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[KV Offload] Clean up ARC/LRU refactoring leftovers: group ARC tests and fix stale comment (#38217)

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Signed-off-by: Ronen Schaffer <ronen.schaffer@ibm.com>
This commit is contained in:
Ronen Schaffer
2026-04-07 15:14:45 +03:00
committed by GitHub
parent 0be9516ea4
commit 7c139ab23f
2 changed files with 239 additions and 276 deletions
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510
tests/v1/kv_offload/test_cpu_manager.py
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@@ -15,6 +15,7 @@ from vllm.v1.kv_offload.abstract import (
from vllm.v1.kv_offload.cpu.manager import CPUOffloadingManager
from vllm.v1.kv_offload.cpu.policies.arc import ARCCachePolicy
from vllm.v1.kv_offload.mediums import CPULoadStoreSpec
from vllm.v1.kv_offload.reuse_manager import FilterReusedOffloadingManager
@dataclass
@@ -243,335 +244,300 @@ def test_cpu_manager():
)
def test_arc_manager_basic():
"""
Tests CPUOffloadingManager with arc policy.
Verifies that ARC handles store, load, and lookup operations correctly.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=4, cache_policy="arc", enable_events=True
)
arc_policy = arc_manager._policy
assert isinstance(arc_policy, ARCCachePolicy)
class TestARCPolicy:
"""Unit tests for CPUOffloadingManager with ARC eviction policy."""
# prepare store [1, 2]
prepare_store_output = arc_manager.prepare_store(to_hashes([1, 2]))
verify_store_output(
prepare_store_output,
ExpectedPrepareStoreOutput(
block_hashes_to_store=[1, 2],
store_block_ids=[0, 1],
block_hashes_evicted=[],
),
)
def _make_manager(
self, num_blocks: int = 4, enable_events: bool = True
) -> tuple[CPUOffloadingManager, ARCCachePolicy]:
manager = CPUOffloadingManager(
block_size=256,
num_blocks=num_blocks,
cache_policy="arc",
enable_events=enable_events,
)
policy = manager._policy
assert isinstance(policy, ARCCachePolicy)
return manager, policy
# lookup [1, 2] -> not ready
assert arc_manager.lookup(to_hashes([1, 2])) == 0
def test_basic(self):
"""
Tests CPUOffloadingManager with arc policy.
Verifies that ARC handles store, load, and lookup operations correctly.
"""
cpu_manager, arc_policy = self._make_manager()
# no events so far
assert list(arc_manager.take_events()) == []
# prepare store [1, 2]
prepare_store_output = cpu_manager.prepare_store(to_hashes([1, 2]))
verify_store_output(
prepare_store_output,
ExpectedPrepareStoreOutput(
block_hashes_to_store=[1, 2],
store_block_ids=[0, 1],
block_hashes_evicted=[],
),
)
# complete store [1, 2]
arc_manager.complete_store(to_hashes([1, 2]))
verify_events(
arc_manager.take_events(), block_size=block_size, expected_stores=({1, 2},)
)
# lookup [1, 2] -> not ready
assert cpu_manager.lookup(to_hashes([1, 2])) == 0
# lookup [1, 2]
assert arc_manager.lookup(to_hashes([1])) == 1
assert arc_manager.lookup(to_hashes([1, 2])) == 2
assert arc_manager.lookup(to_hashes([1, 2, 3])) == 2
# no events so far
assert list(cpu_manager.take_events()) == []
# blocks should be in T1 (recent)
assert len(arc_policy.t1) == 2
assert len(arc_policy.t2) == 0
# complete store [1, 2]
cpu_manager.complete_store(to_hashes([1, 2]))
verify_events(
cpu_manager.take_events(), block_size=256, expected_stores=({1, 2},)
)
# lookup [1, 2]
assert cpu_manager.lookup(to_hashes([1])) == 1
assert cpu_manager.lookup(to_hashes([1, 2])) == 2
assert cpu_manager.lookup(to_hashes([1, 2, 3])) == 2
def test_arc_manager_t1_to_t2_promotion():
"""
Tests that accessing a block in T1 promotes it to T2 (frequent).
