vllm/tests/kernels/attention/test_cpu_attn.py
Li, Jiang 7f829be7d3
[CPU] Refactor CPU attention backend (#27954)
Signed-off-by: jiang1.li <jiang1.li@intel.com>
2025-11-12 09:43:06 +08:00

576 lines
17 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import functools
import math
import pytest
import torch
from vllm.platforms import current_platform
if not current_platform.is_cpu():
pytest.skip("skipping CPU-only tests", allow_module_level=True)
from vllm._custom_ops import (
cpu_attention_with_kv_cache,
cpu_attn_get_scheduler_metadata,
cpu_attn_reshape_and_cache,
)
NUM_HEADS = [
(4, 4),
(8, 2),
(9, 3),
]
HEAD_SIZES = [96, 128]
QTYPES = [torch.bfloat16, torch.half, torch.float32]
SLIDING_WINDOWS = [None, 256]
NUM_BLOCKS = [
1024,
]
SEQ_LENS = [ # (q_len, kv_len)
[(1, 213), (1, 1), (1, 312), (1, 7), (1, 7812)], # decode batch
[(2345, 2345), (5, 5), (3, 16), (134, 5131)], # prefill batch
[(992, 2456), (1, 1234), (98, 1145), (1, 4162), (2345, 2345)], # mixed batch
]
# rand number generation takes too much time, cache rand tensors
@functools.lru_cache(maxsize=128, typed=False)
def tensor_cache(
elem_num: int,
dtype: torch.dtype,
) -> torch.Tensor:
tensor = torch.randn(elem_num, dtype=dtype)
return tensor
def _get_alibi_slopes(total_num_heads: int) -> torch.Tensor:
closest_power_of_2 = 2 ** math.floor(math.log2(total_num_heads))
base = torch.tensor(
2 ** (-(2 ** -(math.log2(closest_power_of_2) - 3))),
dtype=torch.float32,
)
powers = torch.arange(1, 1 + closest_power_of_2, dtype=torch.int32)
slopes = torch.pow(base, powers)
if closest_power_of_2 != total_num_heads:
extra_base = torch.tensor(
2 ** (-(2 ** -(math.log2(2 * closest_power_of_2) - 3))),
dtype=torch.float32,
)
num_remaining_heads = min(
closest_power_of_2, total_num_heads - closest_power_of_2
)
extra_powers = torch.arange(
start=1, end=1 + 2 * num_remaining_heads, step=2, dtype=torch.int32
)
slopes = torch.cat([slopes, torch.pow(extra_base, extra_powers)], dim=0)
return slopes.float()
def ref_paged_attn(
query: torch.Tensor,
key_cache: torch.Tensor,
value_cache: torch.Tensor,
query_lens: list[int],
kv_lens: list[int],
block_tables: torch.Tensor,
scale: float,
sliding_window: int | None = None,
soft_cap: float | None = None,
alibi_slopes: torch.Tensor | None = None,
s_aux: torch.Tensor | None = None,
) -> torch.Tensor:
num_seqs = len(query_lens)
block_tables = block_tables.cpu().numpy()
_, block_size, num_kv_heads, head_size = key_cache.shape
dtype = query.dtype
outputs: list[torch.Tensor] = []
start_idx = 0
if alibi_slopes is not None:
alibi_slopes = alibi_slopes[:, None, None]
if s_aux is not None:
s_aux = s_aux.float()
s_aux = s_aux[:, None, None]
for i in range(num_seqs):
query_len = query_lens[i]
kv_len = kv_lens[i]
q = query[start_idx : start_idx + query_len].float()
q *= scale
num_kv_blocks = (kv_len + block_size - 1) // block_size
block_indices = block_tables[i, :num_kv_blocks]
k = key_cache[block_indices].view(-1, num_kv_heads, head_size)
k = k[:kv_len].float()
v = value_cache[block_indices].view(-1, num_kv_heads, head_size)
