Matthew Bonanni fc1d8be3dc
[Attention] Update attention imports (#29540)
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
2025-11-27 11:19:09 -05:00

69 lines
2.4 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from abc import abstractmethod
from collections.abc import Iterable
import torch
from vllm.attention.backends.abstract import AttentionBackend
from vllm.attention.selector import get_mamba_attn_backend
from vllm.config import VllmConfig
from vllm.model_executor.layers.attention_layer_base import AttentionLayerBase
from vllm.v1.kv_cache_interface import KVCacheSpec, MambaSpec
class MambaBase(AttentionLayerBase):
"""
Base class for Mamba-like layers which support the v1 engine.
Inherit from this class if you implement a custom layer.
"""
# Contains the KV cache (mamba state) for the layer
# in the shape specified by `self.get_state_shape`.
kv_cache: tuple[torch.Tensor, ...]
@abstractmethod
def get_state_shape(self) -> Iterable[tuple[int, ...]]:
"""
Defines the shape of the state.
For mamba layers this is usually a (conv_state, ssm_state) tuple.
In this case, returns (conv_state_shape, ssm_state_shape).
"""
pass
@property
@abstractmethod
def mamba_type(self) -> str:
pass
@abstractmethod
def get_state_dtype(self) -> tuple[torch.dtype, ...]:
pass
def get_kv_cache_spec(self, vllm_config: VllmConfig) -> KVCacheSpec | None:
if (
vllm_config.speculative_config is not None
and vllm_config.model_config.hf_config.model_type not in ["qwen3_next"]
):
raise NotImplementedError(
"Mamba with speculative decoding is not supported yet."
)
mamba_block_size = vllm_config.cache_config.mamba_block_size
page_size_padded = vllm_config.cache_config.mamba_page_size_padded
return MambaSpec(
shapes=self.get_state_shape(),
dtypes=self.get_state_dtype(),
block_size=mamba_block_size,
page_size_padded=page_size_padded,
mamba_type=self.mamba_type,
num_speculative_blocks=(
vllm_config.speculative_config.num_speculative_tokens
if vllm_config.speculative_config
else 0
),
)
def get_attn_backend(self) -> type[AttentionBackend]:
"""Get the attention backend class for this Mamba layer."""
return get_mamba_attn_backend(self.mamba_type)