This is a key feature of ARC's adaptive behavior.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=4, cache_policy="arc", enable_events=False
)
arc_policy = arc_manager._policy
assert isinstance(arc_policy, ARCCachePolicy)
# blocks should be in T1 (recent)
assert len(arc_policy.t1) == 2
assert len(arc_policy.t2) == 0
# store and complete block 1
arc_manager.prepare_store(to_hashes([1]))
arc_manager.complete_store(to_hashes([1]))
def test_t1_to_t2_promotion(self):
"""
Tests that accessing a block in T1 promotes it to T2 (frequent).
This is a key feature of ARC's adaptive behavior.
"""
cpu_manager, arc_policy = self._make_manager(enable_events=False)
# block 1 starts in T1 (recent)
assert to_hashes([1])[0] in arc_policy.t1
assert to_hashes([1])[0] not in arc_policy.t2
# store and complete block 1
cpu_manager.prepare_store(to_hashes([1]))
cpu_manager.complete_store(to_hashes([1]))
# touch block 1 (simulate second access)
arc_manager.touch(to_hashes([1]))
# block 1 starts in T1 (recent)
assert to_hashes([1])[0] in arc_policy.t1
assert to_hashes([1])[0] not in arc_policy.t2
# block 1 should now be in T2 (frequent)
assert to_hashes([1])[0] not in arc_policy.t1
assert to_hashes([1])[0] in arc_policy.t2
# touch block 1 (simulate second access)
cpu_manager.touch(to_hashes([1]))
# block 1 should now be in T2 (frequent)
assert to_hashes([1])[0] not in arc_policy.t1
assert to_hashes([1])[0] in arc_policy.t2
def test_arc_manager_eviction_with_load():
"""
Tests ARC eviction behavior similar to LRU test.
Verifies that blocks being loaded (ref_cnt > 0) cannot be evicted.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=4, cache_policy="arc", enable_events=True
)
def test_eviction_with_load(self):
"""
Tests ARC eviction behavior similar to LRU test.
Verifies that blocks being loaded (ref_cnt > 0) cannot be evicted.
"""
cpu_manager, _ = self._make_manager()
# prepare and complete store [1, 2, 3, 4]
prepare_store_output = arc_manager.prepare_store(to_hashes([1, 2, 3, 4]))
verify_store_output(
prepare_store_output,
ExpectedPrepareStoreOutput(
block_hashes_to_store=[1, 2, 3, 4],
store_block_ids=[0, 1, 2, 3],
block_hashes_evicted=[],
),
)
arc_manager.complete_store(to_hashes([1, 2, 3, 4]))
# prepare and complete store [1, 2, 3, 4]
prepare_store_output = cpu_manager.prepare_store(to_hashes([1, 2, 3, 4]))
verify_store_output(
prepare_store_output,
ExpectedPrepareStoreOutput(
block_hashes_to_store=[1, 2, 3, 4],
store_block_ids=[0, 1, 2, 3],
block_hashes_evicted=[],
),
)
cpu_manager.complete_store(to_hashes([1, 2, 3, 4]))
# prepare load [2, 3] (increases ref_cnt)
prepare_load_output = arc_manager.prepare_load(to_hashes([2, 3]))
verify_load_output(prepare_load_output, [1, 2])
# prepare load [2, 3] (increases ref_cnt)
prepare_load_output = cpu_manager.prepare_load(to_hashes([2, 3]))
verify_load_output(prepare_load_output, [1, 2])
# prepare store [5, 6, 7] with [2, 3] being loaded
# should fail because [2, 3] have ref_cnt > 0
assert arc_manager.prepare_store(to_hashes([5, 6, 7])) is None
# prepare store [5, 6, 7] with [2, 3] being loaded
# should fail because [2, 3] have ref_cnt > 0
assert cpu_manager.prepare_store(to_hashes([5, 6, 7])) is None
# complete load [2, 3]
arc_manager.complete_load(to_hashes([2, 3]))
# complete load [2, 3]
cpu_manager.complete_load(to_hashes([2, 3]))
# now prepare store [5, 6, 7] should succeed
# ARC will evict blocks one at a time from T1 as needed
prepare_store_output = arc_manager.prepare_store(to_hashes([5, 6, 7]))
assert prepare_store_output is not None
# Should successfully evict enough blocks to make room (at least 1)
assert len(prepare_store_output.block_hashes_evicted) >= 1
# now prepare store [5, 6, 7] should succeed
# ARC will evict blocks one at a time from T1 as needed
prepare_store_output = cpu_manager.prepare_store(to_hashes([5, 6, 7]))
assert prepare_store_output is not None
# Should successfully evict enough blocks to make room (at least 1)
assert len(prepare_store_output.block_hashes_evicted) >= 1
def test_adaptive_target(self):
"""
Tests ARC's adaptive target adjustment via ghost lists.
