Commit 2af8e008 authored by zhuwenwen's avatar zhuwenwen
Browse files

remove unused code

parent 993c31c3
# 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)
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
""" Attention layer with torch scaled_dot_product_attention
and PagedAttention."""
from dataclasses import dataclass
from typing import Any, Dict, List, Optional, Tuple, Type
import torch
from vllm._ipex_ops import ipex_ops
from vllm.attention.backends.abstract import (AttentionBackend, AttentionImpl,
AttentionLayer,
AttentionMetadata, AttentionType,
is_quantized_kv_cache)
from vllm.attention.backends.utils import CommonAttentionState
from vllm.attention.ops.paged_attn import (PagedAttention,
PagedAttentionMetadata)
from vllm.logger import init_logger
logger = init_logger(__name__)
_PARTITION_SIZE = 512
class IpexAttnBackend(AttentionBackend):
@staticmethod
def get_name() -> str:
return "IPEX"
@staticmethod
def get_impl_cls() -> Type["IpexAttnBackendImpl"]:
return IpexAttnBackendImpl
@staticmethod
def get_metadata_cls() -> Type["IpexAttnMetadata"]:
return IpexAttnMetadata
@staticmethod
def get_state_cls() -> Type["CommonAttentionState"]:
return CommonAttentionState
@staticmethod
def get_kv_cache_shape(
num_blocks: int,
block_size: int,
num_kv_heads: int,
head_size: int,
) -> Tuple[int, ...]:
return PagedAttention.get_kv_cache_shape(num_blocks, block_size,
num_kv_heads, head_size)
@staticmethod
def swap_blocks(
src_kv_cache: torch.Tensor,
dst_kv_cache: torch.Tensor,
src_to_dst: torch.Tensor,
) -> None:
from vllm._ipex_ops import ipex_ops as ops
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:
from vllm._ipex_ops import ipex_ops as ops
key_caches = [kv_cache[0] for kv_cache in kv_caches]
value_caches = [kv_cache[1] for kv_cache in kv_caches]
ops.copy_blocks(key_caches, value_caches, src_to_dists)
@dataclass
class IpexAttnMetadata(AttentionMetadata, PagedAttentionMetadata):
"""Metadata for IpexAttnBackend.
"""
# Currently, input sequences can only contain all prompts
# or all decoding. True if all sequences are prompts.
is_prompt: bool
slot_mapping: torch.Tensor
seq_lens: Optional[List[int]]
seqlen_q: Optional[torch.Tensor]
max_seqlen: Optional[int]
def __post_init__(self):
# Set during the execution of the first attention op.
# It is a list because it is needed to set per prompt
# when alibi slopes is used. It is because of the limitation
# from xformer API.
# will not appear in the __repr__ and __init__
self.attn_bias: Optional[List[torch.Tensor]] = None
@property
def prefill_metadata(self) -> Optional["IpexAttnMetadata"]:
# Currently chunked prefill is not supported
if self.num_decode_tokens == 0:
assert self.num_prefills > 0
return self
return None
@property
def decode_metadata(self) -> Optional["IpexAttnMetadata"]:
# Currently chunked prefill is not supported
if self.num_prefills > 0:
assert self.num_decode_tokens == 0
return None
return self
class IpexAttnBackendImpl(AttentionImpl[IpexAttnMetadata]):
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]] = None,
logits_soft_cap: Optional[float] = None,
attn_type: str = AttentionType.DECODER,
kv_sharing_target_layer_name: Optional[str] = None,
use_irope: bool = False,
) -> None:
if kv_sharing_target_layer_name is not None:
raise NotImplementedError("KV sharing is not supported in V0.")
if use_irope:
logger.warning_once(
"Using irope in Ipex is not supported yet, it will fall"
" back to global attention for long context.")
if blocksparse_params is not None:
raise ValueError(
"IPEX backend does not support block-sparse attention.")
