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vllm-omni/tests/diffusion/ar_diffusion/test_kv_orchestration.py
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# SPDX-License-Identifier: Apache-2.0
"""Tests for ARDiffusionKVCache — the engine-level KV orchestration body (Phase 1)."""
import pytest
import torch
from vllm_omni.experimental.ar_diffusion.capability import ARDiffusionKVBranchSpec
from vllm_omni.experimental.ar_diffusion.kv_cache import ARDiffusionKVCache, ARDiffusionKVConfig
from vllm_omni.experimental.ar_diffusion.kv_cache.state import ARDiffusionKVState
pytestmark = [pytest.mark.core_model, pytest.mark.diffusion, pytest.mark.cpu]
DIMS = dict(
num_layers=2,
num_kv_heads=4,
head_size=64,
dtype=torch.float16,
block_size=16,
kv_branches=(ARDiffusionKVBranchSpec("positive", 0), ARDiffusionKVBranchSpec("negative", 1)),
session_capacity=2,
)
def make_cache(*, chunk_size=16, window_chunks=2, available_bytes=1 << 24):
cfg = ARDiffusionKVConfig(enable=True, chunk_size=chunk_size, window_chunks=window_chunks)
return ARDiffusionKVCache(cfg, max_model_len=4096, available_bytes=available_bytes, **DIMS)
def test_requires_enabled_config():
with pytest.raises(ValueError):
ARDiffusionKVCache(ARDiffusionKVConfig(enable=False), max_model_len=256, available_bytes=1 << 20, **DIMS)
def test_requires_bounded_window():
cfg = ARDiffusionKVConfig(enable=True, chunk_size=16, window_chunks=None)
with pytest.raises(ValueError):
ARDiffusionKVCache(cfg, max_model_len=256, available_bytes=1 << 20, **DIMS)
def test_full_request_lifecycle_and_eviction():
"""begin -> per-chunk allocate/slots/commit over a long rollout -> free.
Exercises the orchestrator end-to-end and asserts the chunk window bounds
memory (pool plateaus) and frees cleanly.
"""
kv = make_cache(chunk_size=16, window_chunks=2)
free_total = kv.manager.block_pool.get_num_free_blocks()
adapter = kv.begin_request("req-0")
free_after = []
for k in range(10):
block_table = kv.allocate_chunk(adapter)
slots = kv.chunk_write_slots(adapter)
# Slots target real blocks in this chunk's table; length == chunk_size.
assert len(slots) == kv.spec.chunk_size
used = {int(s) // kv.block_size for s in slots}
assert kv.null_block_id not in used
assert used <= set(block_table)
# Allocation may transiently add one in-flight chunk.
assert len(kv.window_block_ids(adapter)) <= kv.spec.window_chunks + 1
kv.commit_chunk(adapter)
# A successful commit immediately prunes physical ownership.
assert len(kv.window_block_ids(adapter)) <= kv.spec.window_chunks
free_after.append(kv.manager.block_pool.get_num_free_blocks())
# Pool memory plateaus once the window is full (eviction recycles blocks).
assert free_after[-1] == free_after[kv.spec.window_chunks - 1]
kv.end_request(adapter)
assert kv.manager.block_pool.get_num_free_blocks() == free_total
def test_num_computed_advances_per_chunk():
kv = make_cache(chunk_size=16, window_chunks=2)
a = kv.begin_request("r")
assert a.num_computed_tokens == 0
kv.allocate_chunk(a)
kv.commit_chunk(a)
assert a.num_computed_tokens == 16
kv.end_request(a)
def test_state_close_frees_both_branch_blocks():
"""ARDiffusionKVState.close() returns both CFG kv_branches' pool blocks to the pool.
This is the primitive the runner's LRU eviction relies on: when a session is
evicted, close() must free the blocks both adapters hold, or session churn
leaks pool ownership (review P1).
"""
from vllm_omni.experimental.ar_diffusion.kv_cache.state import ARDiffusionKVState
kv = make_cache(chunk_size=16, window_chunks=2)
free_total = kv.manager.block_pool.get_num_free_blocks()
pos = kv.begin_request("bde__s")
neg = kv.begin_request("bde__s__neg")
state = ARDiffusionKVState(
kv,
"s",
{"positive": pos, "negative": neg},
num_layers=kv.num_layers,
)
for _ in range(3):
for adapter in (pos, neg):
kv.allocate_chunk(adapter)
kv.commit_chunk(adapter)
# Both kv_branches hold resident blocks now.
assert kv.manager.block_pool.get_num_free_blocks() < free_total
state.close()
# All blocks returned — no leak across an evicted session.
assert kv.manager.block_pool.get_num_free_blocks() == free_total
@pytest.mark.parametrize(
"frames_per_call,block_size,max_model_len,num_calls",
[(1, 16, 113, 1000), (3, 16, 113, 1000), (3, 1560, 1 << 20, 241)],
ids=["single-frame", "three-frame", "lingbot-two-minutes"],
)
@pytest.mark.parametrize("sink_chunks,reset_at_boundary", [(0, False), (2, False), (0, True), (2, True)])
def test_rollout_keeps_metadata_bounded(
frames_per_call, block_size, max_model_len, num_calls, sink_chunks, reset_at_boundary
):
"""Long rollouts retain exact global-position K/V with bounded storage indices."""