When a block in B1 (ghost list) is accessed, target_t1_size increases.
When a block in B2 is accessed, target_t1_size decreases.
"""
cpu_manager, arc_policy = self._make_manager(num_blocks=2, enable_events=False)
def test_arc_manager_adaptive_target():
"""
Tests ARC's adaptive target adjustment via ghost lists.
When a block in B1 (ghost list) is accessed, target_t1_size increases.
When a block in B2 is accessed, target_t1_size decreases.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=2, cache_policy="arc", enable_events=False
)
arc_policy = arc_manager._policy
assert isinstance(arc_policy, ARCCachePolicy)
# store blocks 1, 2 (fills cache)
cpu_manager.prepare_store(to_hashes([1, 2]))
cpu_manager.complete_store(to_hashes([1, 2]))
# store blocks 1, 2 (fills cache)
arc_manager.prepare_store(to_hashes([1, 2]))
arc_manager.complete_store(to_hashes([1, 2]))
initial_target = arc_policy.target_t1_size
initial_target = arc_policy.target_t1_size
# store block 3, evicting block 1 (moves to B1 ghost list)
cpu_manager.prepare_store(to_hashes([3]))
cpu_manager.complete_store(to_hashes([3]))
# store block 3, evicting block 1 (moves to B1 ghost list)
arc_manager.prepare_store(to_hashes([3]))
arc_manager.complete_store(to_hashes([3]))
# block 1 should be in B1 (ghost list)
assert to_hashes([1])[0] in arc_policy.b1
# block 1 should be in B1 (ghost list)
assert to_hashes([1])[0] in arc_policy.b1
# touch block 1 (cache miss, but in B1)
# this should increase target_t1_size (favor recency)
cpu_manager.touch(to_hashes([1]))
# touch block 1 (cache miss, but in B1)
# this should increase target_t1_size (favor recency)
arc_manager.touch(to_hashes([1]))
# target should have increased
assert arc_policy.target_t1_size > initial_target
# target should have increased
assert arc_policy.target_t1_size > initial_target
def test_t1_t2_eviction_policy(self):
"""
Tests that ARC evicts from T1 or T2 based on target_t1_size.
If |T1| >= target_t1_size, evict from T1, otherwise from T2.
"""
cpu_manager, arc_policy = self._make_manager(enable_events=False)
# store blocks 1, 2, 3, 4
cpu_manager.prepare_store(to_hashes([1, 2, 3, 4]))
cpu_manager.complete_store(to_hashes([1, 2, 3, 4]))
def test_arc_manager_t1_t2_eviction_policy():
"""
Tests that ARC evicts from T1 or T2 based on target_t1_size.
