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[None][feat] Support layer and buffer reuse policies for attention and SSM - #21088
KV Cache Manager V2 previously supported reuse policies only for attention layers, with all recurrent state sharing one required lifecycle. Generalize the enum to ReusePolicy, add a layer-level policy for SSM, and allow attention and SSM buffers to override their layer's policy. BufferConfig.reuse_policy=None inherits the layer policy, so existing uniform-layer configurations retain their behavior.
REQUIRED buffers constrain prefix reuse. OPTIONAL state can be selected on first resume at the matched endpoint; unselected groups contribute no lookup, hit or miss counters. PRIVATE state remains request-local and is never published as a reusable checkpoint. Consumers initialize or reconstruct fresh state.
Deduplicate SSM lifecycles by effective policy, with at most three groups. Attention lifecycles retain their window and sink properties in addition to policy. Sparsity remains a per-pool storage property, as on upstream main. Handle snapshots, allocation, beams, eviction and accounting across these groups.
Add get_buffer_group_id(layer_id, role) and buffer_grouping, returning or indexing by the public CacheGroupId alias of LifeCycleId. Keep LayerGroupId and existing layer APIs. The layer APIs preserve uniform-layer behavior, reject ambiguous split layers with TLLM_CHECK_WITH_INFO (RuntimeError in Python), and are deprecated in documentation only, with no runtime warnings.
Replace persistent LayerAttr metadata with BufferAttr.scratchPagesPerBlock and per-lifecycle scratch utilization. Coalesce compatible buffers within their lifecycle. The native page-index converter handles unequal buffer membership and blocks crossing physical scratch slots.
Register lifecycles only for actual buffers; remove the layer-only factory while validating each layer independently of its buffer count.
Existing Python consumers continue using their layer-based APIs. Adoption of split buffers in wrappers, sharing, connectors and disaggregation is deferred. Preserve an SSM layer's existing policy when filtering zero-size buffers.
Rename AttentionReusePolicy to ReusePolicy without a compatibility alias and migrate existing callers. The enum values are unchanged. This does not change high-level LLM API configuration or its stability references.
Independent buffer policies require independent indices in the consumer. Current Mamba kernels share recurrent-state and replay-slot indices; separate indices remain a follow-up, and replay buffers are not made PRIVATE by default. Existing attention scratch-table kernels require whole layer blocks per slot; custom consumers of crossing layouts must use the native converter or implement compatible index generation. Layers configured with the native sparse fetch path also require one group per layer; checked layer lookup rejects split layouts. Kernel changes are outside this PR. OPTIONAL attention reuse retains its block-aligned sliding-window endpoint requirements.
The per-buffer implementation incorporates jiaganc#4.
Test Coverage
Rebased onto upstream main a4e0757a8b97f10a33d544ce020d94edfab8be76 and validated final PR revision d0911a1c9fcd967db113ae87e6dad68a35343eaf on shared B200-01 (umbriel-b200-027). Pre-commit checks, the clean build after rebase, and the incremental rebuild for the final fix passed.
All 13 KVCM V2 C++ suites: 154 passed, 0 failures/errors with TLLM_DEBUG_MODE=1.
Skips: 12 disabled performance cases and two NUMA-placement cases because every GPU exposes NUMA node 0.
The complete validation script exited successfully at the final PR head.
The run covers the full Python KVCM V2 suite, including upstream sparse-cache coverage, plus wrapper, Mamba, Helix, CSA2, staging/sharing, connector, disaggregation, cache estimation, mixed-precision and DeepSeek snapshot suites. Python tests use TLLM_DEBUG_MODE=0 because debug mode hits an existing V1 KVCacheIndex{INT32_MAX} sentinel assertion in unchanged code.
Direct API regression coverage includes policy inheritance, uniform and ambiguous group lookup, attention and SSM optional selection, unselected-state statistics, private snapshots/beams/offload, and scratch address separation. Added coverage for uniform buffer policy overrides in the sparse fetch path and rejection of split layers there.
The rebased C++ run exposed an invariant that required SSM working state to remain locked even after suspension. The final fix checks for a lock while active and a page holder while suspended; existing policy tests now also close suspended readers. All affected tests passed after the fix.
PR Checklist
Description explains the behavior, rationale and consumer limitations.
Changes follow coding guidelines; commits have DCO sign-off and pass pre-commit hooks.
Behavioral regression tests cover the new paths.
Configuration documentation and public stubs are updated.
No high-level LLM API, dependency or ownership changes.
