[TRTLLM-16282][feat] Add sparse KV offload and GPU metadata publication by cascade812 · Pull Request #19821 · NVIDIA/TensorRT-LLM

cascade812 · 2026-10-02T21:14:32Z

Description

This PR offloads eligible complete sparse-history KV pages to level-1 host memory during decode and publishes their raw page indices and contiguous host-eligible history counts in stable GPU tables. Pages shared with an owner that still requires GPU storage stay on GPU while decode admission succeeds; native retries offload them when all owners permit it. Host memory becomes authoritative after offload, and completion fences protect reuse of released GPU slots.

The roadmap's runtime path is 4 → owner check → 3 → 5. Blue marks implemented components: steps 1–2 were added in #19580, while steps 3–5, shared-page deferral, and persistent Batch metadata are implemented here. Gray marks existing cache management; white marks future reservation, fetch, and attention work. Step 6 validates the implemented path.

This PR implements steps 3–5 of above implementation plan:

Step 3 — Batched demotion and source release. Deduplicate shared pages, reserve host destinations before copying full coalesced pages, preserve every owner's locks and indices, and release source GPU capacity with the required readiness dependencies. Allocation and codec failures preserve valid source state for retry.
Step 4 — Decode-phase offload and shared-page deferral. Add explicit decode entry and resume handling through generation admission. Offload complete sparse history only when it belongs to every live owner's complete decode history. Otherwise retain the GPU page, locks, and indices, allow decode entry, and record pending work. Retry at decode entry, history updates, and Batch.publish(), including when the watermark is unchanged after another owner enters decode, suspends, or closes. Prefill, partial, input-token, and dense pages retain their required GPU storage.
Step 5 — CPU metadata and GPU publication. Add versioned PageStorageSnapshot metadata and native Batch membership with stable request rows. Retry deferred offloads before collecting dirty rows, then publish final raw page tables and eligible-history counts after KV-copy completion and prior readers. The scalar num_blocks exposes only the contiguous complete history already on host, stopping at the first deferred GPU page or missing mapping; logical history can therefore exceed host eligibility. Expose device arrays through DLPack and integrate publication with executor preparation, connector acceptance, and request teardown.

KvCache marks affected rows dirty when storage, readiness, phase, or eligibility changes; Batch uploads the final state after updates or rollback. Publication transfers metadata. The KV payload stays in its storage pool, with the host copy authoritative after demotion.

Shared-page promotion for prefill/decode coexistence. When prefill reuses a host-locked sparse prefix, restore the same shared page into one GPU allocation after waiting for all readers. Promotion updates every owner's page indices and readiness metadata, then releases the host slot with a completion fence. Decoding owners are marked for offload retry. A prefill owner keeps the GPU page; Batch.publish() retries offload after that owner enters decode, suspends, or closes, even if the decoding owners' history lengths are unchanged. Allocation or copy failures preserve host ownership. This supports aggregated prefill/decode coexistence; sparse KV offload primarily targets disaggregated serving with separate prefill and decode workers.

Current boundary: GPU cache reservation, CPU-to-GPU sparse fetch/refill, selection processing, and attention integration remain follow-up work, as shown in the white portion of the roadmap. The executor rejects offloaded host indices in the dense-attention offset path. Batch currently supports beam width 1.

Test Coverage

Native KvCacheManagerV2SparseOffloadTest, KvCacheManagerV2DecodeOffloadTest, KvCacheManagerV2PageStorageTest, and KvCacheManagerV2BatchTest in kvCacheManagerV2ColdPageTest.cpp.
Shared-page regressions cover multiple blocking owners, decode/resume admission, owner release, retries without history growth, host OOM and codec failures, CUDA reader ordering, and closing the decoder before other owners. Publication tests verify that eligibility grows when a deferred gap closes while row addresses and history length remain stable.
Runtime sparse-configuration, snapshot, publication/DLPack, statistics, and codec regressions in test_kv_cache_manager_v2.py, including three owner-transition cases: decode, suspend, and close.
Generation-admission and metadata-publication cases in test_kv_cache_v2_scheduler.py.

