mirror of
https://git.datalinker.icu/vllm-project/vllm.git
synced 2025-12-10 04:54:56 +08:00
ac201a0eaf
Signed-off-by: hongchao <hongchao@msh.team> Signed-off-by: youkaichao <youkaichao@gmail.com> Co-authored-by: hongchao <hongchao@msh.team> Co-authored-by: youkaichao <youkaichao@gmail.com>
399 lines
16 KiB
Python
399 lines
16 KiB
Python
# SPDX-License-Identifier: Apache-2.0
|
||
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
|
||
|
||
from dataclasses import dataclass
|
||
from typing import Literal, Optional, overload
|
||
|
||
from vllm.distributed.kv_events import KVCacheEvent
|
||
from vllm.logger import init_logger
|
||
from vllm.v1.core.kv_cache_coordinator import get_kv_cache_coordinator
|
||
from vllm.v1.core.kv_cache_utils import KVCacheBlock
|
||
from vllm.v1.kv_cache_interface import KVCacheConfig
|
||
from vllm.v1.metrics.stats import PrefixCacheStats
|
||
from vllm.v1.request import Request, RequestStatus
|
||
|
||
logger = init_logger(__name__)
|
||
|
||
|
||
@dataclass
|
||
class KVCacheBlocks:
|
||
"""
|
||
The allocation result of KVCacheManager, work as the interface between
|
||
Scheduler and KVCacheManager, to hide KVCacheManager's internal data
|
||
structure from the Scheduler.
|
||
"""
|
||
blocks: tuple[list[KVCacheBlock], ...]
|
||
"""
|
||
blocks[i][j] refers to the i-th kv_cache_group and the j-th block of tokens.
|
||
We don't use block of tokens as the outer dimension because it assumes all
|
||
kv_cache_groups have the same number of blocks, which is true for now but
|
||
will be broken if we want to give different block_size to different
|
||
kv_cache_groups in the future.
|
||
"""
|
||
|
||
def __add__(self, other: "KVCacheBlocks") -> "KVCacheBlocks":
|
||
"""Adds two KVCacheBlocks instances."""
|
||
return KVCacheBlocks(
|
||
tuple(blk1 + blk2
|
||
for blk1, blk2 in zip(self.blocks, other.blocks)))
|
||
|
||
@overload
|
||
def get_block_ids(
|
||
self,
|
||
allow_none: Literal[False] = False,
|
||
) -> tuple[list[int], ...]:
|
||
...
|
||
|
||
@overload
|
||
def get_block_ids(
|
||
self,
|
||
allow_none: Literal[True] = True,
|
||
) -> Optional[tuple[list[int], ...]]:
|
||
...
|
||
|
||
def get_block_ids(
|
||
self,
|
||
allow_none: bool = False,
|
||
) -> Optional[tuple[list[int], ...]]:
|
||
"""
|
||
Converts the KVCacheBlocks instance to block_ids.
|
||
|
||
Returns:
|
||
tuple[list[int], ...]: A tuple of lists where:
|
||
- the outer tuple corresponds to KV cache groups
|
||
- each inner list contains the block_ids of the blocks in that
|
||
group
|
||
"""
|
||
if allow_none and all(len(group) == 0 for group in self.blocks):
|
||
return None
|
||
return tuple([blk.block_id for blk in group] for group in self.blocks)
|
||
|
||
def get_unhashed_block_ids(self) -> list[int]:
|
||
"""Get block_ids of unhashed blocks from KVCacheBlocks instance."""
|
||
assert len(self.blocks) == 1, "Only one group is supported"
|
||
return [
|
||
block.block_id for block in self.blocks[0]
|
||
if block.block_hash is None
|
||
]
|
||
|
||
def new_empty(self) -> "KVCacheBlocks":
|
||
"""Creates a new KVCacheBlocks instance with no blocks."""
