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vllm-omni/tests/diffusion/models/minimax_h3/test_vsa_layout.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
import math
import sys
import types
from typing import Any
import pytest
import torch
from vllm_omni.diffusion.attention.backends.abstract import (
AttentionMetadata,
PackedPaddingMetadata,
VideoTokenLayout,
VideoTokenSpan,
)
from vllm_omni.diffusion.models.minimax_h3.attention.fastvideo_h3 import (
MiniMaxH3VSAImpl,
_get_h3_tile_metadata,
)
pytestmark = [pytest.mark.core_model, pytest.mark.diffusion, pytest.mark.cpu]
def _h3_metadata(prefix_segments, video_shape, *, gate=None, packed_padding=None):
extra: dict[str, Any] = {
"vsa_h3_prefix_segments": prefix_segments,
}
if gate is not None:
extra["gate_compress"] = gate
return AttentionMetadata(
packed_padding=packed_padding,
video_layout=VideoTokenLayout(
used_len=sum(prefix_segments) + math.prod(video_shape),
video_spans=(VideoTokenSpan(start=sum(prefix_segments), latent_grid=video_shape, role="target"),),
),
extra=extra,
)
def _fake_block_sparse_kernel(monkeypatch, calls):
"""Stand in for fastvideo_kernel.block_sparse_attn with a mask-obeying SDPA."""
def block_sparse_attn(q, k, v, block_map, variable_block_sizes):
calls["block_map"] = block_map.clone()
calls["variable_block_sizes"] = variable_block_sizes.tolist()
calls["q_shape"] = tuple(q.shape)
blocks = block_map.shape[-1]
assert blocks * 64 == q.shape[2]
# Expand the per-block map to a per-token mask so the stand-in honours
# the sparsity contract the real kernel implements, and drop the rows
# each partial block pads with, which the real kernel skips through
# variable_block_sizes.
token_mask = block_map.repeat_interleave(64, dim=-1).repeat_interleave(64, dim=-2)
within = torch.arange(64, device=q.device)[None, :] < variable_block_sizes[:, None]
token_mask = token_mask & within.reshape(1, 1, 1, -1)
out = torch.nn.functional.scaled_dot_product_attention(q.float(), k.float(), v.float(), attn_mask=token_mask)
return out.to(q.dtype), None
module = types.ModuleType("fastvideo_kernel.block_sparse_attn")
setattr(module, "block_sparse_attn", block_sparse_attn)
monkeypatch.setitem(sys.modules, "fastvideo_kernel", types.ModuleType("fastvideo_kernel"))
monkeypatch.setitem(sys.modules, "fastvideo_kernel.block_sparse_attn", module)
def _h3_impl(**backend_kwargs):
kwargs = {"topk": 1, "min_seq_len": 1, "disable_when_sp_active": False}
kwargs.update(backend_kwargs)
return MiniMaxH3VSAImpl(num_heads=2, head_size=8, softmax_scale=8**-0.5, backend_kwargs=kwargs)
def test_h3_forward_tiles_untiles_and_restores_the_original_row_order(monkeypatch):
calls: dict[str, Any] = {}
_fake_block_sparse_kernel(monkeypatch, calls)
impl = _h3_impl(topk=64)
prefix_segments, video_shape = (5, 70), (2, 4, 4)
seq_len = sum(prefix_segments) + 2 * 4 * 4
torch.manual_seed(0)
query = torch.randn(1, seq_len, 2, 8, dtype=torch.bfloat16)
output = impl.forward_cuda(query, query, query, _h3_metadata(prefix_segments, video_shape))
assert output.shape == query.shape
# topk covers every video block, so the block map is dense and the tiled
# kernel must reproduce plain attention over the same rows.
reference = torch.nn.functional.scaled_dot_product_attention(
*(x.float().transpose(1, 2) for x in (query, query, query))
).transpose(1, 2)
torch.testing.assert_close(output.float(), reference, atol=2e-2, rtol=2e-2)
# 5 + 70 splits into segment-pure 5 | 64 | 6, then one (2, 4, 4) video tile.
assert calls["variable_block_sizes"] == [5, 64, 6, 32]
def test_h3_forward_keeps_prefix_dense_and_selects_top_k_video_tiles(monkeypatch):
calls: dict[str, Any] = {}
_fake_block_sparse_kernel(monkeypatch, calls)
impl = _h3_impl(topk=1)
prefix_segments, video_shape = (5,), (8, 4, 4)
seq_len = 5 + 8 * 4 * 4
torch.manual_seed(0)
query = torch.randn(1, seq_len, 2, 8, dtype=torch.bfloat16)
impl.forward_cuda(query, query, query, _h3_metadata(prefix_segments, video_shape))
# 1 prefix block + 2 video blocks. The odd count is padded to an even one
# for the paired-CTA kernel contract, and the Triton route slices that
# transport-only partner off again before launching.
block_map = calls["block_map"]
assert block_map.shape[-1] == 3
assert calls["variable_block_sizes"] == [5, 64, 64]
assert block_map[:, :, :1, :].all(), "prefix queries stay dense"
assert block_map[..., :1].all(), "prefix keys are exempt from selection"
assert (block_map[:, :, 1:, 1:].sum(dim=-1) == 1).all(), "one video tile per video query"