Recorded validation for shared-page deferral on B200, October 2, verified against saved logs/XML in cpp/build/deferred-offload/:

Validation	Result
Native suites linked against the rebuilt production library, debug checks enabled	140 passed, including 63 cold-page/offload/lifecycle/publication cases
Runtime regressions with rebuilt isolated bindings	91 passed, 12 performance cases skipped
Rebuilt production package import and focused runtime checks	Import succeeded; 9 tests passed
Production scheduler/statistics/event suites with debug checks enabled	346 passed; 3 V1 comparison cases failed
Those three V1/V2 comparisons with normal runtime settings	3 passed

The three debug-only failures occur in the unchanged V1 WindowBlockManager dummy-root construction: KVCacheIndex{INT32_MAX} hits its sentinel assertion before the comparison assertions. They remain a separate V1 follow-up. The offload/publication suites pass with debug checks enabled. Isolated bindings also emit the previously reproduced CachedCudaEvent.NULL shutdown warning.

Checks during this PR update: committed-diff whitespace checks and Python syntax parsing passed, as did the pre-push update and confidentiality hooks. GPU suites were not rerun during this update.

PR Checklist

Description and roadmap explain behavior, dependencies, and current limitations.
Tests cover offload, admission, shared-page deferral, metadata, and lifecycle paths.
All four commits include DCO sign-off.
Subsystem guidance and runtime type declarations are updated.
Review CI results and remaining submission requirements.

Dev Engineer Review

The change adds sparse-history page demotion to host memory, shared-owner deferral, versioned page-storage snapshots, and Batch-managed GPU metadata publication. It adds Python bindings and integrates publication with executor preparation, connector reporting, and cache teardown.

Decode entry, history updates, and Batch.publish() retry eligible offloads. Dense-offset copying rejects sparse pages stored on the host. GPU reservation, host-to-GPU fetch, selection, and attention integration remain outside this change. Batch supports beam width 1.

Shared-page ownership, migration completion, prior readers, and stable metadata rows are key correctness areas. The supplied results report three debug-only V1 comparison failures. The author attributes them to an unchanged WindowBlockManager sentinel assertion; the comparisons passed with normal runtime settings. GPU suites were not rerun during the PR update.

QA Engineer Review

The change modifies four test files: two Python unit-test files, an executor integration test file, and a C++ concurrency test. Coverage includes decode admission, resume restoration, metadata publication ordering and failure, dense-offset rejection, slot-release ordering, shared-prefill offload deferral, page-storage lifecycle snapshots, snapshot blocking during a shared API read, and mock cache setup.

Existing CI selectors reference test_kv_cache_v2_scheduler.py in l0_b200.yml and l0_dgx_b200.yml. They cover other named cases; the available results do not show that the new tests are listed. No matching test-list entry was found for test_kv_cache_manager_v2.py. The list status for the C++ concurrency test and the integration test was not established. No test-list files changed.

The supplied results report 140 native cases passed, 91 runtime regression cases passed with 12 performance cases skipped, 9 focused rebuilt-package checks passed, and 346 production scheduler, statistics, and event cases passed. Three debug-only V1 comparison cases failed. GPU suites were not rerun during the PR update. Coverage verdict: needs follow-up, because of the reported debug-only failures and the lack of a GPU-suite rerun during the update.