self.num_heads = num_heads
self.head_size = head_size
self.scale = float(scale)
self.num_kv_heads = num_kv_heads
if alibi_slopes is not None:
alibi_slopes = torch.tensor(alibi_slopes, dtype=torch.float32)
self.alibi_slopes = alibi_slopes
self.sliding_window = sliding_window
self.kv_cache_dtype = kv_cache_dtype
self.num_queries_per_kv = self.num_heads // self.num_kv_heads
self.need_mask = (self.sliding_window is not None)
if logits_soft_cap is None:
logits_soft_cap = -1
self.logits_soft_cap = logits_soft_cap
supported_head_sizes = PagedAttention.get_supported_head_sizes()
if head_size not in supported_head_sizes:
raise ValueError(
f"Head size {head_size} is not supported by PagedAttention. "
f"Supported head sizes are: {supported_head_sizes}.")
if is_quantized_kv_cache(kv_cache_dtype):
raise NotImplementedError(
"IPEX backend does not support FP8 KV cache. "
"Please use xFormers backend instead.")
if attn_type != AttentionType.DECODER:
raise NotImplementedError("Encoder self-attention and "
"encoder/decoder cross-attention "
"are not implemented for "
"IpexAttnBackendImpl")
def split_kv_cache(
self,
kv_cache: torch.Tensor,
num_kv_heads: int,
head_size: int,
) -> Tuple[torch.Tensor, torch.Tensor]:
x = 1
num_blocks = kv_cache.shape[1]
key_cache = kv_cache[0]
key_cache = key_cache.view(num_blocks, num_kv_heads, head_size // x,
-1, x)
value_cache = kv_cache[1]
value_cache = value_cache.view(num_blocks, num_kv_heads, head_size, -1)
return key_cache, value_cache
def forward(
self,
layer: AttentionLayer,
query: torch.Tensor,
key: torch.Tensor,
value: torch.Tensor,
kv_cache: torch.Tensor,
attn_metadata: IpexAttnMetadata, # type: ignore
output: Optional[torch.Tensor] = None,
output_scale: Optional[torch.Tensor] = None,
) -> torch.Tensor:
"""Forward pass with IPEX varlen_attention and PagedAttention.
Args:
query: shape = [num_tokens, num_heads * head_size]
key: shape = [num_tokens, num_kv_heads * head_size]
value: shape = [num_tokens, num_kv_heads * head_size]
kv_cache = [2, num_blocks, block_size * num_kv_heads * head_size]
NOTE: kv_cache will be an empty tensor with shape [0]
for profiling run.
attn_metadata: Metadata for attention.
Returns:
shape = [num_tokens, num_heads * head_size]
"""
if output_scale is not None:
raise NotImplementedError(
"fused output quantization is not yet supported"
" for IpexAttentionImpl")
assert layer._k_scale_float == 1.0 and layer._v_scale_float == 1.0
num_tokens, hidden_size = query.shape
# Reshape the query, key, and value tensors.
query = query.view(-1, self.num_heads, self.head_size)
key = key.view(-1, self.num_kv_heads, self.head_size)
value = value.view(-1, self.num_kv_heads, self.head_size)
if kv_cache.numel() > 0:
key_cache, value_cache = self.split_kv_cache(
kv_cache, self.num_kv_heads, self.head_size)
ipex_ops.reshape_and_cache(
key,
value,
key_cache,
value_cache,
attn_metadata.slot_mapping.flatten(),
self.kv_cache_dtype,
layer._k_scale_float,
layer._v_scale_float,
)
if attn_metadata.is_prompt:
assert attn_metadata.seq_lens is not None
if (kv_cache.numel() == 0
or attn_metadata.block_tables.numel() == 0):
if self.num_kv_heads != self.num_heads:
key = key.repeat_interleave(self.num_queries_per_kv, dim=1)
value = value.repeat_interleave(self.num_queries_per_kv,
dim=1)
if attn_metadata.attn_bias is None:
if self.sliding_window is not None:
att_masks = _make_sliding_window_bias(
attn_metadata.seq_lens, self.sliding_window,
query.dtype) # type: ignore
else:
att_masks = _make_sliding_window_bias(
attn_metadata.seq_lens, None, dtype=query.dtype)
attn_metadata.attn_bias = att_masks
output = torch.empty(
(num_tokens, self.num_heads, self.head_size),
dtype=query.dtype,
device=query.device)
ipex_ops.varlen_attention(
query,
key,
value,
output,
attn_metadata.seqlen_q,
attn_metadata.seqlen_q,
self.alibi_slopes,
attn_metadata.max_seqlen,
attn_metadata.max_seqlen,
pdropout=0.0,
softmax_scale=self.scale,
zero_tensors=False,
is_causal=True,
return_softmax=False,
gen_=None,
window_size_left=-1,
window_size_right=-1,
logits_soft_cap=self.logits_soft_cap,
)
else:
# prefix-enabled attention
raise RuntimeError(
"IPEX backend doesn't support prefix decoding.")