No architecture diagram update is needed.
Final affected-test results verified for the latest rebased revision.
Dev Engineer Review
The change generalizes reuse policies across attention and SSM buffers. Buffers inherit their layer policy unless they define an override. Lifecycle registration, storage metadata, page-index conversion, and SSM state management now support multiple lifecycles per layer.
The new buffer-group APIs support split-policy layers. Legacy layer-group lookups reject ambiguous split-layer queries. The public AttentionReusePolicy name is replaced by ReusePolicy; no compatibility alias is described in the supplied change summary. Downstream users of the old name may need updates.
The supplied objectives defer independent recurrent-state and replay-slot indices and consumer adoption of split buffers. Sparse-fetch and attention scratch-table consumers require uniform layouts. Optional attention reuse retains block-aligned sliding-window endpoint requirements. These constraints warrant follow-up as consumers adopt split buffers.
No current review findings were supplied, so review-finding counts are unavailable. Validation for the latest rebased revision was still pending for clean-build and affected tests. The author reported earlier results of 201 passing C++ tests and 2,229 passing Python tests, 14 skips, and 92 passing subtests; these results do not validate the latest revision. CI reports include an UNSTABLE pipeline and a later failed run. The supplied information does not establish the outcome of the latest validation.
QA Engineer Review
Changed C++ and Python tests cover policy overrides, split lifecycle grouping, SSM reuse and restoration, page-index conversion, scratch-address separation, zero-size buffer filtering, and reservation readiness. The supplied results do not establish test outcomes for the latest revision.
The changed test files are listed below. The inspected CI lists contain existing entries for two tests in test_cache_manager.py and a file-level entry for test_mixed_precision_kv_cache.py. test_kvcm2_integration.py has a list entry for test_helix_retention_uses_rank_local_ranges, not its new zero-size-buffer policy test. No matching entries were found for the other changed test files, and no matching manual-QA entries were found.
Coverage verdict: needs follow-up. Confirm that CI runs the new tests, especially the tests for split policies and unequal buffer membership.
Per-File QA Perspective
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/AGENTS.md — Documents policy inheritance, lifecycle grouping, and split-layer behavior. Check that the guidance matches runtime behavior.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/blockRadixTree.cpp — Uses required SSM lifecycle selection during matching and pruning. Verify prefix pruning when SSM lifecycles use different policies.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/config.h — Adds shared ReusePolicy, buffer overrides, and SSM layer defaults. Verify defaults and compatibility with users of the removed enum name.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp — Extends allocation, snapshots, cleanup, and reuse handling to multiple SSM lifecycles. Verify optional selection, private-state isolation, and offload restoration.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.h — Changes the reuse-policy type and adds a lookup-token counter. Verify status reporting and counter behavior.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.cpp — Adds buffer-group lookup and rejects ambiguous layer-group queries. Verify group membership, ordering, and split-layer errors.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.h — Exposes buffer grouping and lookup, and deprecates layer-group APIs. Verify that the declarations match the Python bindings.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/lifeCycleRegistry.cpp — Registers buffers using effective policies. Verify lifecycle deduplication across buffers and layers.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/lifeCycleRegistry.h — Adds policy-aware SSM lifecycles and multi-lifecycle accessors. Verify required-lifecycle selection and equality behavior.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/page.cpp — Identifies SSM pages through the registry. Verify page checks for every SSM lifecycle ID.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storage/config.cpp — Maps layers to multiple lifecycle IDs and builds storage from layer-buffer pairs. Verify split-buffer metadata and lifecycle mapping.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storage/config.h — Adds scratch-page metadata and changes layer-to-lifecycle results to vectors. Verify that consumers handle multiple IDs.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.cpp — Updates scratch sizing and pool grouping. Verify sizing when buffers have different group membership or policies.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.h — Changes the lifecycle mapping API and removes layer attributes. Verify that callers do not assume one lifecycle per layer.
cpp/tensorrt_llm/nanobind/batch_manager/kvCacheManagerV2.cpp — Exposes the shared enum, policy configuration, and buffer-group APIs to Python. Verify defaults and the multiple-SSM error path.
cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ColdPageTest.cpp — Updates policy naming and waits for reservation readiness before poisoning slots. Verify the test respects slot readiness. This file is outside the requested tests/ test-list check.
cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ConfigTest.cpp — Adds attention override and SSM grouping coverage. Verify policy deduplication and group ordering. This file is outside the requested tests/ test-list check.