Per-File QA Perspective

cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/AGENTS.md: Documents Batch ownership, row invalidation, publication, and synchronization. Verify that these requirements match runtime behavior.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/CMakeLists.txt: Adds batch.cpp to the V2 source list. Verify that builds include the implementation.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/batch.cpp: Implements stable request rows, metadata publication, and reader/readiness synchronization. Verify publication, rollback, close, and destruction paths.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/batch.h: Adds the public Batch API. Verify its behavior and beam-width-1 limit.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp: Adds decode-phase tracking, sparse offload, deferred retries, and versioned storage snapshots. Verify admission rollback, resize, resume, and history-update transitions.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.h: Adds PageStorageSnapshot and page-storage/offload APIs. resume now accepts isDecoding. Verify that C++ callers match the updated signature.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.cpp: Adds sparse-lifecycle detection. Verify sparse and unknown-buffer behavior.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.h: Declares isSparse. Verify consistency with the implementation and bindings.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/lifeCycleRegistry.h: Prevents sparse lifecycles from marking sliding-window blocks stale. Verify that sparse history remains available as intended.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/page.cpp: Adds owner tracking and sparse-offload lock handling. Verify owner registration, failure rollback, and unlock ordering.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/page.h: Adds LockOwner and offload-related lock APIs. Verify owner identity for shared-page cases.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.cpp: Adds batched GPU-to-host sparse-page migration. Verify allocation failure, partial submission, completion ordering, and slot release.
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.h: Adds sparse-page migration APIs. Verify caller locking and GPU ownership on failure.
cpp/tensorrt_llm/nanobind/batch_manager/kvCacheManagerV2.cpp: Exposes Batch, BatchDeviceArray, PageStorageSnapshot, and new cache APIs to Python. Verify DLPack stream, device, copy, and dirty-metadata checks.
tensorrt_llm/_torch/pyexecutor/kv_cache/kv_cache_manager_v2.py: Integrates metadata publication and rejects host indices in dense-offset copying. Verify preparation, connector acceptance, generation admission, and teardown ordering.
tensorrt_llm/runtime/kv_cache_manager_v2/__init__.py: Re-exports the new runtime types. Verify that exports match the compiled bindings.
tensorrt_llm/runtime/kv_cache_manager_v2/__init__.pyi: Adds Python type declarations and updates resume. Verify that the stubs match runtime signatures and properties.
tests/unittest/_torch/executor/kv_cache/test_kv_cache_v2_scheduler.py: Adds tests for decode admission, resume restoration, publication ordering and failure, dense-offset rejection, and slot-release ordering. The file has existing CI selectors, but the available results do not confirm that these new tests are listed.
tests/unittest/kv_cache_manager_v2_tests/test_kv_cache_manager_v2.py: Adds tests for GPU metadata publication, shared-prefill deferral, and page-storage lifecycle snapshots. No matching test-list entry was found.
cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ConcurrencyTest.cpp: Adds coverage for snapshot readiness while a shared API reader holds the manager lock. Test-list status was not established.
tests/unittest/_torch/executor/kv_cache/test_kvcm2_integration.py: Updates mocked cache setup with a key-buffer ID and is_sparse=False. Verify that integration behavior remains consistent with the sparse-layer query.

Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

Allow decode admission while shared prefill owners still require GPU pages. Retry deferred offloads at decode, history-update, and Batch publication boundaries, and publish only the contiguous host-eligible history count. Cover owner transitions, unchanged-history retries, transfer failures, and CUDA ordering. Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

cascade812 · 2026-10-03T18:08:40Z

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Walkthrough

This change adds sparse-page migration during KV-cache decode and stable device metadata publication for cache batches. It adds versioned page-storage snapshots, exposes batch and snapshot APIs to Python, integrates publication and residency checks into executor paths, and adds related tests and documentation.

Changes

Sparse Decode and Batch Metadata

Layer / File(s)	Summary
Cache phase and page-storage contract `cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.`, `kvCacheManager.`, `lifeCycleRegistry.h`, `tensorrt_llm/runtime/kv_cache_manager_v2/__init__.pyi`	Adds decode-state and sparse-buffer queries, versioned page-storage snapshots, row binding, dirty tracking, and read synchronization.
Sparse-page migration and cache transitions `cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.`, `page.`, `storageManager.*`	Tracks page-lock owners and migrates eligible sparse pages between GPU and host history. Decode, resume, resize, history updates, and rebase paths handle deferred offloads and rollback.
Stable batch metadata publication `cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/batch.*`, `CMakeLists.txt`	Adds fixed-address page tables and block counts, dirty-row publication, reader synchronization, and batch membership management. The build includes the new implementation.
Python and executor integration `cpp/tensorrt_llm/nanobind/batch_manager/kvCacheManagerV2.cpp`, `tensorrt_llm/runtime/kv_cache_manager_v2/*`, `tensorrt_llm/_torch/pyexecutor/kv_cache/kv_cache_manager_v2.py`, `tests/unittest/...`, `cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/AGENTS.md`	Exposes batch and snapshot APIs, connects metadata publication and residency checks to executor operations, and adds tests and guide updates for decode and publication behavior.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~60 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant Executor
  participant Batch
  participant KvCache
  participant StorageManager
  participant CUDADevice
  Executor->>Batch: Publish on execution stream
  Batch->>KvCache: Retry deferred offload and obtain snapshot
  KvCache->>StorageManager: Offload eligible sparse pages
  StorageManager-->>KvCache: Update page slots and owner indices
  KvCache-->>Batch: Return page-storage snapshot
  Batch->>CUDADevice: Upload dirty row metadata