v = v[:kv_len].float()
if q.shape[1] != k.shape[1]:
k = torch.repeat_interleave(k, q.shape[1] // k.shape[1], dim=1)
v = torch.repeat_interleave(v, q.shape[1] // v.shape[1], dim=1)
attn = torch.einsum("qhd,khd->hqk", q, k).float()
empty_mask = torch.ones(query_len, kv_len)
mask = torch.triu(empty_mask, diagonal=kv_len - query_len + 1).bool()
if sliding_window is not None:
sliding_window_mask = (
torch.triu(
empty_mask, diagonal=kv_len - (query_len + sliding_window) + 1
)
.bool()
.logical_not()
)
mask |= sliding_window_mask
if soft_cap is not None:
attn = soft_cap * torch.tanh(attn / soft_cap)
if alibi_slopes is not None:
q_start_pos = kv_len - query_len
q_pos = q_start_pos + torch.arange(0, query_len)[None, :, None]
kv_pos = torch.arange(0, kv_len)[None, None, :]
dist = q_pos - kv_pos
alibi_bias = -alibi_slopes * dist
attn += alibi_bias
attn.masked_fill_(mask, float("-inf"))
if s_aux is not None:
s_aux_ext = s_aux.repeat(1, query_len, 1)
attn = torch.cat((s_aux_ext, attn), dim=-1)
attn = torch.softmax(attn, dim=-1)
if s_aux is not None:
attn = attn[:, :, 1:]
out = torch.einsum("hqk,khd->qhd", attn, v).to(dtype=dtype)
outputs.append(out)
start_idx += query_len
return torch.cat(outputs, dim=0)
@torch.inference_mode()
def varlen_with_paged_kv(
seq_lens: list[tuple[int, int]],
num_heads: tuple[int, int],
head_size: int,
sliding_window: int | None,
dtype: torch.dtype,
block_size: int,
soft_cap: float | None,
num_blocks: int,
use_alibi: bool,
use_sink: bool,
isa: str,
) -> None:
current_platform.seed_everything(0)
num_seqs = len(seq_lens)
query_lens = [x[0] for x in seq_lens]
kv_lens = [x[1] for x in seq_lens]
num_query_heads = num_heads[0]
num_kv_heads = num_heads[1]
assert num_query_heads % num_kv_heads == 0
max_kv_len = max(kv_lens)
window_size = (sliding_window - 1, 0) if sliding_window is not None else (-1, -1)
scale = head_size**-0.5
token_num = sum(query_lens)
# for n heads the set of slopes is the geometric sequence that starts
# 2^(-8/n)
alibi_slopes = _get_alibi_slopes(num_query_heads) if use_alibi else None
s_aux = (
15 * torch.rand((num_query_heads,), dtype=torch.bfloat16) if use_sink else None
)
query = tensor_cache(
elem_num=token_num * num_query_heads * head_size,
dtype=dtype,
)
query = query.view(
token_num,
num_query_heads,
head_size,
)
key_value = tensor_cache(
elem_num=2 * num_blocks * num_kv_heads * block_size * head_size,
dtype=dtype,
)
key_value = key_value.view(
2,
num_blocks,
block_size,
num_kv_heads,
head_size,
)
key_cache, value_cache = key_value.unbind(0)
# KV cache for CPU attention
packed_key_cache = torch.empty(
num_blocks, num_kv_heads, block_size, head_size, dtype=dtype
)
packed_value_cache = torch.empty_like(packed_key_cache)
cu_query_lens = torch.tensor([0] + query_lens, dtype=torch.int32).cumsum(
dim=0, dtype=torch.int32
)
kv_lens_tensor = torch.tensor(kv_lens, dtype=torch.int32)
max_num_blocks_per_seq = (max_kv_len + block_size - 1) // block_size
block_tables = torch.randint(