cpp/tests/unit_tests/batch_manager/kvCacheManagerV2StatsTest.cpp — Adds SSM reuse, offload, beam expansion, and split-buffer coverage. Verify snapshot accounting and address mappings. This file is outside the requested tests/ test-list check.
tensorrt_llm/_torch/attention/backends/sparse/csa2/cache_manager.py — Replaces the enum used for encoder reuse configuration. Verify policy selection remains unchanged.
tensorrt_llm/_torch/pyexecutor/kv_cache/kv_cache_manager_v2.py — Updates policy annotations and preserves SSM policy when filtering buffers. Verify SSM and mixed-precision layer configuration.
tensorrt_llm/runtime/kv_cache_manager_v2/__init__.py — Re-exports ReusePolicy instead of the old enum. Verify downstream imports.
tensorrt_llm/runtime/kv_cache_manager_v2/__init__.pyi — Updates public policy, buffer, and grouping declarations. Verify that the stubs match runtime bindings.
tests/unittest/_torch/attention/sparse/csa2/test_cache_manager.py — Updates decoder replay policy assertions. The CI lists contain two other tests from this file, not the changed test.
tests/unittest/_torch/executor/kv_cache/test_kv_cache_estimation.py — Updates the enum used in sizing assertions. No matching CI or manual-QA entry was found.
tests/unittest/_torch/executor/kv_cache/test_kvcm2_integration.py — Adds zero-size buffer filtering coverage, including policy preservation. Its CI entry names a different test.
tests/unittest/_torch/executor/kv_cache/test_mixed_precision_kv_cache.py — Updates required-policy assertions. The file has a CI list entry.
tests/unittest/_torch/modeling/test_deepseek_v41_snapshots.py — Updates snapshot policy assertions. No matching CI or manual-QA entry was found.
tests/unittest/kv_cache_manager_v2_tests/test_kv_cache_concurrency.py — Updates optional-policy setup in concurrency tests. No matching CI or manual-QA entry was found.
tests/unittest/kv_cache_manager_v2_tests/test_optional_checkpoint.py — Adds tests for sparse-fetch policy behavior, optional selection, split layers, and scratch-address separation. No matching CI or manual-QA entry was found.
jiaganc
changed the title
[None][feat] BREAKING: Support layer-level reuse policies for attention and SSM
[None][feat] Support layer-level reuse policies for attention and SSM
Oct 27, 2026
jiaganc
changed the title
[None][feat] Support layer-level reuse policies for attention and SSM
[None][feat] Support layer and buffer reuse policies for attention and SSM
Oct 28, 2026
filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, SoftFileLock versions from 4.1.0 can reuse a stale observation when an attacker pre-dates and removes its own marker, at least two lock-user processes are waiting, coarse or matching modification times preserve the observation, and an honest contender creates a fresh marker on the reused inode, causing that live marker to be removed as stale. This issue is fixed in version 4.2.1.
filelock is a platform-independent file lock for Python. From 3.20.4 until 4.2.1, ReadWriteLock let SQLite reopen the database and side files by name; on POSIX systems an attacker with rename access in a non-sticky parent can swap those names to cause overwrite or unlink operations, while a writable adjacent hot journal is additionally required for attacker-chosen content overwrites. This issue is fixed in version 4.2.1.
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The KV cache manager adds shared reuse policies and per-buffer overrides for attention and SSM state. It supports multiple SSM lifecycles and adds buffer-level grouping and page-index APIs. Python bindings and runtime code expose the updated configuration and interfaces.
Changes
Per-buffer reuse policies and lifecycle registration
Layer / File(s)
Summary
Policy and lifecycle registration cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/config.h, lifeCycleRegistry.*, storage/config.*, storageManager.*, cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ConfigTest.cpp, cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/AGENTS.md
A shared ReusePolicy applies to attention and SSM lifecycles. Buffer policies can override layer defaults. Lifecycle registration processes each buffer, and a layer can map to multiple lifecycle IDs. Storage attributes and sizing use per-buffer and per-lifecycle data.
Cache operations now handle multiple SSM lifecycle groups across resume, allocation, snapshots, commit, beam expansion, cleanup, and validation. Optional SSM state can be reused only at an exact endpoint. Tests cover policy groups, snapshot reuse, allocation, and restoration.