Suggested reviewers: juney-nvidia, brnguyen2

Merge Risk: 🔵 Low · up to 93edc

The snapshot locking behavior is intact, but its new regression test can pass without proving lock contention. This is a bounded test-confidence gap rather than a demonstrated runtime failure.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 23.53% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 170 functions across 19 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title follows the repository’s ticket-and-type format and clearly summarizes the main change: sparse KV offload and GPU metadata publication.
Description check	✅ Passed	The description explains the implementation, limitations, and test coverage in detail. It includes the required Description, Test Coverage, and PR Checklist sections. It does not state whether the req…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Inline comments:
Review comments at
@cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp:
- Line 214: Update queryLockLevel and the prefill reuse path so a host-locked
sparse page is not reused with an incompatible kHotLevel lock: provide prefill a
private GPU copy or treat the match as a cache miss, including when
_commitBlock() rebases onto it. Update
SharedPrefillOwnerDefersDemotionAcrossDecodeResume to assert recovery rather
than expecting LogicError.

Review comments at
@tensorrt_llm/_torch/pyexecutor/kv_cache/kv_cache_manager_v2.py:
- Around line 5774-5782: Update the guard in the batch metadata path to raise
only when sparse history pages are actually offloaded, checking sparse groups’
PageStorageSnapshot.cache_levels instead of relying only on history_length.
Preserve GPU-resident sparse decode; if the implementation intentionally
disallows all sparse decode, validate that configuration during initialization
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cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/AGENTS.md
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/CMakeLists.txt
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/batch.cpp
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/batch.h
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.h
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.cpp
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.h
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/lifeCycleRegistry.h
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/page.cpp
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/page.h
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.cpp
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.h
cpp/tensorrt_llm/nanobind/batch_manager/kvCacheManagerV2.cpp
cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ColdPageTest.cpp
tensorrt_llm/_torch/pyexecutor/kv_cache/kv_cache_manager_v2.py
tensorrt_llm/runtime/kv_cache_manager_v2/__init__.py
tensorrt_llm/runtime/kv_cache_manager_v2/__init__.pyi
tests/unittest/_torch/executor/kv_cache/test_kv_cache_v2_scheduler.py
tests/unittest/kv_cache_manager_v2_tests/test_kv_cache_manager_v2.py

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Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

Restore host-locked sparse prefixes into one shared GPU allocation for prefill admission, resume, prefetch, and rebasing. Order transfers after all readers, update every owner, and fence source-slot reuse. Retain deferred offload for decoding owners so publication retries after prefill releases its GPU requirement, even without history growth. Cover GPU exhaustion, copy failures, shared metadata, and reader ordering. Validation: 145 isolated native tests and 40 Python runtime checks passed on A30; 12 performance cases skipped. Full production package and CI wrapper validation remain unverified. Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

Check page-storage snapshots after sparse metadata publication instead of inferring offload from decode history length. Allow GPU-resident sparse history and reject mapped host pages across scheduled requests and sparse layer groups. Add regressions for GPU-only and mixed mappings, invalid slots, per-layer offsets, and publication-triggered offload. Validation: reproduced four false-rejection cases before the fix; 18 focused mock cases and pre-commit checks pass. Full pytest collection remains blocked by missing tensorrt_llm.bindings. Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

cascade812 · 2026-10-05T22:43:22Z

/bot run

tensorrt-cicd · 2026-10-05T22:52:22Z

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PR_Github #76271 [ run ] completed with state FAILURE. Commit: 999811c
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cascade812 · 2026-10-06T16:44:26Z

