logprobs_tensor: Optional[torch.Tensor],
cache: Optional[PythonizationCache],
) -> None:
""" This function is only called when the output tensors are ready.
See :class:`ModelOutput`.
Modifies `output.outputs` and `pinned_sampled_token_buffer` in-place,
adding a Pythonized output data structure
(:class:`CompletionSequenceGroupOutput`) for each :class:`SequenceGroup`.
Args:
model_input
output: sampler output
pinned_sampled_token_token_buffer: CPU-side pinned memory
(receives copy of
NPU-side token buffer.)
sampled_token_ids: NPU-side token buffer
logprobs_tensor: NPU-side tensor containing
logprobs computed during sampling
"""
assert model_input.frozen_model_input is not None
frozen_model_input = model_input.frozen_model_input
assert frozen_model_input.sampling_metadata is not None
sampling_metadata = frozen_model_input.sampling_metadata
# samples generation should have been skipped
assert not output.outputs
pinned_buffer = pinned_sampled_token_buffer[:model_input.num_queries]
# We guarantee output tensors are ready, so it is safe to
# pythonize the sampler output & obtain CPU-side logprobs.
#
# However we should check whether logprobs pythonization may
# be skipped entirely, i.e. because no logprobs were requested
# or pythonization was not deferred. To that end,
#
# * `prompt_logprobs_are_requested_for_prefill` signals that
# there are *any* prefill-phase requests which specify that
# prompt logprobs should be returned.
#
# * `any_logprobs_are_requested` signals that there are any
# requests which (1) specify that sample logprobs should be
# returned, or (2) are in the prefill phase AND specify that
# prompt logprobs should be returned.
#
# Later on, these flags cause adjustments to the pythonization
# process to accommodate logprobs.
seq_groups = sampling_metadata.seq_groups
prompt_logprobs_are_requested_for_prefill = any([
sg.sampling_params.prompt_logprobs is not None and sg.is_prompt
for sg in seq_groups
])
any_logprobs_are_requested = (
prompt_logprobs_are_requested_for_prefill
or any([sg.sampling_params.logprobs is not None for sg in seq_groups]))
if prompt_logprobs_are_requested_for_prefill:
# CPU NPU sync, after gathering *only* sampled tokens (since
# requesting prompt logprobs leads `sampled_token_ids` to
# include prompt token ids in addition to sampled token ids.)
sample_idx_tensor = torch.tensor(
[sdx for sg in seq_groups for sdx in sg.sample_indices])
pinned_buffer = pinned_buffer.copy_(
sampled_token_ids[sample_idx_tensor, :], non_blocking=False)
else:
# CPU NPU sync
pinned_buffer = pinned_buffer.copy_(sampled_token_ids,
non_blocking=False)
# this will not block as the tensors are already on CPU
samples_list = pinned_buffer.tolist()
skip_sampler_cpu_output = (
frozen_model_input.sampling_metadata.skip_sampler_cpu_output)
# *Don't* skip logprobs pythonization *if*:
# * Any requests require logprobs to be returned in this
# iteration AND
# * These requests are being scheduled in a fashion which
# defers pythonization (i.e. multi-step scheduling.)
do_pythonize_logprobs = (skip_sampler_cpu_output
and any_logprobs_are_requested)
(
prompt_logprobs,
sample_logprobs,
) = (deferred_pythonize_logprobs(output, sampling_metadata,
logprobs_tensor)
if do_pythonize_logprobs else (None, None))
for sgdx, (seq_group,
sample_result) in enumerate(zip(seq_groups, samples_list)):
# Reminder: Please update docs/source/features/compatibility_matrix.md
# If the feature combo become valid
# (Check for Guided Decoding)
if seq_group.sampling_params.logits_processors:
assert len(seq_group.sampling_params.logits_processors) == 0, (
"Logits Processors are not supported in multi-step decoding")
if do_pythonize_logprobs:
assert prompt_logprobs is not None
assert sample_logprobs is not None
(
group_prompt_logprobs,
group_sample_logprobs,
) = ( # Utilize deferred pythonization results
prompt_logprobs[sgdx],
sample_logprobs[sgdx],
)
elif any_logprobs_are_requested:
(
group_prompt_logprobs,
group_sample_logprobs,
) = (
# profile_run: use already-computed logprobs
output.outputs[sgdx].prompt_logprobs,
[sample.logprobs for sample in output.outputs[sgdx].samples])
seq_ids = seq_group.seq_ids
next_token_ids = sample_result
parent_ids = [0]
seq_outputs: List[SequenceOutput]
if cache is not None:
completion_seq_group_output: CompletionSequenceGroupOutput = \
cache.cached_completion_seq_group_output.get_object()
completion_seq_group_output.samples.clear()
seq_outputs = completion_seq_group_output.samples
else:
seq_outputs = []
for tdx, (parent_id,
next_token_id) in enumerate(zip(parent_ids, next_token_ids)):
if cache is not None:
seq_output: SequenceOutput = cache.cached_seq_output.get_object(
)
seq_output.parent_seq_id = seq_ids[parent_id]
seq_output.output_token = next_token_id
if any_logprobs_are_requested:
seq_output.logprobs = group_sample_logprobs[tdx]
else:
logprobs = next(iter(seq_output.logprobs.values()))
seq_output.logprobs.clear()
logprobs.logprob = float('inf')
logprobs.rank = None
logprobs.decoded_token = None
seq_output.logprobs[next_token_id] = logprobs
seq_outputs.append(seq_output)
else:
seq_outputs.append(
SequenceOutput(seq_ids[parent_id], next_token_id,
(group_sample_logprobs[tdx]
if any_logprobs_are_requested else {
next_token_id:
Logprob(logprob=float('inf'),
rank=None,
decoded_token=None)
})))
if cache is not None:
completion_seq_group_output.prompt_logprobs = \
group_prompt_logprobs if any_logprobs_are_requested else None
output.outputs.append(completion_seq_group_output)
else:
output.outputs.append(
CompletionSequenceGroupOutput(
seq_outputs, (group_prompt_logprobs
if any_logprobs_are_requested else None)))
assert len(output.outputs) > 0