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enginex-hygon-vllm/vllm/attention/backends/cpu_mla.py
2026-01-09 15:09:53 +08:00

308 lines
11 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from dataclasses import dataclass
from typing import Any, Dict, List, Optional, Tuple, Type
import torch
import vllm._custom_ops as ops
from vllm._ipex_ops import ipex_ops
from vllm.attention.backends.abstract import (AttentionBackend,
AttentionMetadataBuilder,
AttentionType,
is_quantized_kv_cache)
from vllm.attention.backends.mla.common import MLACommonImpl, MLACommonState
from vllm.attention.backends.torch_sdpa import TorchSDPAMetadata
from vllm.utils import make_tensor_with_pad
from vllm.worker.cpu_model_runner import ModelInputForCPUBuilder
class CPUMLABackend(AttentionBackend):
@staticmethod
def get_name() -> str:
return "CPU_MLA"
@staticmethod
def get_metadata_cls() -> Type["CPUMLAMetadata"]:
return CPUMLAMetadata
@staticmethod
def get_builder_cls() -> Type["CPUMLAMetadataBuilder"]:
return CPUMLAMetadataBuilder
@staticmethod
def get_state_cls() -> Type["MLACommonState"]:
return MLACommonState
@staticmethod
def get_impl_cls() -> Type["CPUMLAImpl"]:
return CPUMLAImpl
@staticmethod
def get_kv_cache_shape(
num_blocks: int,
block_size: int,
num_kv_heads: int, # assumed to be 1 for MLA
head_size: int,
) -> Tuple[int, ...]:
return (num_blocks, block_size, head_size)
@staticmethod
def swap_blocks(
src_kv_cache: torch.Tensor,
dst_kv_cache: torch.Tensor,
src_to_dst: torch.Tensor,
) -> None:
ops.swap_blocks(src_kv_cache, dst_kv_cache, src_to_dst)
@staticmethod
def copy_blocks(
kv_caches: List[torch.Tensor],
src_to_dists: torch.Tensor,
) -> None:
ops.copy_blocks_mla(kv_caches, src_to_dists)
@staticmethod
def get_supported_head_sizes() -> List[int]:
return [576]
@dataclass
class CPUMLAMetadata(TorchSDPAMetadata):
# New for MLA
# Input positions for rotrary embeddings since for MLA the rotary
# position embeddings are applied inside the attention backend
input_positions: torch.Tensor = None
# required by MLACommonImpl
is_profile_run: bool = False
class CPUMLAMetadataBuilder(AttentionMetadataBuilder[CPUMLAMetadata]):
def __init__(self, input_builder: ModelInputForCPUBuilder) -> None:
self.chunked_prefill = input_builder.chunked_prefill
self.input_builder = input_builder
assert not self.chunked_prefill, \
"chunked prefill is currently not supported"
def prepare(self):
self.input_data = self.input_builder.input_data
def build(self, seq_lens, query_lens, cuda_graph_pad_size, batch_size):
input_data = self.input_data
prefill_seq_lens = seq_lens[0:input_data.num_prefills]
prefill_query_lens = query_lens[0:input_data.num_prefills]
slot_mapping = torch.tensor(input_data.slot_mapping,
dtype=torch.long,
device="cpu")
# metadata for prefill
if input_data.num_prefills > 0:
query_lens_tensor = torch.tensor(prefill_query_lens,
dtype=torch.int32,
device="cpu")
kv_lens_tensor = torch.tensor(prefill_seq_lens,
dtype=torch.int32,
device="cpu")
query_start_loc = torch.zeros(input_data.num_prefills + 1,
dtype=torch.int32,
device="cpu")
kv_start_loc = torch.zeros(input_data.num_prefills + 1,
dtype=torch.int32,
device="cpu")
torch.cumsum(query_lens_tensor,
dim=0,
dtype=torch.int32,
out=query_start_loc[1:])
torch.cumsum(kv_lens_tensor,
dim=0,
dtype=torch.int32,
out=kv_start_loc[1:])
max_query_len = max(prefill_query_lens)
max_kv_len = max(prefill_seq_lens)
# for chunked-prefill
if self.chunked_prefill:
prefill_block_tables = make_tensor_with_pad(
self.input_data.prefill_block_tables,
pad=0,
dtype=torch.int32,
device="cpu",
)
else:
prefill_block_tables = None
else:
query_start_loc = None
kv_start_loc = None
max_query_len = None
max_kv_len = None
prefill_block_tables = None
# metadata for decode
if input_data.num_decode_tokens != 0:
seq_lens_tensor = torch.tensor(
input_data.seq_lens[input_data.num_prefills:],
dtype=torch.int32,
device="cpu",
)
block_tables = make_tensor_with_pad(
self.input_data.decode_block_tables,
pad=0,
dtype=torch.int32,
device="cpu",
)
else:
block_tables = torch.tensor([])
seq_lens_tensor = torch.tensor(
input_data.seq_lens[:input_data.num_prefills],