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Preserve sparse metadata membership and reader ordering with main's beam-aware page-index handling. Restore the request row lookup after resume and adapt scheduler regressions to beam admission and copy limits. Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

cascade812 · 2026-10-06T17:42:53Z

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Actionable comments posted: 2

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Inline comments:
Review comments at
@cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp:
- Line 2949: In the page-storage snapshot path, change the API lock from shared
to exclusive so concurrent calls to Page::status() cannot race while updating
the custom reference count. Update the lock acquisition near Page::status();
CachedCudaEvent’s shared-pointer copies do not require changes.
- Around line 244-247: Update `_offloadSparseHistory` to iterate only over the
existing rows in the block’s `pages` collection, avoiding `_page` lookups for
missing beam rows; also guard the row lookup in `getPageStorageSnapshot` before
accessing `pages.at(beamIdx)`.

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📒 Files selected for processing (12)

cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.h
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCacheManager.h
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/page.cpp
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/page.h
cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/storageManager.h
cpp/tensorrt_llm/nanobind/batch_manager/kvCacheManagerV2.cpp
tensorrt_llm/_torch/pyexecutor/kv_cache/kv_cache_manager_v2.py
tensorrt_llm/runtime/kv_cache_manager_v2/__init__.py
tensorrt_llm/runtime/kv_cache_manager_v2/__init__.pyi
tests/unittest/_torch/executor/kv_cache/test_kv_cache_v2_scheduler.py
tests/unittest/kv_cache_manager_v2_tests/test_kv_cache_manager_v2.py

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Iterate existing beam rows during sparse history offload and skip absent shared-prompt rows in storage snapshots. Acquire the exclusive manager lock when snapshot reads update non-atomic holder reference counts. Add regression coverage and provide dense buffer metadata in both mocked manager constructors to fix the CPU CI failures. Validation: 96 native KVCM V2 tests and 45 targeted Python tests passed. All 16 reported CI failures reproduced before the fixture fix. Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

cascade812 · 2026-10-06T22:26:20Z

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🧹 Nitpick comments (1)

cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ConcurrencyTest.cpp (1)
139-145: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Synchronize with the snapshot lock attempt.

started is signaled before getPageStorageSnapshot attempts mManager->lockExclusive(). If the worker is delayed after signaling, the 100 ms timeout can pass even if the snapshot no longer takes that lock. Add a test hook that confirms the worker reached the exclusive-lock attempt before checking that the snapshot remains blocked until apiLock is released.
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Review comment at
@cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ConcurrencyTest.cpp around
lines 139 - 145:
Update the concurrency test around getPageStorageSnapshot so started signals
only after the worker reaches the mManager->lockExclusive() attempt, using a
test hook or equivalent synchronization. Wait for that signal before asserting
snapshotFuture remains blocked until apiLock is released.

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Nitpick comments:
Review comments at
@cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ConcurrencyTest.cpp:
- Around line 139-145: Update the concurrency test around getPageStorageSnapshot
so started signals only after the worker reaches the mManager->lockExclusive()
attempt, using a test hook or equivalent synchronization. Wait for that signal
before asserting snapshotFuture remains blocked until apiLock is released.

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cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp
cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ColdPageTest.cpp
cpp/tests/unit_tests/batch_manager/kvCacheManagerV2ConcurrencyTest.cpp
tests/unittest/_torch/executor/kv_cache/test_kvcm2_integration.py

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cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp

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tensorrt-cicd · 2026-10-06T22:34:09Z

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github-actions · 2026-10-07T06:54:20Z

Automatically added "ci: full pre-merge approved" because this PR has satisfied the required GitHub review approvals. Unresolved review conversations and other required checks remain independent merge requirements.

cascade812 · 2026-10-07T17:23:37Z

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cascade812 · 2026-10-07T22:16:42Z

