vllm/tests/kernels/test_flash_attn.py
Russell Bryant e489ad7a21
[Misc] Add SPDX-License-Identifier headers to python source files (#12628)
- **Add SPDX license headers to python source files**
- **Check for SPDX headers using pre-commit**

commit 9d7ef44c3cfb72ca4c32e1c677d99259d10d4745
Author: Russell Bryant <rbryant@redhat.com>
Date:   Fri Jan 31 14:18:24 2025 -0500

    Add SPDX license headers to python source files
    
This commit adds SPDX license headers to python source files as
recommended to
the project by the Linux Foundation. These headers provide a concise way
that is
both human and machine readable for communicating license information
for each
source file. It helps avoid any ambiguity about the license of the code
and can
    also be easily used by tools to help manage license compliance.
    
The Linux Foundation runs license scans against the codebase to help
ensure
    we are in compliance with the licenses of the code we use, including
dependencies. Having these headers in place helps that tool do its job.
    
    More information can be found on the SPDX site:
    
    - https://spdx.dev/learn/handling-license-info/
    
    Signed-off-by: Russell Bryant <rbryant@redhat.com>

commit 5a1cf1cb3b80759131c73f6a9dddebccac039dea
Author: Russell Bryant <rbryant@redhat.com>
Date:   Fri Jan 31 14:36:32 2025 -0500