else:
# Decoding run.
max_seq_len = attn_metadata.max_decode_seq_len
output = torch.empty_like(query)
block_size = value_cache.shape[3]
num_seqs, num_heads, head_size = query.shape
max_num_partitions = ((max_seq_len + _PARTITION_SIZE - 1) //
_PARTITION_SIZE)
# NOTE(woosuk): We use a simple heuristic to decide whether to use
# PagedAttention V1 or V2. If the number of partitions is 1, we use
# V1 to avoid the overhead of reduction. Also, if the number of
# sequences or heads is large, we use V1 since there is enough work
# to parallelize.
# TODO(woosuk): Tune this heuristic.
# For context len > 8192, use V2 kernel to avoid shared memory
# shortage.
use_v1 = (max_seq_len <= 8192 and
(max_num_partitions == 1 or num_seqs * num_heads > 512))
if use_v1:
# Run PagedAttention V1.
ipex_ops.paged_attention_v1(
output,
query,
key_cache,
value_cache,
self.num_kv_heads,
self.scale,
attn_metadata.block_tables,
attn_metadata.seq_lens_tensor,
block_size,
max_seq_len,
self.alibi_slopes,
self.kv_cache_dtype,
layer._k_scale_float,
layer._v_scale_float,
)
else:
# Run PagedAttention V2.
assert _PARTITION_SIZE % block_size == 0
tmp_output = torch.empty(
size=(num_seqs, num_heads, max_num_partitions, head_size),
dtype=output.dtype,
device=output.device,
)
exp_sums = torch.empty(
size=(num_seqs, num_heads, max_num_partitions),
dtype=torch.float32,
device=output.device,
)
max_logits = torch.empty_like(exp_sums)
ipex_ops.paged_attention_v2(
output,
exp_sums,
max_logits,
tmp_output,
query,
key_cache,
value_cache,
self.num_kv_heads,
self.scale,
attn_metadata.block_tables,
attn_metadata.seq_lens_tensor,
block_size,
max_seq_len,
self.alibi_slopes,
self.kv_cache_dtype,
layer._k_scale_float,
layer._v_scale_float,
)
# Reshape the output tensor.
return output.view(-1, self.num_heads * self.head_size)
def _make_alibi_bias(
alibi_slopes: torch.Tensor,
dtype: torch.dtype,
seq_lens: List[int],
) -> List[torch.Tensor]:
attn_biases = []
for seq_len in seq_lens:
bias = torch.arange(seq_len, dtype=dtype, device=alibi_slopes.device)
# NOTE(zhuohan): HF uses
# `bias = bias[None, :].repeat(seq_len, 1)`
# here. We find that both biases give the same results, but
# the bias below more accurately follows the original ALiBi
# paper.
bias = bias[None, :] - bias[:, None]
num_heads = alibi_slopes.shape[0]
bias = bias[None, :].repeat((num_heads, 1, 1))
bias.mul_(alibi_slopes[:, None, None])
inf_mask = torch.empty(
(1, seq_len, seq_len),
dtype=bias.dtype,
device=alibi_slopes.device).fill_(-torch.inf).triu_(diagonal=1)
attn_biases.append((bias + inf_mask).to(dtype))
return attn_biases
def _make_sliding_window_bias(
seq_lens: List[int],
window_size: Optional[int],
dtype: torch.dtype,
) -> List[torch.Tensor]:
attn_biases = []
for seq_len in seq_lens:
tensor = torch.full(
(1, seq_len, seq_len),
dtype=dtype,
fill_value=1,
)
shift = 0
mask = torch.tril(tensor, diagonal=shift).to(dtype) # type: ignore
if window_size is not None:
mask = torch.triu(mask, diagonal=shift - window_size + 1)
mask = torch.log(mask)
attn_biases.append(mask.to(dtype))
return attn_biases
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# 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 torch_xla.experimental.custom_kernel # Required to register custom ops.