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Main's NVIDIA#19896 (2681ed1) moved PyTorchModelEngine's decoder execution into DecoderRunner (engine/runners/decoder/runner.py) and the encoder-decoder fast path into EncoderDecoderRunner, so this branch's model_engine.py changes conflicted. model_engine.py is main's; the branch's changes move to where that code now lives: - DecoderRunner, from NVIDIA#19816 (U1): the step-copy gather, the staged previous batch / position indices, gather_ids written by copy_to_device_if_changed, no num_accepted_draft_tokens buffer, and the CUDA graphs' static inputs; from NVIDIA#19814 (U3): the gather of vocabulary-sharded logits for post-processors. - EncoderDecoderRunner: its previous_batch_indices_cuda write clears the staged batch indices. - The two tests that called the moved members call the runner. Main's other commits since f891b3d: NVIDIA#19484, NVIDIA#19892, NVIDIA#19409, NVIDIA#19553, NVIDIA#19957, NVIDIA#19749, NVIDIA#19585, NVIDIA#19766, NVIDIA#19963, NVIDIA#19588, NVIDIA#19600, NVIDIA#19825, NVIDIA#19821, NVIDIA#19930, NVIDIA#18485. Signed-off-by: Vasanth Sabavat <vsabavat@nvidia.com>

…nd Batch Squash of the kvcm2-sparse-attention-api branch, replayed onto main after reverting NVIDIA#19821. That PR is main's own lineage of sparse KV offload; this is ours, and the two cannot both be present. Sparse buffers are declared per buffer, so one layer may hold a sparse buffer beside a dense one and a pool group may mix the two. Their pages are host memory, device-mapped, and read through a per-request GPU cache arena rather than directly, so the device quota does not pay for them. Because a slot spans every pool of its group, a sparse pool's row count follows from the device-backed pools the quota does size -- which left it unbounded. KVCacheManagerConfig::hostSparsePoolQuota bounds it, taken by the allocator as a second budget over a disjoint set of the same pools rather than as a clamp applied afterwards, so a group bound by one budget releases what it does not use of the other. The division itself is driven by all-bytes demand: each group's demand at a spending level is what its share of that level buys of its own all-bytes cost per slot, bisected against both budgets, with a bounded greedy finish spending the integral remainder on whichever group sits lowest in A(pg,n)/r. Feeding the allocator the normalised all-bytes ratio of its own output returns the same slot counts, which is what stops _needAdjustment re-firing on an unchanged profile. Batch holds the per-step page table: members are seated in rows, their page indices written directly into one pinned staging block that publish() uploads once. move() relocates a member between rows without ending membership, so the arena lease and its residency survive, and operator[] reads a row back. The staging rows are read-only from outside, and a debug check at KvCache::updateBasePageIndex -- where every page lock and unlock writes -- catches a mutation racing a publish still reading them. Conflicts with main were resolved keeping both sides' intent: NVIDIA#19727's optional reuse groups and private-slot bookkeeping, NVIDIA#20086's retention binding and AttnLifeCycle's isSparse/reusePolicy, main's tierCommitUnit and max-quota rejection, and its removal of the obsolete warmup paths (NVIDIA#20253). Pool groups are now keyed on reuse policy together with per-pool sparsity. Staging buffers take main's StaticHostMem, which suits an allocate-once buffer better than HostMem's fill worker and per-unit registration. Builds clean and deploys. Validated on an H100: the KVCM2 suite is green (321 tests), the decoder warmup suite is green (110 tests), and the KVCM2/sparse integration suite shows no regression against this host's pre-existing failures. Replaying the branch onto main's refactors needed six repairs that neither the textual merge nor lint could surface: - The MLA generation RoPE path: main extracted _mla_rope_generation_impl and inlined the page-table arguments, which a latent write target has to override. They are parameters again. - Decode-only warmup: main moved model_engine.py's warmup into DecoderWarmup and DecoderCudaGraphs, so the four hooks this branch had there were lost. They are back in the new homes, and the autotuner one now routes through main's own generation_only rather than reintroducing a second flag. - HostSlotPool gained a vmSize and backing options upstream. Sparse pools in a GpuPoolGroup pass them, and that group now waits for the fill at allocation, the way HostPoolGroup does, instead of forcing a synchronous fill. - storageManager.cpp lost a closing brace in the merge, nesting five definitions inside computeSlotCountForLevel. - The NVIDIA#19821 revert took three nanobind bindings with it that belong to NVIDIA#20086 (get_page_priorities, prefetch_reuse) rather than to NVIDIA#19821. Restored. - NVIDIA#20086 also left one assertion against NVIDIA#19821's get_page_storage_snapshot; it now reads page placement through _introspection, which this lineage keeps. Signed-off-by: Yao Yao <lowsfer@users.noreply.github.com>