|
||
return KVCacheBlocks(tuple([] for _ in range(len(self.blocks))))
|
||
|
||
|
||
class KVCacheManager:
|
||
|
||
def __init__(
|
||
self,
|
||
kv_cache_config: KVCacheConfig,
|
||
max_model_len: int,
|
||
enable_caching: bool = True,
|
||
use_eagle: bool = False,
|
||
log_stats: bool = False,
|
||
enable_kv_cache_events: bool = False,
|
||
dcp_world_size: int = 1,
|
||
) -> None:
|
||
self.max_model_len = max_model_len
|
||
|
||
self.enable_caching = enable_caching
|
||
self.use_eagle = use_eagle
|
||
self.log_stats = log_stats
|
||
# FIXME: make prefix cache stats conditional on log_stats
|
||
self.prefix_cache_stats = PrefixCacheStats() if log_stats else None
|
||
|
||
self.block_size: Optional[int] = None
|
||
if self.enable_caching:
|
||
assert len(
|
||
set(g.kv_cache_spec.block_size
|
||
for g in kv_cache_config.kv_cache_groups)
|
||
) == 1, "Only one block size is supported for now"
|
||
self.block_size = kv_cache_config.kv_cache_groups[
|
||
0].kv_cache_spec.block_size
|
||
|
||
if dcp_world_size > 1:
|
||
assert len(kv_cache_config.kv_cache_groups) == 1
|
||
# Note(hc): need revisit. When both DCP and any future
|
||
# PCP are enabled, the block_size may need to be scaled
|
||
# by a factor of dcp_size × pcp_size?
|
||
self.block_size *= dcp_world_size
|
||
|
||
self.coordinator = get_kv_cache_coordinator(
|
||
kv_cache_config=kv_cache_config,
|
||
max_model_len=self.max_model_len,
|
||
use_eagle=self.use_eagle,
|
||
enable_caching=self.enable_caching,
|
||
enable_kv_cache_events=enable_kv_cache_events,
|
||
dcp_world_size=dcp_world_size,
|
||
)
|
||
self.num_kv_cache_groups = len(kv_cache_config.kv_cache_groups)
|
||
self.block_pool = self.coordinator.block_pool
|
||
self.kv_cache_config = kv_cache_config
|
||
|
||
@property
|
||
def usage(self) -> float:
|
||
"""Get the KV cache usage.
|
||
|
||
Returns:
|
||
The KV cache usage (between 0.0 and 1.0).
|
||
"""
|
||
return self.block_pool.get_usage()
|
||
|
||
def make_prefix_cache_stats(self) -> Optional[PrefixCacheStats]:
|
||
"""Get (and reset) the prefix cache stats.
|
||
|
||
Returns:
|
||
The current prefix caching stats, or None if logging is disabled.
|
||
"""
|
||
if not self.log_stats:
|
||
return None
|
||
stats = self.prefix_cache_stats
|
||
self.prefix_cache_stats = PrefixCacheStats()
|
||
return stats
|
||
|
||
def get_computed_blocks(self,
|
||
request: Request) -> tuple[KVCacheBlocks, int]:
|
||
"""Get the computed (cached) blocks for the request.
|
||
Note that the computed blocks must be full.
|
||
|
||
Args:
|
||
request: The request to get the computed blocks.
|
||
|
||
Returns:
|
||
A tuple containing:
|
||
- A list of blocks that are computed for the request.
|
||
- The number of computed tokens.
|
||
"""
|
||
# Prefix caching is disabled or
|
||
# When the request requires prompt logprobs, we skip prefix caching.
|
||
if (not self.enable_caching
|
||
or (request.sampling_params is not None
|
||
and request.sampling_params.prompt_logprobs is not None)):
|
||
return self.create_empty_block_list(), 0
|
||
|
||
# NOTE: When all tokens hit the cache, we must recompute the last token
|
||
# to obtain logits. Thus, set max_cache_hit_length to prompt_length - 1.
|
||
# This can trigger recomputation of an entire block, rather than just
|
||
# the single last token, because allocate_slots() requires
|
||
# num_computed_tokens to be block-size aligned. Removing this limitation
|
||
# could slightly improve performance in the future.
|
||
max_cache_hit_length = request.num_tokens - 1
|
||
computed_blocks, num_new_computed_tokens = (
|
||
self.coordinator.find_longest_cache_hit(request.block_hashes,
|
||
max_cache_hit_length))
|
||
|
||
if self.log_stats:
|
||
assert self.prefix_cache_stats is not None
|
||
self.prefix_cache_stats.requests += 1
|
||
self.prefix_cache_stats.queries += request.num_tokens
|
||
self.prefix_cache_stats.hits += num_new_computed_tokens
|
||
|
||
return KVCacheBlocks(computed_blocks), num_new_computed_tokens
|
||
|
||
def allocate_slots(
|
||
self,
|
||
request: Request,
|
||
num_new_tokens: int,
|
||
num_new_computed_tokens: int = 0,
|
||
new_computed_blocks: Optional[KVCacheBlocks] = None,
|
||
num_lookahead_tokens: int = 0,
|
||
delay_cache_blocks: bool = False,
|
||
num_encoder_tokens: int = 0,
|
||
) -> Optional[KVCacheBlocks]:
|
||
"""Add slots for a request with new tokens to append.