from vllm.attention.backends.abstract import (AttentionBackend, AttentionImpl,
AttentionLayer,
AttentionMetadata, AttentionType,
is_quantized_kv_cache)
from vllm.attention.backends.utils import CommonAttentionState
from vllm.logger import init_logger
logger = init_logger(__name__)
class PallasAttentionBackend(AttentionBackend):
@staticmethod
def get_name() -> str:
return "PALLAS"
@staticmethod
def get_impl_cls() -> Type["PallasAttentionBackendImpl"]:
return PallasAttentionBackendImpl
@staticmethod
def get_metadata_cls() -> Type["PallasMetadata"]:
return PallasMetadata
@staticmethod
def get_state_cls() -> Type["CommonAttentionState"]:
return CommonAttentionState
@staticmethod
def get_kv_cache_shape(
num_blocks: int,
block_size: int,
num_kv_heads: int,
head_size: int,
) -> Tuple[int, ...]:
return (num_kv_heads, 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:
raise RuntimeError("swap_blocks is not used for the TPU backend.")
@torch.compile(backend="openxla")
@staticmethod
def copy_blocks(
kv_caches: List[Tuple[torch.Tensor, torch.Tensor]],
src_to_dists: Tuple[torch.Tensor, torch.Tensor],
) -> None:
src_indices, dst_indices = src_to_dists
for k_cache, v_cache in kv_caches:
torch.ops.xla.dynamo_set_buffer_donor_(k_cache, True)
k_cache[:, dst_indices] = k_cache[:, src_indices]
torch.ops.xla.dynamo_set_buffer_donor_(v_cache, True)
v_cache[:, dst_indices] = v_cache[:, src_indices]
@dataclass
class PallasMetadata(AttentionMetadata):
# Currently, input sequences can only contain all prefills
# or all decoding.
block_tables: Optional[torch.Tensor] = None
context_lens: Optional[torch.Tensor] = None
effective_query_lens: Optional[torch.Tensor] = None
@property
def prefill_metadata(self) -> Optional["PallasMetadata"]:
if self.num_prefills == 0:
return None
assert self.num_decode_tokens == 0
return self
@property
def decode_metadata(self) -> Optional["PallasMetadata"]:
if self.num_decode_tokens == 0:
return None
assert self.num_prefills == 0
assert self.num_prefill_tokens == 0
assert self.block_tables is not None
assert self.context_lens is not None
return self
class PallasAttentionBackendImpl(AttentionImpl):
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]] = None,
logits_soft_cap: Optional[float] = None,
attn_type: str = AttentionType.DECODER,
kv_sharing_target_layer_name: Optional[str] = None,
use_irope: bool = False,
) -> None:
if kv_sharing_target_layer_name is not None:
raise NotImplementedError("KV sharing is not supported in V0.")
if use_irope:
logger.warning_once(
"Using irope in Pallas is not supported yet, it will fall back "
"to global attention for long context.")
self.num_heads = num_heads
self.head_size = head_size
self.scale = float(scale)
self.num_kv_heads = num_kv_heads
self.num_queries_per_kv = self.num_heads // self.num_kv_heads
self.logits_soft_cap = logits_soft_cap
if head_size % 128 != 0:
raise NotImplementedError(
f"Head size must be a multiple of 128, found {head_size}.")
if alibi_slopes is not None:
raise NotImplementedError("Alibi slopes is not supported.")
if sliding_window is not None:
raise NotImplementedError("Sliding window is not supported.")