…ned up Regenerates the trtllm-serve schema snapshots, which the new sparse offload config left stale: --check rejects them and the CPU schema tests fail. Restores KVCacheManagerV2.shutdown()'s call to the sharing lender's _on_shutdown(). It was collateral of removing NVIDIA#19821's sparse_metadata_batch, and nothing else called it, so a waiting lease would never be told to stop. A Batch row reused by a new member inherited the previous occupant's write-back watermark, which defeats the guard in KvCache::resize that stops history advancing past what has been written back. Seating now derives the watermark from the member's own history, and leaving requires the two to agree. Also: KvCache::close() refuses while seated, for the reason suspend() and resume() already do -- clearing blocks writes through the Batch's staged row; the resize shortcut asks both predicates before applying either, so a resize only one of them can take no longer leaves capacity advanced; the sparse arena reservation comes off whichever budget bound, not only max_gpu_total_bytes; ratio_to_slot_count_list() requires second_pools alongside second_quota, which otherwise charged every pool to the second budget; the Batch bindings that seat, unseat and move members release the GIL as move already did; the out ndarray parameters take .noconvert() so a mismatched tensor is refused rather than written into a discarded copy; and the paired-write check skips a batch with no member seated, where it could not retire the layer anyway. Signed-off-by: Yao Yao <lowsfer@users.noreply.github.com>

The guide's file list and overview lost their Batch entry with the NVIDIA#19821 revert, which described that lineage's Batch rather than this one, and never gained entries for the sparse cache or the index conversion. A reader was left with a dangling reference: the text mentions "Batch publication" without the file list introducing Batch at all. Adds the entries, a section on what Batch owns and what publish() promises, and pointers to the two design documents nothing referenced. Signed-off-by: Yao Yao <lowsfer@users.noreply.github.com>

cascade812 added 3 commits October 1, 2026 18:00

Batched GPU-to-CPU demotion and source release

98e190e

Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

trigger sparse offload during decode

25d01e5

Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

CPU metadata and GPU publication

2df6cb9

Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

github-actions Bot assigned cascade812 Oct 2, 2026

cascade812 added the api-compatible Accepted LLM API contract change that is backwards-compatible label Oct 2, 2026 — with ChatGPT Codex Connector

cascade812 marked this pull request as ready for review October 5, 2026 02:54

cascade812 requested a review from a team as a code owner October 5, 2026 02:54

cascade812 requested review from SimengLiu-nv and liji-nv October 5, 2026 02:54

coderabbitai Bot reviewed Oct 5, 2026

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Comment thread cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp Resolved

Comment thread tensorrt_llm/_torch/pyexecutor/kv_cache/kv_cache_manager_v2.py Resolved

cascade812 added 3 commits October 4, 2026 21:11

[None][fix] initialize CUDA stream pool before test gates

c7bcc26

Signed-off-by: Guiju Zhang <7135567+cascade812@users.noreply.github.com>

cascade812 requested a review from lowsfer October 5, 2026 23:14

coderabbitai Bot reviewed Oct 6, 2026

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Comment thread cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp Resolved

Comment thread cpp/tensorrt_llm/batch_manager/kv_cache_manager_v2/kvCache.cpp Resolved

coderabbitai Bot reviewed Oct 6, 2026

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liji-nv approved these changes Oct 7, 2026

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trtllm-agent added the ci: full pre-merge approved label Oct 7, 2026

cascade812 merged commit ce2e2f8 into NVIDIA:main Oct 8, 2026

cascade812 mentioned this pull request Oct 8, 2026

[TRTLLM-16289][feat] Wire DeepSeek-V4 sparse KV offload into the runtime #20003

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coderabbitai Bot mentioned this pull request Oct 10, 2026

[TRTLLM-16282][feat] Keep sparse GPU KV pages private per request #20067

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