# The same odd geometry must still untile back onto the original rows.
dense = _h3_impl(topk=64).forward_cuda(query, query, query, _h3_metadata(prefix_segments, video_shape))
reference = torch.nn.functional.scaled_dot_product_attention(
*(x.float().transpose(1, 2) for x in (query, query, query))
).transpose(1, 2)
torch.testing.assert_close(dense.float(), reference, atol=2e-2, rtol=2e-2)
def test_h3_forward_applies_the_learned_compression_gate(monkeypatch):
_fake_block_sparse_kernel(monkeypatch, {})
impl = _h3_impl(topk=64)
prefix_segments, video_shape = (5,), (2, 4, 4)
seq_len = 5 + 2 * 4 * 4
torch.manual_seed(0)
query = torch.randn(1, seq_len, 2, 8, dtype=torch.bfloat16)
without_gate = impl.forward_cuda(query, query, query, _h3_metadata(prefix_segments, video_shape))
zero_gate = torch.zeros_like(query)
with_zero_gate = impl.forward_cuda(query, query, query, _h3_metadata(prefix_segments, video_shape, gate=zero_gate))
live_gate = torch.full_like(query, 0.5)
with_live_gate = impl.forward_cuda(query, query, query, _h3_metadata(prefix_segments, video_shape, gate=live_gate))
torch.testing.assert_close(with_zero_gate.float(), without_gate.float())
assert not torch.allclose(with_live_gate.float(), without_gate.float())
def test_h3_forward_restores_rows_the_packed_padding_excludes(monkeypatch):
_fake_block_sparse_kernel(monkeypatch, {})
impl = _h3_impl(topk=64)
prefix_segments, video_shape = (5,), (2, 4, 4)
valid = 5 + 2 * 4 * 4
torch.manual_seed(0)
query = torch.randn(1, valid + 24, 2, 8, dtype=torch.bfloat16)
padding = PackedPaddingMetadata(
q_length=valid,
kv_length=valid,
cu_seqlens_q=torch.tensor([0, valid], dtype=torch.int32),
cu_seqlens_k=torch.tensor([0, valid], dtype=torch.int32),
)
output = impl.forward_cuda(query, query, query, _h3_metadata(prefix_segments, video_shape, packed_padding=padding))
assert output.shape == query.shape
assert torch.count_nonzero(output[:, valid:]) == 0
def test_h3_geometry_keeps_prefix_segments_pure_and_tiles_video_3d():
partition, sizes, non_pad, untile, prefix_blocks, video_blocks = _get_h3_tile_metadata(
(5, 70, 9), (5, 6, 6), torch.device("cpu")
)
assert sizes[:4].tolist() == [5, 64, 6, 9]
assert prefix_blocks == 4
assert video_blocks == 8
assert int(sizes.sum()) == 5 + 70 + 9 + 5 * 6 * 6
assert partition.numel() == non_pad.numel() == untile.numel() == int(sizes.sum())
@pytest.mark.parametrize("fallback_on_error", [False, True])
def test_h3_kernel_failure_preserves_fallback_policy(monkeypatch, fallback_on_error):
impl = _h3_impl(fallback_on_error=fallback_on_error)
query = torch.randn(1, 37, 2, 8)
metadata = _h3_metadata((5,), (2, 4, 4))
def fail(*args, **kwargs):
raise RuntimeError("kernel failure")
monkeypatch.setattr(impl, "_forward_h3", fail)
monkeypatch.setattr(impl.sdpa_fallback, "forward", impl.sdpa_fallback.forward_cuda)
if fallback_on_error:
output = impl.forward_cuda(query, query, query, metadata)
expected = impl.sdpa_fallback.forward_cuda(query, query, query, metadata)
torch.testing.assert_close(output, expected, rtol=0, atol=0)
else:
with pytest.raises(RuntimeError, match="kernel failure"):
impl.forward_cuda(query, query, query, metadata)
def test_h3_accelerator_failure_is_not_swallowed(monkeypatch):
impl = _h3_impl(fallback_on_error=True)
query = torch.randn(1, 37, 2, 8)
def fail(*args, **kwargs):
raise torch.AcceleratorError("device failure")
monkeypatch.setattr(impl, "_forward_h3", fail)
with pytest.raises(torch.AcceleratorError, match="device failure"):
impl.forward_cuda(query, query, query, _h3_metadata((5,), (2, 4, 4)))
def test_h3_without_layout_delegates_to_shared_backend(monkeypatch):
from vllm_omni.diffusion.attention.backends.fastvideo_vsa import FastVideoVSAImpl
impl = _h3_impl()
query = torch.randn(1, 37, 2, 8)
metadata = AttentionMetadata()
expected = torch.empty_like(query)
calls = []
def forward(self, q, k, v, attn_metadata):
calls.append((self, q, k, v, attn_metadata))
return expected
monkeypatch.setattr(FastVideoVSAImpl, "forward_cuda", forward)
assert impl.forward_cuda(query, query, query, metadata) is expected
assert len(calls) == 1
assert all(actual is wanted for actual, wanted in zip(calls[0], (impl, query, query, query, metadata)))