if is_quantized_kv_cache(kv_cache_dtype):
raise NotImplementedError("FP8 KV cache dtype is not supported.")
if blocksparse_params is not None:
raise NotImplementedError("Blocksparse is not supported.")
if torch_xla.tpu.version() < 4:
raise NotImplementedError("TPU version must be 4 or higher.")
self.megacore_mode = None
tpu_env = torch_xla.tpu.get_tpu_env()
tpu_type = (tpu_env.get("ACCELERATOR_TYPE", None)
or tpu_env.get("TYPE", None)
or tpu_env.get("TPU_ACCELERATOR_TYPE", None))
assert tpu_type is not None
tpu_type = tpu_type.lower()
if (("lite" not in tpu_type) and ("v6" not in tpu_type)):
if self.num_kv_heads % 2 == 0:
self.megacore_mode = "kv_head"
else:
# NOTE(woosuk): If the batch size is not a multiple of 2, the
# megacore mode will be None.
self.megacore_mode = "batch"
if attn_type != AttentionType.DECODER:
raise NotImplementedError("Encoder self-attention and "
"encoder/decoder cross-attention "
"are not implemented for "
"PallasAttentionBackendImpl")
def forward(
self,
layer: AttentionLayer,
query: torch.Tensor,
key: torch.Tensor,
value: torch.Tensor,
kv_cache: Tuple[torch.Tensor, torch.Tensor],
attn_metadata: PallasMetadata,
output: Optional[torch.Tensor] = None,
output_scale: Optional[torch.Tensor] = None,
) -> torch.Tensor:
"""Forward pass with Pallas attention.
Args:
query: shape = [batch_size, seq_len, num_heads * head_size]
key: shape = [batch_size, seq_len, num_kv_heads * head_size]
value: shape = [batch_size, seq_len, num_kv_heads * head_size]
kv_cache[0] = [num_kv_heads, num_blocks, block_size, head_size]
kv_cache[1] = [num_kv_heads, num_blocks, block_size, head_size]
NOTE: kv_cache[0] and kv_cache[1] will be an empty tensor
with shape [0] for profiling run.
attn_metadata: Metadata for attention.
Returns:
shape = [batch_size, seq_len, num_heads * head_size]
"""
if output_scale is not None:
raise NotImplementedError(
"fused output quantization is not yet supported"
" for PallasAttentionImpl")
assert layer._k_scale_float == 1.0 and layer._v_scale_float == 1.0
batch_size, seq_len, hidden_size = query.shape
query = query.view(batch_size, seq_len, self.num_heads, self.head_size)
key = key.view(batch_size, seq_len, self.num_kv_heads, self.head_size)
value = value.view(batch_size, seq_len, self.num_kv_heads,
self.head_size)
if kv_cache[0].numel() > 0:
slot_mapping = attn_metadata.slot_mapping
key_cache, value_cache = kv_cache
write_to_kv_cache(key, value, key_cache, value_cache, slot_mapping)
query = query * self.scale
if attn_metadata.num_prefills > 0:
if attn_metadata.block_tables is None:
# Prefill without paged KV cache.
assert seq_len % 16 == 0, (
"Pallas FlashAttention kernel requires seq_len to be a "
f"multiple of 16 but got {seq_len}")
# Handle GQA/MQA.
if self.num_kv_heads != self.num_heads:
key = key.repeat_interleave(self.num_queries_per_kv,
dim=-2)
key = key.view(batch_size, seq_len, self.num_heads,
self.head_size)
value = value.repeat_interleave(self.num_queries_per_kv,
dim=-2)
value = value.view(batch_size, seq_len, self.num_heads,
self.head_size)
# FlashAttention kernel requires the input shape to be
# [batch_size, num_heads, seq_len, d_model]
# while the input is [batch_size, seq_len, num_heads, d_model].
# Permute the input to match the required format.
output = torch.ops.xla.flash_attention(
query.permute(0, 2, 1, 3),
key.permute(0, 2, 1, 3),
value.permute(0, 2, 1, 3),
True,
)
output = output.permute(0, 2, 1, 3)
else:
# Prefill with paged KV cache.
# TODO(woosuk): Tune the below knobs.
num_kv_pages_per_compute_block = 16
num_queries_per_compute_block = 16
assert seq_len % num_queries_per_compute_block == 0
output = torch.ops.xla.multi_queries_paged_attention(
query,
key_cache,
value_cache,
attn_metadata.context_lens,
attn_metadata.block_tables,
attn_metadata.effective_query_lens,
num_kv_pages_per_compute_block,
num_queries_per_compute_block,
use_kernel=True,
attn_logits_soft_cap=self.logits_soft_cap,
)
else:
# Decoding run.
assert kv_cache[0].numel() > 0
query = query.squeeze(dim=1)
pages_per_compute_block = 16 # TODO(woosuk): Tune this value.
assert attn_metadata.block_tables is not None
assert attn_metadata.context_lens is not None
# NOTE(woosuk): The PagedAttention Pallas kernel stores the entire
# block table in SMEM. Therefore, if the block table is too large,
# the kernel compilation will fail. To avoid this, we split the
# batch dimension into smaller chunks and run the kernel multiple
# times.
MAX_SMEM_USAGE = 512 * 1024
size_per_seq = 4 * attn_metadata.block_tables.shape[1]
max_num_seq = MAX_SMEM_USAGE // size_per_seq
if batch_size <= max_num_seq:
output = paged_attention(
query,
key_cache,
value_cache,
attn_metadata.context_lens,
attn_metadata.block_tables,
pages_per_compute_block,
self.megacore_mode,
attn_logits_soft_cap=self.logits_soft_cap,
)
else:
chunk_size = max_num_seq
# Make sure the chunk size is a multiple of 2.
chunk_size = chunk_size // 2 * 2
num_chunks = (batch_size + chunk_size - 1) // chunk_size
output = torch.empty_like(query)
for chunk_idx in range(num_chunks):
chunk_start = chunk_idx * chunk_size
chunk_end = chunk_start + chunk_size
# NOTE(woosuk): We skip this line because it causes Dynamo
# compilation error. Instead, we rely on the slice operation
# to handle the out-of-bound case.
# chunk_end = min(chunk_end, batch_size)
chunk_output = paged_attention(
query[chunk_start:chunk_end],
key_cache,
value_cache,
attn_metadata.context_lens[chunk_start:chunk_end],
attn_metadata.block_tables[chunk_start:chunk_end],
pages_per_compute_block,
self.megacore_mode,
attn_logits_soft_cap=self.logits_soft_cap,
)
output[chunk_start:chunk_end] = chunk_output
# Reshape the output tensor.
return output.reshape(batch_size, seq_len, hidden_size)
def write_to_kv_cache(
key: torch.Tensor,
value: torch.Tensor,
key_cache: torch.Tensor,
value_cache: torch.Tensor,
slot_mapping: torch.Tensor,
) -> None:
torch.ops.xla.dynamo_set_buffer_donor_(key_cache, True)
torch.ops.xla.dynamo_set_buffer_donor_(value_cache, True)
key = key.flatten(0, 2)
value = value.flatten(0, 2)
key_cache = key_cache.flatten(0, 2)
value_cache = value_cache.flatten(0, 2)
key_cache.index_copy_(0, slot_mapping, key)
value_cache.index_copy_(0, slot_mapping, value)
def paged_attention(
query: torch.Tensor,
key_cache: torch.Tensor,
value_cache: torch.Tensor,
context_lens: torch.Tensor,
block_tables: torch.Tensor,
pages_per_compute_block: int,
megacore_mode: Optional[str],
*,
attn_logits_soft_cap: Optional[float],
) -> torch.Tensor:
batch_size = query.shape[0]
if megacore_mode == "batch" and batch_size % 2 != 0:
megacore_mode = None
else:
megacore_mode = megacore_mode
return torch.ops.xla.paged_attention(
query,
key_cache,
value_cache,
context_lens,
block_tables,
pages_per_compute_block,
megacore_mode=megacore_mode,
attn_logits_soft_cap=attn_logits_soft_cap,
)
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