Storage groups and page conversion
Layer / File(s)
Summary
Buffer grouping and scratch-page conversion cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.*, cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storage/config.*, cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ColdPageTest.cpp, cpp/tests/unit_tests/batch_manager/kvCacheManagerV2StatsTest.cpp, tests/unittest/kv_cache_manager_v2_tests/test_optional_checkpoint.py
The manager adds buffer-level lifecycle-group queries and grouping. Layer-level queries throw when a layer spans groups. Page-index conversion uses each buffer’s scratch-page count. Tests check grouping, address ranges, and cold-page slot reservations.
Python bindings and type declarations expose ReusePolicy, buffer overrides, SSM layer policies, and buffer grouping. Runtime code and tests use the renamed enum. Filtering zero-sized buffers preserves configured policies.
The changes to SSM reuse policies and per-buffer lifecycle handling show no remaining concrete defects after review. Merge readiness depends on the author's pending clean-build and affected-test results and on resolving the CI failure.
Pre-merge checks: 4 · 1
Failed checks: 1 warning
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Passed checks: 4 passed
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The title names the main change: adding layer and buffer reuse policies for attention and SSM in KV Cache Manager V2. It follows the repository template with the [None][feat] prefix. The title is accu…
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The title names the main change: adding layer and buffer reuse policies for attention and SSM in KV Cache Manager V2. It follows the repository template with the [None][feat] prefix. The title is accurate and specific, and it is 74 characters long, which is acceptable.
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The existing test uses scratchPagesPerBlock = 2 with scale = 6, so crossesSlots is false. It also calls the converter without a ScratchDesc. Add a case with scale = 3, scratchPagesPerBlock = 2, a non-null ScratchDesc spanning at least two scratch blocks, and assertions for distinct role indices across the slot boundary.
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Review comment at
@cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.cpp at line
76:
Extend the converter test covering the crossesSlots calculation with a case
using scale 3 and scratchPagesPerBlock 2, passing a non-null ScratchDesc that
spans at least two scratch blocks; assert that role indices are distinct across
the slot boundary.
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Inline comments:
Review comments at @tensorrt_llm/runtime/kv_cache_manager_v2/__init__.pyi:
- Around line 269-272: Update the BufferConfig.reuse_policy documentation to
state that both attention and SSM buffers can override the layer’s policy.
Describe the buffer as belonging to the layer group for the selected policy
while retaining its layer ID, without restricting overrides to SSM layers.
---
Nitpick comments:
Review comments at
@cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.cpp:
- Line 76: Extend the converter test covering the crossesSlots calculation with
a case using scale 3 and scratchPagesPerBlock 2, passing a non-null ScratchDesc
that spans at least two scratch blocks; assert that role indices are distinct
across the slot boundary.
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Add an optional per-buffer reuse policy. A BufferConfig without one uses
its layer's policy. An SSM buffer may set a different policy and then
belongs to the SSM lifecycle of that policy while keeping its layer ID,
so one SSM layer can span several layer groups. Attention buffers must
use their layer's policy.
Lifecycle registration and the storage layout are built per buffer, and
per-layer storage attributes are keyed by (layer, lifecycle), so page
index converters use the buffer's own lifecycle.
Add getLayerGroupId(layerId, role) and its get_layer_group_id(layer_id,
role) binding. The one-argument overload throws when a layer's buffers
span several groups; layerGrouping lists such a layer under each group.
Signed-off-by: Xiwen Yu <13230610+VALLIS-NERIA@users.noreply.github.com>
…By Agent)
_remove_zero_size_buffers rebuilt SSM layer configs without their reuse
policy, which turned PRIVATE and OPTIONAL SSM layers into REQUIRED ones
whenever any layer had a zero-size buffer. Forward the layer policy; the
retained buffers keep their own policies.
Describe how the layer-group helpers handle an SSM layer listed under
several groups and cover them with a split layer.