0, num_blocks, (num_seqs, max_num_blocks_per_seq), dtype=torch.int32
)
# use reshape_and_cache to pack key_cache and value_cache
slot_mapping = torch.arange(0, num_blocks * block_size, dtype=torch.int64)
cpu_attn_reshape_and_cache(
key=key_cache.view(-1, num_kv_heads, head_size),
value=value_cache.view(-1, num_kv_heads, head_size),
key_cache=packed_key_cache,
value_cache=packed_value_cache,
slot_mapping=slot_mapping,
isa=isa,
)
metadata = cpu_attn_get_scheduler_metadata(
num_reqs=num_seqs,
num_heads=num_query_heads,
num_kv_heads=num_kv_heads,
head_dim=head_size,
seq_lens=kv_lens_tensor,
dtype=dtype,
query_start_loc=cu_query_lens,
causal=True,
sliding_window_size=sliding_window if sliding_window is not None else -1,
isa=isa,
enable_kv_split=False,
)
out_without_split = torch.empty_like(query)
cpu_attention_with_kv_cache(
query=query,
key_cache=packed_key_cache,
value_cache=packed_value_cache,
output=out_without_split,
query_start_loc=cu_query_lens,
seq_lens=kv_lens_tensor,
scale=scale,
causal=True,
alibi_slopes=alibi_slopes,
sliding_window=window_size,
block_table=block_tables,
softcap=soft_cap if soft_cap is not None else 0,
scheduler_metadata=metadata,
s_aux=s_aux,
)
metadata = cpu_attn_get_scheduler_metadata(
num_reqs=num_seqs,
num_heads=num_query_heads,
num_kv_heads=num_kv_heads,
head_dim=head_size,
seq_lens=kv_lens_tensor,
dtype=dtype,
query_start_loc=cu_query_lens,
causal=True,
sliding_window_size=sliding_window if sliding_window is not None else -1,
isa=isa,
enable_kv_split=True,
)
out_with_split = torch.empty_like(query)
cpu_attention_with_kv_cache(
query=query,
key_cache=packed_key_cache,
value_cache=packed_value_cache,
output=out_with_split,
query_start_loc=cu_query_lens,
seq_lens=kv_lens_tensor,
scale=scale,
causal=True,
alibi_slopes=alibi_slopes,
sliding_window=window_size,
block_table=block_tables,
softcap=soft_cap if soft_cap is not None else 0,
scheduler_metadata=metadata,
s_aux=s_aux,
)
ref_output = ref_paged_attn(
query=query,
key_cache=key_cache,
value_cache=value_cache,
query_lens=query_lens,
kv_lens=kv_lens,
block_tables=block_tables,
scale=scale,
sliding_window=sliding_window,
soft_cap=soft_cap,
alibi_slopes=alibi_slopes,
s_aux=s_aux,
)
atol, rtol = 1.5e-2, 1e-2
(
torch.testing.assert_close(out_with_split, ref_output, atol=atol, rtol=rtol),
f"{torch.max(torch.abs(out_with_split - ref_output))}",
)
(
torch.testing.assert_close(out_without_split, ref_output, atol=atol, rtol=rtol),
f"{torch.max(torch.abs(out_without_split - ref_output))}",
)
@pytest.mark.parametrize("seq_lens", SEQ_LENS)
@pytest.mark.parametrize("num_heads", NUM_HEADS)
@pytest.mark.parametrize("head_size", HEAD_SIZES)
@pytest.mark.parametrize("block_size", [96, 128])
@pytest.mark.parametrize("sliding_window", SLIDING_WINDOWS)
@pytest.mark.parametrize("dtype", QTYPES)
@pytest.mark.parametrize("soft_cap", [None])
@pytest.mark.parametrize("num_blocks", NUM_BLOCKS)
@pytest.mark.parametrize("use_alibi", [False])
@pytest.mark.parametrize("use_sink", [False])
@pytest.mark.parametrize("isa", ["vec"])
