vllm/tests/kernels/attention/test_attention_selector.py

261 lines
11 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from unittest.mock import patch
import pytest
import torch
from vllm.attention.selector import _cached_get_attn_backend, get_attn_backend
from vllm.platforms.cpu import CpuPlatform
from vllm.platforms.cuda import CudaPlatform
from vllm.platforms.rocm import RocmPlatform
from vllm.utils import STR_BACKEND_ENV_VAR, STR_FLASH_ATTN_VAL, STR_INVALID_VAL
@pytest.fixture(autouse=True)
def clear_cache():
"""Clear lru cache to ensure each test case runs without caching.
"""
_cached_get_attn_backend.cache_clear()
# Define MLA and non-MLA backends separately
DEVICE_MLA_BACKENDS = {
"cuda": ["TRITON_MLA", "FLASHMLA"],
"hip": ["TRITON_MLA", "ROCM_AITER_MLA"],
"cpu": [],
}
DEVICE_REGULAR_ATTN_BACKENDS = {
"cuda": ["XFORMERS", "FLASHINFER"],
"hip": ["ROCM_FLASH"],
"cpu": ["TORCH_SDPA"],
}
DEVICE_MLA_BLOCK_SIZES = {
"cuda": [16, 64], # CUDA supports both standard and extended block sizes
"hip": [16, 1], # HIP requires special handling for block_size=1
"cpu": [16] # CPU uses fixed block size from test cases
}
def generate_params():
params = []
for use_mla in [True, False]:
for device in ["cuda", "hip", "cpu"]:
backends = DEVICE_MLA_BACKENDS[
device] if use_mla else DEVICE_REGULAR_ATTN_BACKENDS[device]
for name in backends:
block_sizes = DEVICE_MLA_BLOCK_SIZES[device] if use_mla else [
16
]
for block_size in block_sizes:
params.append(
pytest.param(
device,
name,
use_mla,
block_size,
id=
f"{device}_{name}_mla_{str(use_mla)[0]}_blks{block_size}"
))
return params
@pytest.mark.parametrize("device, name, use_mla, block_size",
generate_params())
@pytest.mark.parametrize("use_v1", [True, False])
def test_env(
device: str,
name: str,
use_mla: bool,
block_size: int,
use_v1: bool,
monkeypatch: pytest.MonkeyPatch,
):
"""Test attention backend selection with valid device-backend pairs."""
with monkeypatch.context() as m:
m.setenv("VLLM_USE_V1", "1" if use_v1 else "0")
m.setenv(STR_BACKEND_ENV_VAR, name)
m.setenv("VLLM_MLA_DISABLE", "1" if use_mla else "0")
if device == "cpu":
with patch("vllm.attention.selector.current_platform",
CpuPlatform()):
backend = get_attn_backend(16, torch.float16, torch.float16,
block_size, False)
if use_v1:
assert backend.get_name() == "TORCH_SDPA_VLLM_V1"
else:
assert backend.get_name() == "TORCH_SDPA"
elif device == "hip":
with patch("vllm.attention.selector.current_platform",
RocmPlatform()):
if use_mla:
# Validate HIP MLA backend-block_size combinations
valid_combination = (
(name == "TRITON_MLA" and block_size != 1)
or (name == "ROCM_AITER_MLA" and block_size == 1))
if valid_combination:
backend = get_attn_backend(16,
torch.float16,
torch.float16,
block_size,
False,
use_mla=use_mla)
if use_v1 and name != "TRITON_MLA":
assert backend.get_name() == f"{name}_VLLM_V1"
else:
assert backend.get_name() == name
else:
with pytest.raises(ValueError) as exc_info:
get_attn_backend(16,
torch.float16,
torch.float16,
block_size,
False,
use_mla=use_mla)
assert f"The selected backend, {name}" in str(
exc_info.value)
else:
backend = get_attn_backend(16,
torch.float16,
torch.float16,
block_size,
False,
use_mla=use_mla)
expected = "TRITON_ATTN_VLLM_V1" if use_v1 else "ROCM_FLASH"
assert backend.get_name() == expected
elif device == "cuda":
with patch("vllm.attention.selector.current_platform",
CudaPlatform()):
if use_mla:
if name == "FLASHMLA" and block_size == 64:
from vllm.attention.backends.flashmla import (
is_flashmla_supported)