If |T1| >= target_t1_size, evict from T1, otherwise from T2.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=4, cache_policy="arc", enable_events=False
)
arc_policy = arc_manager._policy
assert isinstance(arc_policy, ARCCachePolicy)
# promote blocks 3, 4 to T2 by touching them
cpu_manager.touch(to_hashes([3, 4]))
# store blocks 1, 2, 3, 4
arc_manager.prepare_store(to_hashes([1, 2, 3, 4]))
arc_manager.complete_store(to_hashes([1, 2, 3, 4]))
# now: T1 = {1, 2}, T2 = {3, 4}
assert len(arc_policy.t1) == 2
assert len(arc_policy.t2) == 2
# promote blocks 3, 4 to T2 by touching them
arc_manager.touch(to_hashes([3, 4]))
# set target_t1_size to prefer evicting from T1
# (when |T1| >= target, evict from T1)
arc_policy.target_t1_size = 1
# now: T1 = {1, 2}, T2 = {3, 4}
assert len(arc_policy.t1) == 2
assert len(arc_policy.t2) == 2
# store block 5, should evict from T1 (block 1, LRU in T1)
output = cpu_manager.prepare_store(to_hashes([5]))
assert output is not None
assert to_hashes([1]) == output.block_hashes_evicted
# set target_t1_size to prefer evicting from T1
# (when |T1| >= target, evict from T1)
arc_policy.target_t1_size = 1
cpu_manager.complete_store(to_hashes([5]))
# store block 5, should evict from T1 (block 1, LRU in T1)
output = arc_manager.prepare_store(to_hashes([5]))
assert output is not None
assert to_hashes([1]) == output.block_hashes_evicted
# block 1 should be in B1 (ghost list)
assert to_hashes([1])[0] in arc_policy.b1
# block 5 should be in T1
assert to_hashes([5])[0] in arc_policy.t1
arc_manager.complete_store(to_hashes([5]))
def test_ghost_list_bounds(self):
"""
Tests that ghost lists (B1, B2) don't grow unbounded.
They should be capped at cache_capacity.
"""
cpu_manager, arc_policy = self._make_manager(num_blocks=2, enable_events=False)
# block 1 should be in B1 (ghost list)
assert to_hashes([1])[0] in arc_policy.b1
# block 5 should be in T1
assert to_hashes([5])[0] in arc_policy.t1
# fill cache with blocks 1, 2
cpu_manager.prepare_store(to_hashes([1, 2]))
cpu_manager.complete_store(to_hashes([1, 2]))
# store many blocks to fill ghost lists
for i in range(3, 20):
cpu_manager.prepare_store(to_hashes([i]))
cpu_manager.complete_store(to_hashes([i]))
def test_arc_manager_ghost_list_bounds():
"""
Tests that ghost lists (B1, B2) don't grow unbounded.
They should be capped at cache_capacity.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=2, cache_policy="arc", enable_events=False
)
arc_policy = arc_manager._policy
assert isinstance(arc_policy, ARCCachePolicy)
# ghost lists should not exceed cache_capacity
assert len(arc_policy.b1) <= arc_policy.cache_capacity
assert len(arc_policy.b2) <= arc_policy.cache_capacity
# fill cache with blocks 1, 2
arc_manager.prepare_store(to_hashes([1, 2]))
arc_manager.complete_store(to_hashes([1, 2]))
def test_touch_ordering(self):
"""
Tests that touch() correctly updates access patterns.
Similar to LRU test but verifies T1/T2 ordering.
"""
cpu_manager, arc_policy = self._make_manager()
# store many blocks to fill ghost lists
for i in range(3, 20):
arc_manager.prepare_store(to_hashes([i]))
arc_manager.complete_store(to_hashes([i]))
# store blocks 1, 2, 3, 4
cpu_manager.prepare_store(to_hashes([1, 2, 3, 4]))
cpu_manager.complete_store(to_hashes([1, 2, 3, 4]))
# ghost lists should not exceed cache_capacity
assert len(arc_policy.b1) <= arc_policy.cache_capacity
assert len(arc_policy.b2) <= arc_policy.cache_capacity
# promote 3, 4 to T2
cpu_manager.touch(to_hashes([3, 4]))
# T1 = {1, 2}, T2 = {3, 4}
# touch [1, 3, 4] - should promote 1 to T2, and move 3,4 to end of T2
cpu_manager.touch(to_hashes([1, 3, 4]))
def test_arc_manager_touch_ordering():
"""
Tests that touch() correctly updates access patterns.
