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vllm-omni/tests/diffusion/models/boogu_image/test_sp_layout.py
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2026-09-25 16:18:23 +08:00

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Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
"""L1 unit tests for BOOGU's SP shard-layout arithmetic.
These cover the property the model relies on to build attention masks without
communicating: every rank can derive *every* rank's segment bounds from the
global sequence length alone.
"""
import pytest
import torch
from vllm_omni.diffusion.models.boogu_image.sp_layout import (
ShardLayout,
rank_concat_mask_or_none,
)
pytestmark = [pytest.mark.core_model, pytest.mark.cpu, pytest.mark.diffusion]
class TestShardLayout:
def test_padding_and_local_extent(self):
layout = ShardLayout(original_seq_len=5, world_size=2, rank=0)
assert layout.padded_seq_len == 6
assert layout.local_seq_len == 3
assert layout.padding_size == 1
assert layout.bounds(0) == (0, 3)
assert layout.bounds(1) == (3, 6)
def test_valid_lengths_clip_to_each_rank(self):
layout = ShardLayout(original_seq_len=5, world_size=2, rank=0)
# Sample 0 has 5 valid tokens (3 on rank 0, 2 on rank 1); sample 1 has 2.
assert layout.valid_lengths([5, 2], rank=0) == [3, 2]
assert layout.valid_lengths([5, 2], rank=1) == [2, 0]
def test_segment_lengths_split_across_the_boundary(self):
layout = ShardLayout(original_seq_len=5, world_size=2, rank=0)
# Two reference images of 2 and 3 tokens; the second straddles rank 0/1.
assert layout.segment_lengths([[2, 3]], rank=0) == [[2, 1]]
assert layout.segment_lengths([[2, 3]], rank=1) == [[0, 2]]
@pytest.mark.parametrize("world_size", [1, 2, 4])
def test_per_rank_lengths_sum_to_the_global_length(self, world_size):
layout = ShardLayout(original_seq_len=13, world_size=world_size, rank=0)
for global_length in (0, 1, 7, 13):
total = sum(layout.valid_lengths([global_length], rank=r)[0] for r in range(world_size))
assert total == global_length
class TestRankConcatMask:
"""The mask must describe the sequence Ulysses forms after its all-to-all.
That sequence is rank0's local shard followed by rank1's, etc. -- not the
natural global ordering -- because each rank packs [context|ref|noise]
locally before attention.
"""
def test_mask_is_concatenation_of_per_rank_segments(self):
mask = rank_concat_mask_or_none(
[[2], [1]],
capacity=3,
like=torch.zeros(1, 1),
)
# rank 0 contributes [T, T, F], rank 1 contributes [T, F, F]
assert mask.tolist() == [[True, True, False, True, False, False]]
def test_all_valid_mask_is_dropped(self):
assert (
rank_concat_mask_or_none(
[[3], [3]],
capacity=3,
like=torch.zeros(1, 1),
)
is None
)
def test_required_keeps_an_all_valid_mask(self):
mask = rank_concat_mask_or_none(
[[3], [3]],
capacity=3,
like=torch.zeros(1, 1),
required=True,
)
assert mask is not None
assert bool(mask.all())
class TestRankConcatEquivalence:
"""The built mask must equal an all-gather of per-rank local masks.
BOOGU used to hand rank-local masks to the attention layer, which
all-gathered them into the global sequence. The model now builds that
global mask directly -- saving one collective per attention call -- so the
two constructions must agree exactly. This is asserted structurally
because the end-to-end SP1-vs-SP2 comparison is numerically insensitive to
masking (a run with masks entirely disabled still matches to ~5e-7).
"""
@staticmethod
def _all_gather_of_local_masks(per_rank_lengths, capacity):
"""What the deleted `dist.all_gather` path used to produce."""
batch_size = len(per_rank_lengths[0])
local_masks = []
for lengths in per_rank_lengths:
local = torch.zeros(batch_size, capacity, dtype=torch.bool)
for i, length in enumerate(lengths):
local[i, :length] = True
local_masks.append(local)
return torch.cat(local_masks, dim=1)
@pytest.mark.parametrize(
("global_len", "world_size", "sample_lengths"),
[
(5, 2, [5, 2]),
(8, 2, [8, 1]),
(13, 4, [13, 7, 0]),
(16, 4, [16]),
(7, 1, [7, 3]),
],
)
def test_matches_all_gather_of_local_masks(self, global_len, world_size, sample_lengths):
layout = ShardLayout(original_seq_len=global_len, world_size=world_size, rank=0)
per_rank = [layout.valid_lengths(sample_lengths, rank=r) for r in range(world_size)]
built = rank_concat_mask_or_none(
per_rank,
layout.local_seq_len,
like=torch.zeros(1, 1),
required=True,
)
assert torch.equal(built, self._all_gather_of_local_masks(per_rank, layout.local_seq_len))