|
||
|
||
Args:
|
||
request: The request to allocate slots.
|
||
num_new_tokens: The number of tokens to allocate, including external
|
||
tokens. Note that this does not include tokens that have
|
||
already been computed locally (i.e. new_computed_blocks).
|
||
num_new_computed_tokens: The number of new computed tokens just
|
||
hitting the prefix caching, excluding external tokens.
|
||
new_computed_blocks: The cached blocks for the above new computed
|
||
tokens.
|
||
num_lookahead_tokens: The number of speculative tokens to allocate.
|
||
This is used by spec decode proposers with kv-cache such
|
||
as eagle.
|
||
delay_cache_blocks: Whether to skip caching the blocks. This is
|
||
used by P/D when allocating blocks used in a KV transfer
|
||
which will complete in a future step.
|
||
|
||
Blocks layout:
|
||
```
|
||
-----------------------------------------------------------------------
|
||
| < computed > | < new computed > | < new > | < pre-allocated > |
|
||
-----------------------------------------------------------------------
|
||
| < required > |
|
||
--------------------------------------------------
|
||
| < full > |
|
||
------------------------------------------------
|
||
| <new full> |
|
||
--------------
|
||
```
|
||
The following *_blocks are illustrated in this layout.
|
||
|
||
Returns:
|
||
A list of new allocated blocks.
|
||
"""
|
||
if num_new_tokens == 0:
|
||
raise ValueError("num_new_tokens must be greater than 0")
|
||
|
||
if new_computed_blocks is not None:
|
||
new_computed_block_list = new_computed_blocks.blocks
|
||
else:
|
||
new_computed_block_list = tuple(
|
||
[] for _ in range(len(self.kv_cache_config.kv_cache_groups)))
|
||
|
||
# Free the blocks that are skipped during the attention computation
|
||
# (e.g., tokens outside the sliding window).
|
||
# We can do this even if we cannot schedule this request due to
|
||
# insufficient free blocks.
|
||
# Should call this function before allocating new blocks to reduce
|
||
# the number of evicted blocks.
|
||
self.coordinator.remove_skipped_blocks(request.request_id,
|
||
request.num_computed_tokens)
|
||
|
||
# The number of computed tokens is the number of computed tokens plus
|
||
# the new prefix caching hits
|
||
num_computed_tokens = (request.num_computed_tokens +
|
||
num_new_computed_tokens)
|
||
num_tokens_need_slot = min(
|
||
num_computed_tokens + num_new_tokens + num_lookahead_tokens,
|
||
self.max_model_len)
|
||
|
||
num_blocks_to_allocate = self.coordinator.get_num_blocks_to_allocate(
|
||
request_id=request.request_id,
|
||
num_tokens=num_tokens_need_slot,
|
||
new_computed_blocks=new_computed_block_list,
|
||
num_encoder_tokens=num_encoder_tokens,
|
||
)
|
||
|
||
if num_blocks_to_allocate > self.block_pool.get_num_free_blocks():
|
||
# Cannot allocate new blocks
|
||
return None
|
||
|
||
# Touch the computed blocks to make sure they won't be evicted.
|
||
if self.enable_caching:
|
||
self.block_pool.touch(new_computed_block_list)
|
||
else:
|
||
assert not any(new_computed_block_list), (
|
||
"Computed blocks should be empty when "
|
||
"prefix caching is disabled")
|
||
|
||
# Append the new computed blocks to the request blocks until now to
|
||
# avoid the case where the new blocks cannot be allocated.
|
||
self.coordinator.save_new_computed_blocks(request.request_id,
|
||
new_computed_block_list)
|
||
|
||
new_blocks = self.coordinator.allocate_new_blocks(
|
||
request.request_id, num_tokens_need_slot, num_encoder_tokens)
|
||
|
||
# P/D: delay caching blocks if we have to recv from
|
||
# remote. Update state for locally cached blocks.
|
||
if not self.enable_caching or delay_cache_blocks:
|
||
return KVCacheBlocks(new_blocks)
|
||
|
||
# NOTE(woosuk): We want to commit (cache) up to num_computed_tokens +
|
||
# num_new_tokens, but must exclude "non-committable" tokens (e.g.,
|
||
# draft tokens that could be rejected). Therefore, we cap the number
|
||
# at `request.num_tokens`, ensuring only "finalized" tokens are cached.
|
||
num_tokens_to_cache = min(num_computed_tokens + num_new_tokens,
|
||
request.num_tokens)
|
||
self.coordinator.cache_blocks(request, num_tokens_to_cache)
|
||
|
||
return KVCacheBlocks(new_blocks)
|
||
|
||
def free(self, request: Request) -> None:
|
||
"""Free the blocks allocated for the request.