Similar to LRU test but verifies T1/T2 ordering.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=4, cache_policy="arc", enable_events=True
)
arc_policy = arc_manager._policy
assert isinstance(arc_policy, ARCCachePolicy)
# T1 = {2}, T2 = {1, 3, 4} (in that order, with 4 most recent)
assert len(arc_policy.t1) == 1
assert len(arc_policy.t2) == 3
# store blocks 1, 2, 3, 4
arc_manager.prepare_store(to_hashes([1, 2, 3, 4]))
arc_manager.complete_store(to_hashes([1, 2, 3, 4]))
# store block 5, should evict from T1 (block 2, only one in T1)
prepare_store_output = cpu_manager.prepare_store(to_hashes([5]))
verify_store_output(
prepare_store_output,
ExpectedPrepareStoreOutput(
block_hashes_to_store=[5],
store_block_ids=[1], # reuses block 2's storage
block_hashes_evicted=[2],
),
)
# promote 3, 4 to T2
arc_manager.touch(to_hashes([3, 4]))
def test_failed_store(self):
"""
Tests that failed store operations clean up correctly.
Similar to LRU test but for ARC.
"""
cpu_manager, arc_policy = self._make_manager()
# T1 = {1, 2}, T2 = {3, 4}
# touch [1, 3, 4] - should promote 1 to T2, and move 3,4 to end of T2
arc_manager.touch(to_hashes([1, 3, 4]))
# store blocks 1, 2, 3, 4
cpu_manager.prepare_store(to_hashes([1, 2, 3, 4]))
cpu_manager.complete_store(to_hashes([1, 2, 3, 4]))
# T1 = {2}, T2 = {1, 3, 4} (in that order, with 4 most recent)
assert len(arc_policy.t1) == 1
assert len(arc_policy.t2) == 3
# prepare store block 5 (will evict block 1)
prepare_store_output = cpu_manager.prepare_store(to_hashes([5]))
assert prepare_store_output is not None
assert len(prepare_store_output.block_hashes_evicted) == 1
# store block 5, should evict from T1 (block 2, only one in T1)
prepare_store_output = arc_manager.prepare_store(to_hashes([5]))
verify_store_output(
prepare_store_output,
ExpectedPrepareStoreOutput(
block_hashes_to_store=[5],
store_block_ids=[1], # reuses block 2's storage
block_hashes_evicted=[2],
),
)
# complete store with failure
cpu_manager.complete_store(to_hashes([5]), success=False)
# block 5 should not be in cache
assert cpu_manager.lookup(to_hashes([5])) == 0
# block 5 should not be in T1 or T2
assert to_hashes([5])[0] not in arc_policy.t1
assert to_hashes([5])[0] not in arc_policy.t2
def test_arc_manager_failed_store():
"""
Tests that failed store operations clean up correctly.
Similar to LRU test but for ARC.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=4, cache_policy="arc", enable_events=True
)
arc_policy = arc_manager._policy
assert isinstance(arc_policy, ARCCachePolicy)
# evicted block should still be gone (in B1 ghost list)
evicted_hash = prepare_store_output.block_hashes_evicted[0]
assert evicted_hash in arc_policy.b1
# store blocks 1, 2, 3, 4
arc_manager.prepare_store(to_hashes([1, 2, 3, 4]))
arc_manager.complete_store(to_hashes([1, 2, 3, 4]))
def test_full_scenario(self):
"""
Comprehensive test covering multiple ARC operations in sequence.
Similar to the full LRU test but adapted for ARC behavior.