# only on cuda platforms with specific capability.
is_supported, _ = is_flashmla_supported()
if not is_supported:
# if platform is not supported then skip this case.
pytest.skip()
else:
backend = get_attn_backend(16,
torch.float16,
torch.float16,
block_size,
False,
use_mla=use_mla)
expected = f"{name}_VLLM_V1" if use_v1 else name
assert backend.get_name() == expected
else:
backend = get_attn_backend(16,
torch.float16,
torch.float16,
block_size,
False,
use_mla=use_mla)
expected = ("TRITON_MLA_VLLM_V1"
if use_v1 else "TRITON_MLA")
assert backend.get_name() == expected
elif name == "FLASHINFER":
backend = get_attn_backend(16,
torch.float16,
torch.float16,
block_size,
False,
use_mla=use_mla)
expected = "FLASHINFER_VLLM_V1" if use_v1 else name
assert backend.get_name() == expected
else:
backend = get_attn_backend(16,
torch.float16,
torch.float16,
block_size,
False,
use_mla=use_mla)
expected = "FLASH_ATTN_VLLM_V1" if use_v1 else name
assert backend.get_name() == expected
def test_flash_attn(monkeypatch: pytest.MonkeyPatch):
"""Test FlashAttn validation."""
# TODO: When testing for v1, pipe in `use_v1` as an argument to
# get_attn_backend
with monkeypatch.context() as m:
m.setenv(STR_BACKEND_ENV_VAR, STR_FLASH_ATTN_VAL)
# Unsupported CUDA arch
monkeypatch.setattr(torch.cuda,
"get_device_capability",
lambda _=None: (7, 5))
backend = get_attn_backend(16, torch.float16, None, 16, False)
assert backend.get_name() != STR_FLASH_ATTN_VAL
# Reset the monkeypatch for subsequent tests
monkeypatch.undo()
# Unsupported data type
backend = get_attn_backend(16, torch.float8_e4m3fn, None, 16, False)
assert backend.get_name() != STR_FLASH_ATTN_VAL
# Unsupported kv cache data type
backend = get_attn_backend(16, torch.float16, "fp8", 16, False)
assert backend.get_name() != STR_FLASH_ATTN_VAL
# Unsupported block size
backend = get_attn_backend(16, torch.float16, None, 8, False)
assert backend.get_name() != STR_FLASH_ATTN_VAL
# flash-attn is not installed
import sys
original_module = sys.modules.get('vllm_flash_attn')
monkeypatch.setitem(sys.modules, 'vllm_flash_attn', None)
backend = get_attn_backend(16, torch.float16, None, 16, False)
assert backend.get_name() != STR_FLASH_ATTN_VAL
# Restore the original module if it existed
if original_module is not None:
monkeypatch.setitem(sys.modules, 'vllm_flash_attn',
original_module)
else:
monkeypatch.delitem(sys.modules, 'vllm_flash_attn', raising=False)
# Unsupported head size
backend = get_attn_backend(17, torch.float16, None, 16, False)
assert backend.get_name() != STR_FLASH_ATTN_VAL
# Attention-free models should bypass env and use PlaceholderAttention
backend = get_attn_backend(16, torch.float16, torch.float16, 16, True)
assert backend.get_name() != STR_FLASH_ATTN_VAL
@pytest.mark.parametrize("use_v1", [True, False])
def test_invalid_env(use_v1: bool, monkeypatch: pytest.MonkeyPatch):
with monkeypatch.context() as m, patch(
"vllm.attention.selector.current_platform", CudaPlatform()):
m.setenv("VLLM_USE_V1", "1" if use_v1 else "0")
m.setenv(STR_BACKEND_ENV_VAR, STR_INVALID_VAL)
# Test with head size 32
backend = get_attn_backend(32, torch.float16, None, 16, False)
EXPECTED = "FLASH_ATTN_VLLM_V1" if use_v1 else "FLASH_ATTN"
assert backend.get_name() == EXPECTED
# when block size == 16, backend will fall back to XFORMERS
# this behavior is not yet supported on V1.
if use_v1:
# TODO: support fallback on V1!
# https://github.com/vllm-project/vllm/issues/14524
pass
else:
backend = get_attn_backend(16, torch.float16, None, 16, False)
assert backend.get_name() == "XFORMERS"