def test_varlen_with_paged_kv_normal_vec(
seq_lens: list[tuple[int, int]],
num_heads: tuple[int, int],
head_size: int,
sliding_window: int | None,
dtype: torch.dtype,
block_size: int,
soft_cap: float | None,
num_blocks: int,
use_alibi: bool,
use_sink: bool,
isa: str,
) -> None:
varlen_with_paged_kv(
seq_lens=seq_lens,
num_heads=num_heads,
head_size=head_size,
sliding_window=sliding_window,
dtype=dtype,
block_size=block_size,
soft_cap=soft_cap,
num_blocks=num_blocks,
use_alibi=use_alibi,
use_sink=use_sink,
isa=isa,
)
@pytest.mark.parametrize("seq_lens", SEQ_LENS)
@pytest.mark.parametrize("num_heads", NUM_HEADS)
@pytest.mark.parametrize("head_size", HEAD_SIZES)
@pytest.mark.parametrize("block_size", [96, 128])
@pytest.mark.parametrize("sliding_window", SLIDING_WINDOWS)
@pytest.mark.parametrize("dtype", [torch.bfloat16])
@pytest.mark.parametrize("soft_cap", [None])
@pytest.mark.parametrize("num_blocks", NUM_BLOCKS)
@pytest.mark.parametrize("use_alibi", [False])
@pytest.mark.parametrize("use_sink", [False])
@pytest.mark.parametrize("isa", ["amx"])
@pytest.mark.skipif(
not torch._C._cpu._is_amx_tile_supported(), reason="no AMX support."
)
def test_varlen_with_paged_kv_normal_amx(
seq_lens: list[tuple[int, int]],
num_heads: tuple[int, int],
head_size: int,
sliding_window: int | None,
dtype: torch.dtype,
block_size: int,
soft_cap: float | None,
num_blocks: int,
use_alibi: bool,
use_sink: bool,
isa: str,
) -> None:
varlen_with_paged_kv(
seq_lens=seq_lens,
num_heads=num_heads,
head_size=head_size,
sliding_window=sliding_window,
dtype=dtype,
block_size=block_size,
soft_cap=soft_cap,
num_blocks=num_blocks,
use_alibi=use_alibi,
use_sink=use_sink,
isa=isa,
)
@pytest.mark.parametrize("seq_lens", SEQ_LENS)
@pytest.mark.parametrize("num_heads", NUM_HEADS)
@pytest.mark.parametrize("head_size", HEAD_SIZES)
@pytest.mark.parametrize("block_size", [48])
@pytest.mark.parametrize("sliding_window", SLIDING_WINDOWS)
@pytest.mark.parametrize("dtype", [torch.bfloat16])
@pytest.mark.parametrize("soft_cap", [None])
@pytest.mark.parametrize("num_blocks", NUM_BLOCKS)
@pytest.mark.parametrize("use_alibi", [False])
@pytest.mark.parametrize("use_sink", [False])
@pytest.mark.parametrize("isa", ["vec16"])
def test_varlen_with_paged_kv_normal_vec16(
seq_lens: list[tuple[int, int]],
num_heads: tuple[int, int],
head_size: int,
sliding_window: int | None,
dtype: torch.dtype,
block_size: int,
soft_cap: float | None,
num_blocks: int,
use_alibi: bool,
use_sink: bool,
isa: str,
) -> None:
varlen_with_paged_kv(
seq_lens=seq_lens,
num_heads=num_heads,
head_size=head_size,
sliding_window=sliding_window,
dtype=dtype,
block_size=block_size,
soft_cap=soft_cap,
num_blocks=num_blocks,
use_alibi=use_alibi,
use_sink=use_sink,
isa=isa,
)
@pytest.mark.parametrize("seq_lens", SEQ_LENS)
@pytest.mark.parametrize("num_heads", NUM_HEADS)
@pytest.mark.parametrize("head_size", [96])
@pytest.mark.parametrize("block_size", [128])
@pytest.mark.parametrize("sliding_window", SLIDING_WINDOWS)
@pytest.mark.parametrize("dtype", [torch.bfloat16])