    Check for SPDX headers using pre-commit
    
    Signed-off-by: Russell Bryant <rbryant@redhat.com>

---------

Signed-off-by: Russell Bryant <rbryant@redhat.com>
2025-02-02 11:58:18 -08:00

257 lines
9.3 KiB
Python

# SPDX-License-Identifier: Apache-2.0
from typing import List, Optional, Tuple
import pytest
import torch
from vllm.platforms import current_platform
from vllm.vllm_flash_attn import (fa_version_unsupported_reason,
flash_attn_varlen_func,
flash_attn_with_kvcache,
is_fa_version_supported)
NUM_HEADS = [(4, 4), (8, 2), (16, 2)]
HEAD_SIZES = [128, 256]
BLOCK_SIZES = [16, 32]
DTYPES = [torch.float16, torch.bfloat16]
# one value large enough to test overflow in index calculation.
# one value small enough to test the schema op check
NUM_BLOCKS = [32768, 2048]
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: Optional[int] = None,
soft_cap: Optional[float] = None,
) -> torch.Tensor:
num_seqs = len(query_lens)
block_tables = block_tables.cpu().numpy()
_, block_size, num_kv_heads, head_size = key_cache.shape
outputs: List[torch.Tensor] = []
start_idx = 0
for i in range(num_seqs):
query_len = query_lens[i]
kv_len = kv_lens[i]
q = query[start_idx:start_idx + query_len]
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]
v = value_cache[block_indices].view(-1, num_kv_heads, head_size)
v = v[:kv_len]
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)
attn.masked_fill_(mask, float("-inf"))
attn = torch.softmax(attn, dim=-1).to(v.dtype)
out = torch.einsum("hqk,khd->qhd", attn, v)
outputs.append(out)
start_idx += query_len
return torch.cat(outputs, dim=0)
@pytest.mark.parametrize("use_out", [True, False])
@pytest.mark.parametrize("kv_lens", [[1328, 18, 463], [1, 54, 293, 70]])
@pytest.mark.parametrize("num_heads", NUM_HEADS)
@pytest.mark.parametrize("head_size", HEAD_SIZES)
@pytest.mark.parametrize("block_size", BLOCK_SIZES)
@pytest.mark.parametrize("dtype", DTYPES)
@pytest.mark.parametrize("soft_cap", [None, 10.0, 50.0])
@pytest.mark.parametrize("num_blocks", NUM_BLOCKS)
@pytest.mark.parametrize("sliding_window", [None, 256])
@pytest.mark.parametrize("fa_version", [2, 3])
@torch.inference_mode()
def test_flash_attn_with_paged_kv(
use_out: bool,
kv_lens: List[int],
num_heads: Tuple[int, int],
head_size: int,
dtype: torch.dtype,
block_size: int,
soft_cap: Optional[float],
num_blocks: int,
sliding_window: Optional[int],
fa_version: int,
) -> None:
torch.set_default_device("cuda")
if not is_fa_version_supported(fa_version):
pytest.skip(f"Flash attention version {fa_version} not supported due "
f"to: \"{fa_version_unsupported_reason(fa_version)}\"")
current_platform.seed_everything(0)
num_seqs = len(kv_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)
scale = head_size**-0.5
window_size = ((sliding_window - 1, 0) if sliding_window is not None else
(-1, -1))
query = torch.randn(num_seqs, num_query_heads, head_size, dtype=dtype)
key_cache = torch.randn(num_blocks,
block_size,
num_kv_heads,
head_size,
dtype=dtype)
value_cache = torch.randn_like(key_cache)
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)
q = query.unsqueeze(1)
out = torch.empty_like(q) if use_out else None
output = flash_attn_with_kvcache(
q=q,
k_cache=key_cache,
v_cache=value_cache,
out=out,
softmax_scale=scale,
causal=True,
block_table=block_tables,
cache_seqlens=kv_lens_tensor,
softcap=soft_cap if soft_cap is not None else 0,
window_size=window_size,
fa_version=fa_version,
)
output = output if not use_out else out
output = output.squeeze(1)
ref_output = ref_paged_attn(query=query,
key_cache=key_cache,
value_cache=value_cache,
query_lens=[1] * num_seqs,
kv_lens=kv_lens,
block_tables=block_tables,
scale=scale,
soft_cap=soft_cap,
sliding_window=sliding_window)
torch.testing.assert_close(output, ref_output, atol=2e-2, rtol=1e-2), \
f"{torch.max(torch.abs(output - ref_output))}"
@pytest.mark.parametrize("use_out", [True, False])
@pytest.mark.parametrize("seq_lens",
[[(1, 1328), (5, 18),
(129, 463)], [(1, 523), (1, 37), (1, 2011)]])
@pytest.mark.parametrize("num_heads", NUM_HEADS)
@pytest.mark.parametrize("head_size", HEAD_SIZES)
@pytest.mark.parametrize("block_size", BLOCK_SIZES)
@pytest.mark.parametrize("sliding_window", [None, 256])
@pytest.mark.parametrize("dtype", DTYPES)
@pytest.mark.parametrize("soft_cap", [None, 10.0, 50.0])
@pytest.mark.parametrize("num_blocks", NUM_BLOCKS)
@pytest.mark.parametrize("fa_version", [2, 3])
@torch.inference_mode()
def test_varlen_with_paged_kv(
use_out: bool,
seq_lens: List[Tuple[int, int]],
num_heads: Tuple[int, int],
head_size: int,
sliding_window: Optional[int],
dtype: torch.dtype,
block_size: int,
soft_cap: Optional[float],
num_blocks: int,
fa_version: int,
) -> None:
torch.set_default_device("cuda")
if not is_fa_version_supported(fa_version):
pytest.skip(f"Flash attention version {fa_version} not supported due "
f"to: \"{fa_version_unsupported_reason(fa_version)}\"")
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_query_len = max(query_lens)
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
query = torch.randn(sum(query_lens),
num_query_heads,
head_size,
dtype=dtype)
key_cache = torch.randn(num_blocks,
block_size,
num_kv_heads,
head_size,
dtype=dtype)
value_cache = torch.randn_like(key_cache)
cu_query_lens = torch.tensor([0] + query_lens,
dtype=torch.int32).cumsum(dim=0,
dtype=torch.int32)
kv_lens = 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)
out = torch.empty_like(query) if use_out else None
output = flash_attn_varlen_func(
q=query,
k=key_cache,
v=value_cache,
out=out,
cu_seqlens_q=cu_query_lens,
seqused_k=kv_lens,
max_seqlen_q=max_query_len,
max_seqlen_k=max_kv_len,
softmax_scale=scale,
causal=True,
window_size=window_size,
block_table=block_tables,
softcap=soft_cap if soft_cap is not None else 0,
fa_version=fa_version,
)
output = output if not use_out else out
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,
)
torch.testing.assert_close(output, ref_output, atol=2e-2, rtol=1e-2), \
f"{torch.max(torch.abs(output - ref_output))}"