Files
sglang/python/sglang/srt/mem_cache/chunk_cache.py
Hanming Lu 9379da77de SWA Prefix Cache (#7367)
Co-authored-by: Ying Sheng <sqy1415@gmail.com>
2025-07-13 12:31:07 -07:00

101 lines
3.1 KiB
Python

from __future__ import annotations
"""Cache for chunked prefill, used when RadixCache is disabled."""
from typing import TYPE_CHECKING, Any, Callable, List, Optional, Tuple
import torch
from sglang.srt.mem_cache.allocator import (
BaseTokenToKVPoolAllocator,
SWATokenToKVPoolAllocator,
)
from sglang.srt.mem_cache.base_prefix_cache import BasePrefixCache, MatchResult
from sglang.srt.mem_cache.memory_pool import ReqToTokenPool
if TYPE_CHECKING:
from sglang.srt.managers.schedule_batch import Req
class ChunkCache(BasePrefixCache):
def __init__(
self,
req_to_token_pool: ReqToTokenPool,
token_to_kv_pool_allocator: BaseTokenToKVPoolAllocator,
page_size: int,
):
self.req_to_token_pool = req_to_token_pool
self.token_to_kv_pool_allocator = token_to_kv_pool_allocator
self.page_size = page_size
def reset(self):
pass
def match_prefix(self, **unused_kwargs) -> MatchResult:
return MatchResult(
device_indices=torch.empty((0,), dtype=torch.int64),
last_device_node=None,
last_host_node=None,
)
def cache_finished_req(self, req: Req):
kv_indices = self.req_to_token_pool.req_to_token[
req.req_pool_idx,
# For decode server: if req.output_ids is empty, we want to free all req.origin_input_ids
: len(req.origin_input_ids) + max(len(req.output_ids) - 1, 0),
]
self.req_to_token_pool.free(req.req_pool_idx)
self.token_to_kv_pool_allocator.free(kv_indices)
def cache_unfinished_req(self, req: Req):
kv_indices = self.req_to_token_pool.req_to_token[
req.req_pool_idx, : len(req.fill_ids)
]
# `req.prefix_indices` will be used in `PrefillAdder::add_chunked_req` later
req.prefix_indices = kv_indices
def evict(self, num_tokens: int):
pass
def inc_lock_ref(self, node: Any):
return 0
def dec_lock_ref(self, node: Any, swa_uuid_for_lock: Optional[str] = None):
return 0
def pretty_print(self):
return ""
class SWAChunkCache(ChunkCache):
"""ChunkCache with support for hybrid KV cache operations."""
def __init__(
self,
req_to_token_pool: ReqToTokenPool,
token_to_kv_pool_allocator: SWATokenToKVPoolAllocator,
page_size: int,
):
super().__init__(req_to_token_pool, token_to_kv_pool_allocator, page_size)
assert isinstance(token_to_kv_pool_allocator, SWATokenToKVPoolAllocator)
def evict_swa(
self,
req: Req,
prelen: int,
attention_chunk_size: int,
):
if prelen >= req.evicted_seqlen_local + attention_chunk_size:
new_evicted_seqlen_local = attention_chunk_size * (
prelen // attention_chunk_size
)
free_slots = self.req_to_token_pool.req_to_token[
req.req_pool_idx, req.evicted_seqlen_local : new_evicted_seqlen_local
]
self.token_to_kv_pool_allocator.free_swa(free_slots)
req.evicted_seqlen_local = new_evicted_seqlen_local
def evict(self, num_tokens: int):
pass