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vllm-omni/tests/diffusion/models/helios/test_helios_usp_shard.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
"""Unit tests for Helios per-component sequence splitting.
These tests verify the manual sharding logic that replaces the broken
rope/blocks.0 hooks in the Helios ``_sp_plan``. They exercise the *real*
``HeliosTransformer3DModel._sp_split_seq`` (the parallel-state getters it
imports lazily inside the method body are monkeypatched), so the model-side
helper cannot drift silently from what is tested. For the multi-rank
mechanism around the helper (manual ``_sp_shard_depth`` bump, attn1/attn2
parallel strategy, ws=2 vs ws=1 output equivalence) see
``test_helios_usp_2rank.py``.
Coverage:
1. USP disabled (ws == 1) returns the tensor unchanged.
2. Divisible split gives each rank the expected slice.
3. Non-divisible split pads with replicated tokens (no crash).
4. Per-component split: history + current tokens are distributed so
that *both* ranks receive some current tokens (no mosaic regression).
5. Edge cases: 1-D tensor, empty seq, 4-D tensor.
"""
from collections.abc import Iterator
from contextlib import contextmanager
import pytest
import torch
import vllm_omni.diffusion.distributed.parallel_state as sp_parallel_state
from vllm_omni.diffusion.models.helios.helios_transformer import HeliosTransformer3DModel
pytestmark = [pytest.mark.core_model, pytest.mark.diffusion, pytest.mark.cpu]
@contextmanager
def _fake_sp_state(ws: int, rank: int) -> Iterator[None]:
"""Patch the parallel-state getters used by the real helper.
``_sp_split_seq`` imports these names from the module *inside* its
function body, so replacing the module attributes takes effect.
"""
prev_ws = sp_parallel_state.get_sequence_parallel_world_size
prev_rank = sp_parallel_state.get_sequence_parallel_rank
sp_parallel_state.get_sequence_parallel_world_size = lambda: ws
sp_parallel_state.get_sequence_parallel_rank = lambda: rank
try:
yield
finally:
sp_parallel_state.get_sequence_parallel_world_size = prev_ws
sp_parallel_state.get_sequence_parallel_rank = prev_rank
def _sp_split_seq(x: torch.Tensor, ws: int, rank: int) -> torch.Tensor:
"""Call the real model-side helper without constructing a model."""
with _fake_sp_state(ws, rank):
return HeliosTransformer3DModel._sp_split_seq(None, x)
# ---------------------------------------------------------------------------
# Tests
# ---------------------------------------------------------------------------
class TestSpSplitSeqDisabled:
"""When USP is off (ws == 1) the helper must be a no-op."""
def test_ws1_returns_unchanged(self):
x = torch.randn(2, 100, 64)
out = _sp_split_seq(x, ws=1, rank=0)
assert torch.equal(out, x)
assert out is x
class TestSpSplitSeqDivisible:
"""Divisible sequences: each rank gets exactly seq_len / ws tokens."""
def test_each_rank_gets_correct_slice(self):
for ws in [2, 4, 8]:
seq_len = ws * 10
x = torch.arange(seq_len * 4).float().reshape(1, seq_len, 4)
for rank in range(ws):
out = _sp_split_seq(x, ws=ws, rank=rank)
n = seq_len // ws
expected = x[:, rank * n : (rank + 1) * n, :]
assert out.shape == (1, n, 4)
assert torch.equal(out, expected)
def test_output_is_contiguous(self):
x = torch.randn(1, 20, 8)
out = _sp_split_seq(x, ws=2, rank=0)
assert out.is_contiguous()
class TestSpSplitSeqNonDivisible:
"""Non-divisible sequences are padded with replicated tokens."""
def test_non_divisible_pads_instead_of_crash(self):
"""400x272 → 9*25*17 = 3825 tokens, USP=2 → not divisible.
Should pad to 3826 and split, not crash."""
x = torch.randn(1, 3825, 8)
for rank in range(2):
out = _sp_split_seq(x, ws=2, rank=rank)
# 3825 → pad 1 → 3826 → /2 = 1913
assert out.shape[1] == 1913
def test_non_divisible_pads_with_replicated_last_token(self):
"""Verify the padding is the replicated last token, not zeros."""
x = torch.randn(1, 7, 4) # 7 % 2 = 1, pad 1
last_token = x[:, -1:, :].clone()
out = _sp_split_seq(x, ws=2, rank=0)
# rank 0 gets tokens [0:4] (first 4 of the padded 8)
assert out.shape == (1, 4, 4)
# rank 1 gets tokens [4:8] — token 7 (the padded one) = last token
out1 = _sp_split_seq(x, ws=2, rank=1)
assert out1.shape == (1, 4, 4)
assert torch.equal(out1[:, -1:, :], last_token)
def test_non_divisible_7_4(self):
"""7 tokens, ws=4 → pad 1 → 8 → /4 = 2 per rank."""
