vllm/tests/v1/attention/test_attention_splitting.py
Sage Moore 0edaf752d7
[Attention][DBO] Add support for "splitting" the CommonAttentionMetadata (#21153)
Signed-off-by: Sage Moore <sage@neuralmagic.com>
2025-08-01 19:47:53 -07:00

158 lines
5.6 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import pytest
import torch
from tests.v1.attention.test_attention_backends import BATCH_SPECS
from tests.v1.attention.utils import create_common_attn_metadata
from vllm.v1.attention.backends.utils import (UbatchSlice,
_make_metadata_with_slice,
slice_query_start_locs,
split_attn_metadata)
@pytest.fixture
def sample_query_start_loc():
"""Sample query_start_loc tensor for testing"""
return torch.tensor([0, 5, 12, 20, 35, 50])
def test_basic_slice_middle(sample_query_start_loc):
"""Test slicing from middle of tensor"""
req_slice = slice(1, 3) # slice from index 1 to 3
result = slice_query_start_locs(sample_query_start_loc, req_slice)
expected = torch.tensor([0, 7, 15])
assert torch.equal(result, expected)
def test_slice_from_beginning(sample_query_start_loc):
"""Test slicing from the beginning of tensor"""
req_slice = slice(0, 2) # slice from index 0 to 2
result = slice_query_start_locs(sample_query_start_loc, req_slice)
expected = torch.tensor([0, 5, 12])
assert torch.equal(result, expected)
def test_slice_to_end(sample_query_start_loc):
"""Test slicing to the end of tensor"""
req_slice = slice(3, 5) # slice from index 3 to 5 (last index)
result = slice_query_start_locs(sample_query_start_loc, req_slice)
expected = torch.tensor([0, 15, 30])
assert torch.equal(result, expected)
def test_single_element_slice(sample_query_start_loc):
"""Test slice that results in single element"""
req_slice = slice(2, 3) # slice from index 2 to 3
result = slice_query_start_locs(sample_query_start_loc, req_slice)
expected = torch.tensor([0, 8])
assert torch.equal(result, expected)
def test_full_tensor_slice(sample_query_start_loc):
"""Test slicing the entire tensor"""
req_slice = slice(0, 5) # slice entire tensor
result = slice_query_start_locs(sample_query_start_loc, req_slice)
expected = torch.tensor([0, 5, 12, 20, 35, 50])
assert torch.equal(result, expected)
def test_slice_bounds_edge_cases(sample_query_start_loc):
# Test slice that goes exactly to the last element
req_slice = slice(4, 5) # Last index
result = slice_query_start_locs(sample_query_start_loc, req_slice)
expected = torch.tensor([0, 15])
assert torch.equal(result, expected)
@pytest.fixture
def small_decode_metadata():
"""Create metadata for small decode batch"""
batch_spec = BATCH_SPECS["small_decode"]
device = torch.device("cpu")
return create_common_attn_metadata(batch_spec,
block_size=16,
device=device)
@pytest.fixture
def large_decode_metadata():
"""Create metadata for small decode batch"""
batch_spec = BATCH_SPECS["large_decode"]
device = torch.device("cpu")
return create_common_attn_metadata(batch_spec,
block_size=16,
device=device)
@pytest.fixture
def mixed_small_metadata():
"""Create metadata for mixed small batch"""
batch_spec = BATCH_SPECS["mixed_small"]
device = torch.device("cpu")
return create_common_attn_metadata(batch_spec,
block_size=16,
device=device)
# Tests for _make_metadata_with_slice
def test_make_metadata_with_slice_decode_batch(small_decode_metadata):
"""Test slicing decode batch metadata"""
# Split first request only
ubatch_slice = UbatchSlice(slice(0, 1), slice(0, 1))
result = _make_metadata_with_slice(ubatch_slice, small_decode_metadata)
# Check sliced results
assert result.num_reqs == 1 # slice(0, 1) gives 1 requests
assert result.num_actual_tokens == 1 # slice(0, 1) gives 1 token
assert result.max_query_len == 1
assert torch.equal(result.query_start_loc, torch.tensor([0, 1]))
assert torch.equal(result.seq_lens, torch.tensor([32]))
def test_make_metadata_with_slice_mixed_batch(mixed_small_metadata):
"""Test slicing mixed batch metadata"""
ubatch_slice = UbatchSlice(slice(1, 3),
slice(1, 7)) # Requests 1-3, tokens 1-7
result = _make_metadata_with_slice(ubatch_slice, mixed_small_metadata)
assert result.num_reqs == 2 # slice(1, 3) gives 2 requests
assert result.num_actual_tokens == 6 # slice(1, 7) gives 6 tokens
assert result.max_query_len == 5
assert torch.equal(result.query_start_loc, torch.tensor([0, 1, 6]))
assert torch.equal(result.seq_lens, torch.tensor([40, 48]))
def test_split_attn_metadata_decode_batch(large_decode_metadata):
"""Test splitting decode batch into two equal parts"""
num_tokens = large_decode_metadata.num_reqs
mid_point = num_tokens // 2
ubatch_slices = [
UbatchSlice(slice(0, mid_point), slice(0, mid_point)),
UbatchSlice(slice(mid_point, num_tokens), slice(mid_point,
num_tokens)),
]
results = split_attn_metadata(ubatch_slices, large_decode_metadata)
assert len(results) == 2
# Check first split
assert results[0].num_reqs == mid_point
assert results[0].num_actual_tokens == mid_point
assert torch.equal(results[0].seq_lens, torch.tensor([2048] * mid_point))
# Check second split
assert results[1].num_reqs == mid_point
assert results[1].num_actual_tokens == mid_point
assert torch.equal(results[1].seq_lens, torch.tensor([2048] * mid_point))