leiwen83 b38e42fbca
[Speculative decoding] Add ngram prompt lookup decoding (#4237)
Co-authored-by: Lei Wen <wenlei03@qiyi.com>
2024-05-01 11:13:03 -07:00

136 lines
4.5 KiB
Python

from contextlib import contextmanager
from itertools import chain
from typing import List, Tuple
import torch
from vllm.sequence import SamplerOutput, SequenceGroupMetadata
SeqId = int
def get_all_seq_ids(
seq_group_metadata_list: List[SequenceGroupMetadata]) -> List[SeqId]:
"""Given a list of SequenceGroupMetadata, create a list of all
sequence ids.
"""
return list(
chain.from_iterable([
seq_group_metadata.seq_data.keys()
for seq_group_metadata in seq_group_metadata_list
]))
def split_batch_by_proposal_len(
seq_group_metadata_list: List[SequenceGroupMetadata],
proposal_lens: List[int], select_proposal_len_zero: bool
) -> Tuple[List[SequenceGroupMetadata], List[int]]:
"""Utility function that splits a batch based on whether the proposal len is
zero or not. We should remove this once vLLM supports per-sequence proposal
lens in a batch.
"""
if select_proposal_len_zero:
predicate = lambda proposal_len: proposal_len == 0
else:
predicate = lambda proposal_len: proposal_len != 0
indices = [
i for i, (_, proposal_len
) in enumerate(zip(seq_group_metadata_list, proposal_lens))
if predicate(proposal_len)
]
seq_groups = [
seq_group for seq_group, proposal_len in zip(
seq_group_metadata_list, proposal_lens) if predicate(proposal_len)
]
return seq_groups, indices
def sampler_output_to_torch(
sampler_output_list: List[SamplerOutput],
sampler_transposed: bool) -> Tuple[torch.Tensor, torch.Tensor]:
"""Utility function which converts a list of SamplerOutput to tensors.
sampler_transposed here is used as the indicator for whether
we need do additional tensor transpose logic here.
Returns:
sampled_token_ids: torch.Tensor
shape: [batch_size, len(sampler_output_list)]
sampled_token_probs: torch.Tensor
shape: [batch_size, len(sampler_output_list), vocab_size]
"""
# shape: [batch_size, num_sampler_output, vocab_size]
sampled_token_probs = torch.stack(
[
sampler_output.sampled_token_probs
for sampler_output in sampler_output_list
],
dim=0,
)
if sampler_transposed:
sampled_token_probs = sampled_token_probs.transpose(0, 1)
# shape: [batch_size, num_sampler_output]
sampled_token_ids = torch.stack(
[
sampler_output.sampled_token_ids.flatten()
for sampler_output in sampler_output_list
],
dim=0,
)
if sampler_transposed:
sampled_token_ids = sampled_token_ids.transpose(0, 1)
return sampled_token_ids, sampled_token_probs
def maybe_mock_device_tensors(sampler_output: SamplerOutput, batch_size: int,
vocab_size: int, device: str) -> None:
"""Helper method which mocks out the GPU tensors in SamplerOutput with dummy
values. This will be removed in PR 7/9.
https://docs.google.com/document/d/1rE4pr3IdspRw97XbImY4fS9IWYuJJ3HGtL7AdIKGrw8/edit#heading=h.qijw1sdidrer
"""
values = [
sampler_output.sampled_token_probs, sampler_output.sampled_token_ids
]
assert all(v is None for v in values) or not any(v is None for v in values)
if not any(v is None for v in values):
# Do nothing if the tensors are already created (usually in unit tests).
return
# Softmax to ensure valid probs.
sampler_output.sampled_token_probs = torch.nn.functional.softmax(
torch.rand(batch_size, vocab_size, dtype=torch.float32, device=device),
dim=-1)
sampler_output.sampled_token_ids = torch.randint(low=10,
high=100,
size=(batch_size, ),
dtype=torch.long,
device=device)
@contextmanager
def nvtx_range(msg, *args, **kwargs):
"""
Context manager / decorator that pushes an NVTX range at the beginning
of its scope, and pops it at the end. If extra arguments are given,
they are passed as arguments to msg.format().
If running with cuda graphs, you must enable nsys cuda graph profiling.
Arguments:
msg (string): message to associate with the range
"""
torch.cuda.nvtx.range_push(msg.format(*args, **kwargs))
try:
yield
finally:
torch.cuda.nvtx.range_pop()