x = torch.randn(1, 7, 8)
for rank in range(4):
out = _sp_split_seq(x, ws=4, rank=rank)
assert out.shape[1] == 2
def test_non_divisible_15_4(self):
"""15 tokens, ws=4 → pad 1 → 16 → /4 = 4 per rank."""
x = torch.randn(1, 15, 8)
for rank in range(4):
out = _sp_split_seq(x, ws=4, rank=rank)
assert out.shape[1] == 4
class TestSpSplitSeqPerComponent:
"""Simulate Helios forward: split current + history components so that
*both* ranks receive some current tokens (no mosaic regression)."""
def test_both_ranks_get_current_tokens(self):
"""history=2400, current=540, ws=2.
After per-component split, each rank must have > 0 current tokens."""
current = torch.randn(1, 540, 64)
history = torch.randn(1, 2400, 64)
for rank in range(2):
cur_local = _sp_split_seq(current, ws=2, rank=rank)
hist_local = _sp_split_seq(history, ws=2, rank=rank)
assert cur_local.shape[1] > 0, f"Rank {rank} received 0 current tokens"
assert cur_local.shape[1] == 270 # 540 / 2
assert hist_local.shape[1] == 1200 # 2400 / 2
original_context_length = cur_local.shape[1]
assert original_context_length > 0 # no mosaic regression
def test_gather_restores_full_current(self):
"""After splitting current into 2 ranks, simulating proj_out
gather must restore the full current sequence length so that
the original unpatchify reshape succeeds."""
current = torch.randn(1, 540, 64)
local_chunks = [_sp_split_seq(current, ws=2, rank=rank) for rank in range(2)]
gathered = torch.cat(local_chunks, dim=1)
assert gathered.shape[1] == 540 # full current restored
def test_gather_with_padding_truncates_correctly(self):
"""Non-divisible current (3825) → pad to 3826 → split →
gather → 3826. Slice to 3825 for unpatchify."""
current = torch.randn(1, 3825, 64)
local_chunks = [_sp_split_seq(current, ws=2, rank=rank) for rank in range(2)]
gathered = torch.cat(local_chunks, dim=1)
assert gathered.shape[1] == 3826 # padded size
# Simulate the slice before unpatchify
expected_seq = 3825
if gathered.shape[1] > expected_seq:
gathered = gathered[:, :expected_seq, :]
assert gathered.shape[1] == 3825 # correct after slice
def test_rotary_emb_aligned_with_hidden_states(self):
"""rotary_emb and hidden_states must be split at the same
positions so that tokens align inside the attention layer."""
hidden = torch.randn(1, 540, 5120)
rotary = torch.randn(1, 540, 256)
for rank in range(2):
h_local = _sp_split_seq(hidden, ws=2, rank=rank)
r_local = _sp_split_seq(rotary, ws=2, rank=rank)
assert h_local.shape[1] == r_local.shape[1]
def test_whole_split_causes_mosaic_but_per_component_does_not(self):
"""Demonstrates why per-component split is needed:
with whole split (simulated), rank 0 gets 0 current tokens;
with per-component split, both ranks get current tokens."""
history = torch.randn(1, 2400, 64)
current = torch.randn(1, 540, 64)
full = torch.cat([history, current], dim=1) # 2940
# Whole split (the OLD broken behavior)
whole_n = full.shape[1] // 2 # 1470
rank0_whole = full[:, :whole_n, :]
rank0_current = rank0_whole.shape[1] - 2400 # negative → 0 current
assert rank0_current <= 0, "Whole split should give rank 0 no current"
# Per-component split (the NEW correct behavior)
for rank in range(2):
cur_local = _sp_split_seq(current, ws=2, rank=rank)
assert cur_local.shape[1] == 270 # both ranks have current
class TestSpSplitSeqEdgeCases:
"""Edge cases that should not crash or silently misbehave."""
def test_1d_tensor_skipped(self):
"""1-D tensors must be returned unchanged (dim < 2 guard)."""
x = torch.randn(100)
out = _sp_split_seq(x, ws=2, rank=0)
assert torch.equal(out, x)
def test_empty_seq_skipped(self):
"""Empty sequence dimension must be returned unchanged."""
x = torch.randn(1, 0, 64)
out = _sp_split_seq(x, ws=2, rank=0)
assert out.shape == x.shape
def test_4d_tensor_split_on_dim1(self):
"""4-D tensor [B, S, H, D] should split along dim=1."""
x = torch.randn(1, 20, 8, 32)
out = _sp_split_seq(x, ws=2, rank=1)
assert out.shape == (1, 10, 8, 32)