|
||
We free the blocks in reverse order so that the tail blocks are evicted
|
||
first when caching is enabled.
|
||
|
||
Args:
|
||
request: The request to free the blocks.
|
||
"""
|
||
self.coordinator.free(request.request_id)
|
||
|
||
def reset_prefix_cache(self) -> bool:
|
||
"""Reset prefix cache. This function may be used in RLHF
|
||
flows to invalidate prefix caching after the weights are updated,
|
||
or used for resetting prefix caching status for benchmarking.
|
||
|
||
Returns:
|
||
bool: True if the prefix cache is successfully reset,
|
||
False otherwise.
|
||
"""
|
||
if not self.block_pool.reset_prefix_cache():
|
||
return False
|
||
if self.log_stats:
|
||
assert self.prefix_cache_stats is not None
|
||
self.prefix_cache_stats.reset = True
|
||
return True
|
||
|
||
def get_num_common_prefix_blocks(
|
||
self,
|
||
request: Request,
|
||
num_running_requests: int,
|
||
) -> list[int]:
|
||
"""Calculate the number of common prefix blocks shared by all requests
|
||
in the RUNNING state for each kv cache group.
|
||
|
||
The function determines this by selecting any request and iterating
|
||
through its blocks. A block is considered a common prefix block if its
|
||
`ref_cnt` equals the total number of requests in the RUNNING state.
|
||
|
||
NOTE(woosuk): The number of requests in the RUNNING state is **greater
|
||
than or equal to** the number of requests scheduled in the current step.
|
||
This is because the RUNNING state only indicates that:
|
||
1. The request has not yet finished, and
|
||
2. The request holds its blocks unfreed.
|
||
|
||
While all scheduled requests must be in the RUNNING state, the inverse
|
||
is not necessarily true. There may be RUNNING requests that are not
|
||
scheduled in the current step.
|
||
|
||
This can result in an edge case where the number of common prefix blocks
|
||
is 0, even though all scheduled requests share a common prefix. This
|
||
occurs because there may be unscheduled RUNNING requests that do not
|
||
share the common prefix. Currently, this case cannot be easily detected,
|
||
so the function returns 0 in such cases.
|
||
|
||
Args:
|
||
request: Any request in the RUNNING state, used to identify the
|
||
common prefix blocks.
|
||
num_running_requests: The total number of requests in the RUNNING
|
||
state. This can be different from the number of scheduled
|
||
requests in the current step.
|
||
|
||
Returns:
|
||
list[int]: The number of common prefix blocks for each kv cache
|
||
group.
|
||
"""
|
||
assert request.status == RequestStatus.RUNNING
|
||
return self.coordinator.get_num_common_prefix_blocks(
|
||
request.request_id, num_running_requests)
|
||
|
||
def take_events(self) -> list[KVCacheEvent]:
|
||
"""Take the KV cache events from the block pool.
|
||
|
||
Returns:
|
||
A list of KV cache events.
|
||
"""
|
||
return self.block_pool.take_events()
|
||
|
||
def get_blocks(self, request_id: str) -> KVCacheBlocks:
|
||
"""Get the blocks of a request."""
|
||
return KVCacheBlocks(self.coordinator.get_blocks(request_id))
|
||
|
||
def get_block_ids(self, request_id: str) -> tuple[list[int], ...]:
|
||
"""Get the block ids of a request."""
|
||
return self.get_blocks(request_id).get_block_ids()
|
||
|
||
def cache_blocks(self, request: Request, num_computed_tokens: int) -> None:
|
||
"""Cache the blocks for the request, if enabled."""
|
||
if self.enable_caching:
|
||
self.coordinator.cache_blocks(request, num_computed_tokens)
|
||
|
||
def create_empty_block_list(self) -> KVCacheBlocks:
|
||
"""Creates a new KVCacheBlocks instance with no blocks."""
|
||
return KVCacheBlocks(tuple([]
|
||
for _ in range(self.num_kv_cache_groups)))
|