kv = ARDiffusionKVCache(
ARDiffusionKVConfig(
enable=True,
chunk_size=block_size,
window_chunks=3,
sink_chunks=sink_chunks,
reset_at_boundary=reset_at_boundary,
),
num_layers=1,
num_kv_heads=1,
head_size=4,
dtype=torch.float32,
block_size=block_size,
max_model_len=max_model_len,
available_bytes=1 << 24,
kv_branches=(ARDiffusionKVBranchSpec("main", 0),),
session_capacity=1,
frames_per_block=frames_per_call,
device=torch.device("cpu"),
)
adapter = kv.begin_request("long-rollout")
state = ARDiffusionKVState(kv, "long-rollout", {"main": adapter}, num_layers=1)
free_total = kv.manager.block_pool.get_num_free_blocks()
pool_shape = kv.key_cache(0).shape
retained_frames = sink_chunks + (0 if reset_at_boundary else 3)
for call_index in range(num_calls):
start = call_index * frames_per_call * block_size
stop = start + frames_per_call * block_size
if frames_per_call == 1:
kv.allocate_chunk(adapter)
slots = kv.chunk_write_slots(adapter)
else:
context = state.get_kv_caches("main", seq_len=stop - start, commit_current=True)[0].forward_ctx
context.ensure_video_slots(torch.device("cpu"))
slots = context.current_video_slot_mapping
assert len(kv.block_table(adapter)) <= retained_frames + frames_per_call
values = torch.arange(start, stop, dtype=torch.float32).view(-1, 1, 1).expand(-1, 1, 4)
kv.key_cache(0).flatten(0, 1)[slots] = values
kv.value_cache(0).flatten(0, 1)[slots] = -values
if frames_per_call == 1:
kv.commit_chunk(adapter)
else:
state.commit_paged_context("main")
assert state._committed["main"] == stop
sink_end = min(stop, sink_chunks * block_size)
tail_start = stop if reset_at_boundary else max(sink_end, stop - 3 * block_size)
expected = torch.cat((torch.arange(sink_end), torch.arange(tail_start, stop))).float()
expected = expected.view(-1, 1, 1).expand(-1, 1, 4)
resident = kv.window_block_ids(adapter)
torch.testing.assert_close(kv.key_cache(0)[resident].flatten(0, 1), expected)
torch.testing.assert_close(kv.value_cache(0)[resident].flatten(0, 1), -expected)
assert adapter.completed_chunks * block_size == stop
assert adapter.absolute_num_computed_tokens == stop
assert len(kv.block_table(adapter)) <= retained_frames
assert adapter.num_computed_tokens <= retained_frames * block_size
assert kv.key_cache(0).shape == pool_shape
assert free_total - kv.manager.block_pool.get_num_free_blocks() == min(stop // block_size, retained_frames)
state.reset()
fresh = state.adapter("main")
assert fresh.compacted_tokens == fresh.absolute_num_computed_tokens == fresh.num_computed_tokens == 0
assert kv.block_table(fresh) == []
assert kv.manager.block_pool.get_num_free_blocks() == free_total
kv.allocate_chunk(fresh)
assert len(kv.chunk_write_slots(fresh)) == block_size
state.close()
assert kv.manager.block_pool.get_num_free_blocks() == free_total
def test_compaction_offsets_are_request_local():
kv = make_cache()
free_total = kv.manager.block_pool.get_num_free_blocks()
first, second = kv.begin_request("first"), kv.begin_request("second")
for index in range(8):
kv.allocate_chunk(first)
kv.commit_chunk(first)
if index in (0, 4):
kv.allocate_chunk(second)
kv.commit_chunk(second)
assert first.absolute_num_computed_tokens == 8 * 16
assert first.compacted_tokens == 6 * 16
assert second.absolute_num_computed_tokens == 2 * 16
assert second.compacted_tokens == 0
assert first.num_computed_tokens == second.num_computed_tokens == 2 * 16
assert set(kv.block_table(first)).isdisjoint(kv.block_table(second))
kv.end_request(first)
kv.end_request(second)
group = kv.manager.coordinator.single_type_managers[0]
assert not group.req_to_blocks and not group.num_cached_block
assert kv.manager.block_pool.get_num_free_blocks() == free_total