[Bugfix][NIXL] Include transfer mode (push/pull) in the compatibility hash - #50620
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… hash The push (WRITE) and pull (READ) NIXL connectors use incompatible transfer protocols, but nothing currently prevents a push connector and a pull connector from completing a handshake with each other. Add the transfer mode to the NIXL compatibility hash so mismatched connectors are rejected early with a clear message instead of failing later during transfer. - `NixlBaseConnectorWorker._TRANSFER_MODE = "pull"`, overridden to `"push"` in `NixlPushConnectorWorker`; threaded into `compute_nixl_compatibility_hash`. - Bump NIXL connector version 5 -> 6. - Add a unit test and a docs note under "What must match". Follow-up to vllm-project#49230 (addresses review feedback from @iyastreb). Note: vllm-project#49230 also bumps the connector version to 6; whichever of the two lands second should renumber to 7. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Tzu-Ling <tzulingk@nvidia.com>
Advertise the connector's transfer mode (push vs pull) in the kv_transfer_params returned by the scheduler, so an external router can distinguish a pull (READ) producer from a push (WRITE) one (see vllm-project/router#187). - Add `_TRANSFER_MODE` to the scheduler classes (base = "pull", overridden to "push" in `NixlPushConnectorScheduler`). - Emit `transfer_mode` in the `kv_transfer_params` dict from both the pull and push `request_finished` paths. - Test the pull path end-to-end and the schedulers' advertised modes. Addresses review feedback from @iyastreb. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Tzu-Ling <tzulingk@nvidia.com>
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… hash (vllm-project#50620) Signed-off-by: Tzu-Ling <tzulingk@nvidia.com> Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Alessandra005 <aurib032@fiu.edu>
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… hash (vllm-project#50620) Signed-off-by: Tzu-Ling <tzulingk@nvidia.com> Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Wyett <wyettzeng@gmail.com>
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Overview:
Include the NIXL transfer mode (push vs pull) in the connector so a push (WRITE) connector and a pull (READ) connector can never be paired, and so an external router can distinguish them. Follow-up to #49230 (now merged), addressing review feedback from @iyastreb (#49230 thread, this PR's thread).
Details:
The push (
NixlPushConnector, WRITE) and pull (NixlConnector, READ) connectors use incompatible transfer protocols, but nothing prevented them from being paired across prefill/decode, and the transfer mode wasn't visible to an external router.Compatibility hash (worker side):
NixlBaseConnectorWorker._TRANSFER_MODE = "pull", overridden to"push"inNixlPushConnectorWorker, threaded intocompute_nixl_compatibility_hash.transfer_modeto the compatibility-hash factors so mismatched connectors are rejected early at handshake with a clear message.Router support (scheduler side):
NixlBaseConnectorScheduler._TRANSFER_MODE = "pull", overridden to"push"inNixlPushConnectorScheduler.transfer_modein thekv_transfer_paramsreturned by both the pull and pushrequest_finishedpaths, so an external router can route pull vs push producers. Consumed by vllm-project/router#187.Not a duplicate: this transfer-mode work was split out of #49230 (which fixed the speculative-config factors) to keep that PR scoped; no other open PR addresses mixing push/pull connectors.
Tests run:
.venv/bin/python -m pytest tests/v1/kv_connector/unit/test_nixl_connector.py -k "transfer_mode_changes_compatibility_hash or scheduler_advertises_transfer_mode or speculative_config_compatibility_hash" -q— passed.pre-commit run --files <the 8 changed files>— all applicable hooks passed.AI assistance was used to investigate, implement, and test this change. Every changed line was reviewed by the human submitter before submission.
Where should the reviewer start?
vllm/distributed/kv_transfer/kv_connector/v1/nixl/metadata.py—compute_nixl_compatibility_hash(newtransfer_modefactor + version bump).base_worker.py/push_worker.py— worker_TRANSFER_MODE.base_scheduler.py/pull_scheduler.py/push_scheduler.py— scheduler_TRANSFER_MODEemitted intokv_transfer_params.tests/v1/kv_connector/unit/test_nixl_connector.py— hash test, scheduler-mode test, and the pullkv_transfer_paramsassertion.