@pytest.mark.parametrize("soft_cap", [50])
@pytest.mark.parametrize("num_blocks", NUM_BLOCKS)
@pytest.mark.parametrize("use_alibi", [False])
@pytest.mark.parametrize("use_sink", [False])
@pytest.mark.parametrize(
"isa", ["amx"] if torch._C._cpu._is_amx_tile_supported() else ["vec"]
)
def test_varlen_with_paged_kv_softcap(
seq_lens: list[tuple[int, int]],
num_heads: tuple[int, int],
head_size: int,
sliding_window: int | None,
dtype: torch.dtype,
block_size: int,
soft_cap: float | None,
num_blocks: int,
use_alibi: bool,
use_sink: bool,
isa: str,
) -> None:
varlen_with_paged_kv(
seq_lens=seq_lens,
num_heads=num_heads,
head_size=head_size,
sliding_window=sliding_window,
dtype=dtype,
block_size=block_size,
soft_cap=soft_cap,
num_blocks=num_blocks,
use_alibi=use_alibi,
use_sink=use_sink,
isa=isa,
)
@pytest.mark.parametrize("seq_lens", SEQ_LENS)
@pytest.mark.parametrize("num_heads", NUM_HEADS)
@pytest.mark.parametrize("head_size", [96])
@pytest.mark.parametrize("block_size", [128])
@pytest.mark.parametrize("sliding_window", SLIDING_WINDOWS)
@pytest.mark.parametrize("dtype", [torch.bfloat16])
@pytest.mark.parametrize("soft_cap", [None])
@pytest.mark.parametrize("num_blocks", NUM_BLOCKS)
@pytest.mark.parametrize("use_alibi", [True])
@pytest.mark.parametrize("use_sink", [False])
@pytest.mark.parametrize(
"isa", ["amx"] if torch._C._cpu._is_amx_tile_supported() else ["vec"]
)
def test_varlen_with_paged_kv_alibi(
seq_lens: list[tuple[int, int]],
num_heads: tuple[int, int],
head_size: int,
sliding_window: int | None,
dtype: torch.dtype,
block_size: int,
soft_cap: float | None,
num_blocks: int,
use_alibi: bool,
use_sink: bool,
isa: str,
) -> None:
varlen_with_paged_kv(
seq_lens=seq_lens,
num_heads=num_heads,
head_size=head_size,
sliding_window=sliding_window,
dtype=dtype,
block_size=block_size,
soft_cap=soft_cap,
num_blocks=num_blocks,
use_alibi=use_alibi,
use_sink=use_sink,
isa=isa,
)
@pytest.mark.parametrize("seq_lens", SEQ_LENS)
@pytest.mark.parametrize("num_heads", NUM_HEADS)
@pytest.mark.parametrize("head_size", [96])
@pytest.mark.parametrize("block_size", [128])
@pytest.mark.parametrize("sliding_window", SLIDING_WINDOWS)
@pytest.mark.parametrize("dtype", [torch.bfloat16])
@pytest.mark.parametrize("soft_cap", [None])
@pytest.mark.parametrize("num_blocks", NUM_BLOCKS)
@pytest.mark.parametrize("use_alibi", [False])
@pytest.mark.parametrize("use_sink", [True])
@pytest.mark.parametrize(
"isa", ["amx"] if torch._C._cpu._is_amx_tile_supported() else ["vec"]
)
def test_varlen_with_paged_kv_sink(
seq_lens: list[tuple[int, int]],
num_heads: tuple[int, int],
head_size: int,
sliding_window: int | None,
dtype: torch.dtype,
block_size: int,
soft_cap: float | None,
num_blocks: int,
use_alibi: bool,
use_sink: bool,
isa: str,
) -> None:
varlen_with_paged_kv(
seq_lens=seq_lens,
num_heads=num_heads,
head_size=head_size,
sliding_window=sliding_window,
dtype=dtype,
block_size=block_size,
soft_cap=soft_cap,
num_blocks=num_blocks,
use_alibi=use_alibi,
use_sink=use_sink,
isa=isa,
)