Signed-off-by: Xiwen Yu <13230610+VALLIS-NERIA@users.noreply.github.com>
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Description
KV Cache Manager V2 previously supported reuse policies only for attention layers, with all recurrent state sharing one required lifecycle. Generalize the enum to
ReusePolicy, add a layer-level policy for SSM, and allow attention and SSM buffers to override their layer's policy.BufferConfig.reuse_policy=Noneinherits the layer policy, so existing uniform-layer configurations retain their behavior.get_buffer_group_id(layer_id, role)andbuffer_grouping, returning or indexing by the publicCacheGroupIdalias ofLifeCycleId. KeepLayerGroupIdand existing layer APIs. The layer APIs preserve uniform-layer behavior, reject ambiguous split layers withTLLM_CHECK_WITH_INFO(RuntimeErrorin Python), and are deprecated in documentation only, with no runtime warnings.LayerAttrmetadata withBufferAttr.scratchPagesPerBlockand per-lifecycle scratch utilization. Coalesce compatible buffers within their lifecycle. The native page-index converter handles unequal buffer membership and blocks crossing physical scratch slots.Rename
AttentionReusePolicytoReusePolicywithout a compatibility alias and migrate existing callers. The enum values are unchanged. This does not change high-level LLM API configuration or its stability references.Independent buffer policies require independent indices in the consumer. Current Mamba kernels share recurrent-state and replay-slot indices; separate indices remain a follow-up, and replay buffers are not made PRIVATE by default. Existing attention scratch-table kernels require whole layer blocks per slot; custom consumers of crossing layouts must use the native converter or implement compatible index generation. Layers configured with the native sparse fetch path also require one group per layer; checked layer lookup rejects split layouts. Kernel changes are outside this PR. OPTIONAL attention reuse retains its block-aligned sliding-window endpoint requirements.
The per-buffer implementation incorporates jiaganc#4.
Test Coverage
Rebased onto upstream main
a4e0757a8b97f10a33d544ce020d94edfab8be76and validated final PR revisiond0911a1c9fcd967db113ae87e6dad68a35343eafon shared B200-01 (umbriel-b200-027). Pre-commit checks, the clean build after rebase, and the incremental rebuild for the final fix passed.TLLM_DEBUG_MODE=1.The run covers the full Python KVCM V2 suite, including upstream sparse-cache coverage, plus wrapper, Mamba, Helix, CSA2, staging/sharing, connector, disaggregation, cache estimation, mixed-precision and DeepSeek snapshot suites. Python tests use
TLLM_DEBUG_MODE=0because debug mode hits an existing V1KVCacheIndex{INT32_MAX}sentinel assertion in unchanged code.Direct API regression coverage includes policy inheritance, uniform and ambiguous group lookup, attention and SSM optional selection, unselected-state statistics, private snapshots/beams/offload, and scratch address separation. Added coverage for uniform buffer policy overrides in the sparse fetch path and rejection of split layers there.
The rebased C++ run exposed an invariant that required SSM working state to remain locked even after suspension. The final fix checks for a lock while active and a page holder while suspended; existing policy tests now also close suspended readers. All affected tests passed after the fix.
PR Checklist
Dev Engineer Review
The change generalizes reuse policies across attention and SSM buffers. Buffers inherit their layer policy unless they define an override. Lifecycle registration, storage metadata, page-index conversion, and SSM state management now support multiple lifecycles per layer.
The new buffer-group APIs support split-policy layers. Legacy layer-group lookups reject ambiguous split-layer queries. The public
AttentionReusePolicyname is replaced byReusePolicy; no compatibility alias is described in the supplied change summary. Downstream users of the old name may need updates.The supplied objectives defer independent recurrent-state and replay-slot indices and consumer adoption of split buffers. Sparse-fetch and attention scratch-table consumers require uniform layouts. Optional attention reuse retains block-aligned sliding-window endpoint requirements. These constraints warrant follow-up as consumers adopt split buffers.
No current review findings were supplied, so review-finding counts are unavailable. Validation for the latest rebased revision was still pending for clean-build and affected tests. The author reported earlier results of 201 passing C++ tests and 2,229 passing Python tests, 14 skips, and 92 passing subtests; these results do not validate the latest revision. CI reports include an
UNSTABLEpipeline and a later failed run. The supplied information does not establish the outcome of the latest validation.QA Engineer Review
Changed C++ and Python tests cover policy overrides, split lifecycle grouping, SSM reuse and restoration, page-index conversion, scratch-address separation, zero-size buffer filtering, and reservation readiness. The supplied results do not establish test outcomes for the latest revision.
The changed test files are listed below. The inspected CI lists contain existing entries for two tests in
test_cache_manager.pyand a file-level entry fortest_mixed_precision_kv_cache.py.test_kvcm2_integration.pyhas a list entry fortest_helix_retention_uses_rank_local_ranges, not its new zero-size-buffer policy test. No matching entries were found for the other changed test files, and no matching manual-QA entries were found.Coverage verdict: needs follow-up. Confirm that CI runs the new tests, especially the tests for split policies and unequal buffer membership.