"""
cpu_manager, arc_policy = self._make_manager()
# prepare store block 5 (will evict block 1)
prepare_store_output = arc_manager.prepare_store(to_hashes([5]))
assert prepare_store_output is not None
assert len(prepare_store_output.block_hashes_evicted) == 1
# store [1, 2]
cpu_manager.prepare_store(to_hashes([1, 2]))
cpu_manager.complete_store(to_hashes([1, 2]))
# complete store with failure
arc_manager.complete_store(to_hashes([5]), success=False)
# store [3, 4, 5] -> evicts [1]
prepare_store_output = cpu_manager.prepare_store(to_hashes([3, 4, 5]))
assert prepare_store_output is not None
assert len(prepare_store_output.block_hashes_evicted) == 1
cpu_manager.complete_store(to_hashes([3, 4, 5]))
# block 5 should not be in cache
assert arc_manager.lookup(to_hashes([5])) == 0
# block 5 should not be in T1 or T2
assert to_hashes([5])[0] not in arc_policy.t1
assert to_hashes([5])[0] not in arc_policy.t2
# promote some blocks to T2
cpu_manager.touch(to_hashes([2, 3]))
# evicted block should still be gone (in B1 ghost list)
evicted_hash = prepare_store_output.block_hashes_evicted[0]
assert evicted_hash in arc_policy.b1
# T1 has {4, 5}, T2 has {2, 3}
assert len(arc_policy.t1) == 2
assert len(arc_policy.t2) == 2
# store [6] -> should evict from T1 (4 is oldest in T1)
prepare_store_output = cpu_manager.prepare_store(to_hashes([6]))
assert prepare_store_output is not None
cpu_manager.complete_store(to_hashes([6]))
def test_arc_manager_full_scenario():
"""
Comprehensive test covering multiple ARC operations in sequence.
Similar to the full LRU test but adapted for ARC behavior.
"""
block_size = 256
arc_manager = CPUOffloadingManager(
block_size=block_size, num_blocks=4, cache_policy="arc", enable_events=True
)
arc_policy = arc_manager._policy
assert isinstance(arc_policy, ARCCachePolicy)
# verify blocks 2, 3 (in T2) are still present
assert cpu_manager.lookup(to_hashes([2])) == 1
assert cpu_manager.lookup(to_hashes([3])) == 1
# store [1, 2]
arc_manager.prepare_store(to_hashes([1, 2]))
arc_manager.complete_store(to_hashes([1, 2]))
# store [3, 4, 5] -> evicts [1]
prepare_store_output = arc_manager.prepare_store(to_hashes([3, 4, 5]))
assert prepare_store_output is not None
assert len(prepare_store_output.block_hashes_evicted) == 1
arc_manager.complete_store(to_hashes([3, 4, 5]))
# promote some blocks to T2
arc_manager.touch(to_hashes([2, 3]))
# T1 has {4, 5}, T2 has {2, 3}
assert len(arc_policy.t1) == 2
assert len(arc_policy.t2) == 2
# store [6] -> should evict from T1 (4 is oldest in T1)
prepare_store_output = arc_manager.prepare_store(to_hashes([6]))
assert prepare_store_output is not None
arc_manager.complete_store(to_hashes([6]))
# verify blocks 2, 3 (in T2) are still present
assert arc_manager.lookup(to_hashes([2])) == 1
assert arc_manager.lookup(to_hashes([3])) == 1
# verify events
events = list(arc_manager.take_events())
assert len(events) > 0 # should have store and eviction events
# verify events
events = list(cpu_manager.take_events())
assert len(events) > 0 # should have store and eviction events
def test_filter_reused_manager():
@@ -583,8 +549,6 @@ def test_filter_reused_manager():
block_size=block_size, num_blocks=4, cache_policy="lru", enable_events=True
)
from vllm.v1.kv_offload.reuse_manager import FilterReusedOffloadingManager
manager = FilterReusedOffloadingManager(
backing=lru_manager, store_threshold=2, max_tracker_size=3
)