feat(nvsnap): enable UV_USE_IO_URING after CRIU SQ-array restore fix#225
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balajinvda wants to merge 1 commit into
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feat(nvsnap): enable UV_USE_IO_URING after CRIU SQ-array restore fix#225balajinvda wants to merge 1 commit into
balajinvda wants to merge 1 commit into
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libuv/uvloop servers (vLLM, e5-mistral) previously had to pin UV_USE_IO_URING=0 under criu-v2: the restored libuv SQPOLL io_uring ring aborted the event loop on the first epoll_ctl_flush (SIGABRT, nvsnap#107). Root cause was in CRIU's io_uring restore, which recreated a fresh ring but never rebuilt the SQ-array identity map (sq_array[i] = i) that liburing/libuv write once at setup; every restored submission then resolved to SQE 0 and completions never returned. The CRIU fork now rebuilds that identity map on restore (io-uring-cr commit 0a9963ed0). Pin the base build to it and re-enable UV_USE_IO_URING=1 on the single-GPU criu-v2 workloads. - versions.sh: NVSNAP_CRIU_REF -> 0a9963ed0; base v0.0.9; app v0.2.19. - vllm-small, vllm-8b, vllm-qwen32b, e5-mistral: UV_USE_IO_URING 0 -> 1. Validated e2e on aws-dev1 (kernel 6.8): all four checkpoint, restore, and serve inference with io_uring on, zero event-loop aborts. Co-Authored-By: Balaji Ganesan <bganesan@nvidia.com>
🛡️ CodeQL Analysis🚨 Found 2 issue(s) Severity Breakdown:
📋 Top Issues🔗 View full details in Security tab 🕐 Last updated: 2026-07-17 04:33:48 UTC | Commit: a9701c1 |
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Why
libuv/uvloop servers (vLLM, e5-mistral) had to pin
UV_USE_IO_URING=0under criu-v2 restore: the restored libuv SQPOLL io_uring ring aborted the event loop on the firstepoll_ctl_flush(SIGABRT). Root cause was in CRIU's io_uring restore — it recreated a fresh ring but never rebuilt the SQ-array identity map (sq_array[i] = i) that liburing/libuv write once at setup, so restored submissions all resolved to SQE 0 and completions never returned.What changed
0a9963ed0).versions.sh:NVSNAP_CRIU_REF->0a9963ed0; basev0.0.9; appv0.2.19.vllm-small,vllm-8b,vllm-qwen32b,e5-mistral:UV_USE_IO_URING0->1.Testing
Validated e2e on aws-dev1 (kernel 6.8) — all four checkpoint, restore, and serve inference with io_uring on, zero event-loop aborts:
Notes
Fix is general io_uring-restore correctness (not nvsnap-specific) and is upstreamable to checkpoint-restore/criu. Ref nvsnap#107.
Relates to #71