Per-File QA Perspective
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/AGENTS.md— Documents policy inheritance, lifecycle grouping, and split-layer behavior. Check that the guidance matches runtime behavior.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/blockRadixTree.cpp— Uses required SSM lifecycle selection during matching and pruning. Verify prefix pruning when SSM lifecycles use different policies.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/config.h— Adds sharedReusePolicy, buffer overrides, and SSM layer defaults. Verify defaults and compatibility with users of the removed enum name.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp— Extends allocation, snapshots, cleanup, and reuse handling to multiple SSM lifecycles. Verify optional selection, private-state isolation, and offload restoration.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.h— Changes the reuse-policy type and adds a lookup-token counter. Verify status reporting and counter behavior.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.cpp— Adds buffer-group lookup and rejects ambiguous layer-group queries. Verify group membership, ordering, and split-layer errors.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.h— Exposes buffer grouping and lookup, and deprecates layer-group APIs. Verify that the declarations match the Python bindings.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/lifeCycleRegistry.cpp— Registers buffers using effective policies. Verify lifecycle deduplication across buffers and layers.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/lifeCycleRegistry.h— Adds policy-aware SSM lifecycles and multi-lifecycle accessors. Verify required-lifecycle selection and equality behavior.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/page.cpp— Identifies SSM pages through the registry. Verify page checks for every SSM lifecycle ID.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storage/config.cpp— Maps layers to multiple lifecycle IDs and builds storage from layer-buffer pairs. Verify split-buffer metadata and lifecycle mapping.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storage/config.h— Adds scratch-page metadata and changes layer-to-lifecycle results to vectors. Verify that consumers handle multiple IDs.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.cpp— Updates scratch sizing and pool grouping. Verify sizing when buffers have different group membership or policies.cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.h— Changes the lifecycle mapping API and removes layer attributes. Verify that callers do not assume one lifecycle per layer.cpp/tensorrt_llm/nanobind/batch_manager/kvCacheManagerV2.cpp— Exposes the shared enum, policy configuration, and buffer-group APIs to Python. Verify defaults and the multiple-SSM error path.cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ColdPageTest.cpp— Updates policy naming and waits for reservation readiness before poisoning slots. Verify the test respects slot readiness. This file is outside the requestedtests/test-list check.cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ConfigTest.cpp— Adds attention override and SSM grouping coverage. Verify policy deduplication and group ordering. This file is outside the requestedtests/test-list check.cpp/tests/unit_tests/batch_manager/kvCacheManagerV2StatsTest.cpp— Adds SSM reuse, offload, beam expansion, and split-buffer coverage. Verify snapshot accounting and address mappings. This file is outside the requestedtests/test-list check.tensorrt_llm/_torch/attention/backends/sparse/csa2/cache_manager.py— Replaces the enum used for encoder reuse configuration. Verify policy selection remains unchanged.tensorrt_llm/_torch/pyexecutor/kv_cache/kv_cache_manager_v2.py— Updates policy annotations and preserves SSM policy when filtering buffers. Verify SSM and mixed-precision layer configuration.tensorrt_llm/runtime/kv_cache_manager_v2/__init__.py— Re-exportsReusePolicyinstead of the old enum. Verify downstream imports.tensorrt_llm/runtime/kv_cache_manager_v2/__init__.pyi— Updates public policy, buffer, and grouping declarations. Verify that the stubs match runtime bindings.tests/unittest/_torch/attention/sparse/csa2/test_cache_manager.py— Updates decoder replay policy assertions. The CI lists contain two other tests from this file, not the changed test.tests/unittest/_torch/executor/kv_cache/test_kv_cache_estimation.py— Updates the enum used in sizing assertions. No matching CI or manual-QA entry was found.tests/unittest/_torch/executor/kv_cache/test_kvcm2_integration.py— Adds zero-size buffer filtering coverage, including policy preservation. Its CI entry names a different test.tests/unittest/_torch/executor/kv_cache/test_mixed_precision_kv_cache.py— Updates required-policy assertions. The file has a CI list entry.tests/unittest/_torch/modeling/test_deepseek_v41_snapshots.py— Updates snapshot policy assertions. No matching CI or manual-QA entry was found.tests/unittest/kv_cache_manager_v2_tests/test_kv_cache_concurrency.py— Updates optional-policy setup in concurrency tests. No matching CI or manual-QA entry was found.tests/unittest/kv_cache_manager_v2_tests/test_optional_checkpoint.py— Adds tests for sparse-fetch policy behavior, optional selection, split layers, and scratch-address separation. No matching CI or manual-QA entry was found.