dtype=torch.int32,
device="cpu",
)
# For multi-modal models
placeholder_index_maps = None
if len(input_data.multi_modal_inputs_list) != 0:
placeholder_index_maps = {
modality: placeholder_map.index_map()
for modality, placeholder_map in
input_data.multi_modal_placeholder_maps.items()
}
return CPUMLAMetadata(
chunked_prefill=self.chunked_prefill,
seq_lens=prefill_seq_lens,
seq_lens_tensor=seq_lens_tensor,
max_query_len=max_query_len,
max_kv_len=max_kv_len,
prefill_query_start_loc=query_start_loc,
kv_start_loc=kv_start_loc,
max_decode_seq_len=input_data.max_decode_seq_len,
num_prefills=input_data.num_prefills,
num_prefill_tokens=input_data.num_prefill_tokens,
num_decode_tokens=input_data.num_decode_tokens,
block_tables=block_tables,
prefill_block_tables=prefill_block_tables,
slot_mapping=slot_mapping,
multi_modal_placeholder_index_maps=placeholder_index_maps,
enable_kv_scales_calculation=False,
input_positions=torch.tensor([self.input_data.input_positions]))
class CPUMLAImpl(MLACommonImpl[CPUMLAMetadata]):
def __init__(
self,
num_heads: int,
head_size: int,
scale: float,
num_kv_heads: int,
alibi_slopes: Optional[List[float]],
sliding_window: Optional[int],
kv_cache_dtype: str,
blocksparse_params: Optional[Dict[str, Any]],
logits_soft_cap: Optional[float],
attn_type: str,
kv_sharing_target_layer_name: Optional[str],
# MLA Specific Arguments
**mla_args) -> None:
super().__init__(num_heads, head_size, scale, num_kv_heads,
alibi_slopes, sliding_window, kv_cache_dtype,
blocksparse_params, logits_soft_cap, attn_type,
kv_sharing_target_layer_name, **mla_args)
unsupported_features = [
alibi_slopes, sliding_window, blocksparse_params, logits_soft_cap
]
if any(unsupported_features):
raise NotImplementedError(
"CPUMLAImpl does not support one of the following: "
"alibi_slopes, sliding_window, blocksparse_params, "
"logits_soft_cap")
if attn_type != AttentionType.DECODER:
raise NotImplementedError("Encoder self-attention and "
"encoder/decoder cross-attention "
"are not implemented for "
"CPUMLAImpl")
# states is implemented.
if is_quantized_kv_cache(self.kv_cache_dtype):
raise NotImplementedError(
"CPUMLAImpl with FP8 KV cache not yet supported")
def _forward_prefill(
self,
q: torch.Tensor,
kv_c_normed: torch.Tensor,
k_pe: torch.Tensor,
kv_c_and_k_pe_cache: torch.Tensor,
attn_metadata: CPUMLAMetadata, # type: ignore[override]
) -> torch.Tensor:
prefill_metadata = attn_metadata.prefill_metadata
assert prefill_metadata is not None
kv_nope = self.kv_b_proj(kv_c_normed)[0].view(\
-1, self.num_heads, self.qk_nope_head_dim + self.v_head_dim)
k_nope, v = kv_nope\
.split([self.qk_nope_head_dim, self.v_head_dim], dim=-1)
k = torch.cat((k_nope, k_pe.expand((*k_nope.shape[:-1], -1))), dim=-1)
# For MLA the v head dim is smaller than qk head dim so we pad out
# v with 0s to match the qk head dim
v_padded = torch.nn.functional.pad(v, [0, q.shape[-1] - v.shape[-1]],
value=0)
output = torch.empty_like(q)
ipex_ops.varlen_attention(
query=q,
key=k,
value=v_padded,
out=output,
seqlen_q=prefill_metadata.prefill_query_start_loc,
seqlen_k=prefill_metadata.prefill_query_start_loc,
max_seqlen_q=prefill_metadata.max_query_len,
max_seqlen_k=prefill_metadata.max_query_len,
pdropout=0.0,
softmax_scale=self.scale,
zero_tensors=False,
is_causal=True,
return_softmax=False,
gen_=None,
logits_soft_cap=0.0,
window_size_left=-1,
window_size_right=-1,
alibi_slopes=None,
)
# remove padding
output = output.view(-1, self.num_heads,
q.shape[-1])[..., :v.shape[-1]]
return output.reshape(-1, self.num_heads * v.shape[-1])
def _forward_decode(
self,
q_nope: torch.Tensor,
q_pe: torch.Tensor,
kv_c_and_k_pe_cache: torch.Tensor,
attn_metadata: CPUMLAMetadata, # type: ignore[override]
) -> torch.Tensor:
assert kv_c_and_k_pe_cache.numel() > 0
decode_meta = attn_metadata.decode_metadata
assert decode_meta is not None
q = torch.cat([q_nope, q_pe], dim=-1)
o = q.new_empty(q.shape[0], self.num_heads, self.kv_lora_rank)
# Run MQA
ops.mla_decode_kvcache_cpu(o, q, kv_c_and_k_pe_cache, self.scale,
decode_meta.block_tables,
decode_meta.seq_lens_tensor)
return self._v_up_proj(o)