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enginex-hygon-vllm/vllm/attention/backends/tree_decoding_utils.py

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2026-01-09 15:09:53 +08:00
from typing import TYPE_CHECKING, Any, Dict, List, Type, TypeVar, Union, Optional
import torch
from vllm.attention.backends.blocksparse_attn import BlocksparseFlashAttentionImpl
from vllm import _custom_ops as ops
from vllm.attention.ops.paged_attn import PagedAttention
def move_cache(
backend,
kv_caches: List[torch.Tensor],
src_to_dists: torch.Tensor,
kv_cache_dtype: str,
num_kv_heads: int,
head_size: int,
) -> None:
if backend.get_name() == "rocm-flash-attn" or \
backend.get_name() == "xformers":
key_caches = []
value_caches = []
num_layers = len(kv_caches)
token_num = src_to_dists.shape[0]
tmp_store_kv = torch.empty(
(2, num_layers, token_num, num_kv_heads, head_size),
dtype=kv_caches[0].dtype, device=kv_caches[0].device)
keys = tmp_store_kv[0].contiguous()
values = tmp_store_kv[1].contiguous()
for kv_cache in kv_caches:
key_cache, value_cache = PagedAttention.split_kv_cache(
kv_cache, num_kv_heads, head_size)
key_caches.append(key_cache)
value_caches.append(value_cache)
ops.read_cache(
keys,
values,
key_caches,
value_caches,
src_to_dists[:, 0].contiguous(),
kv_cache_dtype
)
ops.write_cache_multi_layers(
keys,
values,
key_caches,
value_caches,
src_to_dists[:, 1].contiguous(),
kv_cache_dtype
)
else:
raise NotImplementedError("Only BlocksparseFlashAttention/ROCmFlash/XFormers backends support move cache for now!")