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perf(cuda): disable timing on pinned transfer events - #10714

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0ax1 merged 1 commit into
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ad/cuda-pinned-event-flags
Oct 23, 2026
Merged

0ax1 merged 1 commit into
developfrom
ad/cuda-pinned-event-flags

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@0ax1

@0ax1 0ax1 commented Oct 23, 2026 •

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Problem

Pinned-transfer completion events record timing that reclamation does not use.

Solution

Replace BLOCKING_SYNC with DISABLE_TIMING.

Assessment

Host event waits become busy-waits, trading CPU usage for different wait behavior. Independent of event reuse; based on #10726.

@codspeed

codspeed Bot commented Oct 23, 2026 •

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Merging this PR will regress 2 benchmarks

2 warnings, 1 note

⚠️ Walltime results may be unreliable

Some benchmarks used the Walltime instrument outside CodSpeed Macro Runners, which can make the results inconsistent.

Learn more about Macro Runners

See affected benchmarks

⚠️ 14 benchmarks are dominated by system calls

System calls cannot be simulated consistently and are left out of the measure. The reported value understates the real cost. Switch to the Walltime instrument to measure them.

Learn more about system calls

See affected benchmarks

ℹ️ 40 benchmarks have no flamegraph

The flamegraph wasn't generated: the symbols of the profiling trace could not be resolved, because no information about the language frames was collected.

See affected benchmarks

⚡ 3 improved benchmarks
❌ 2 regressed benchmarks
✅ 2403 untouched benchmarks
⏩ 12 skipped benchmarks1
🗄️ 43 archived benchmarks run2

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

Mode Benchmark BASE HEAD Efficiency
❌ Walltime random_rotating_avx512[(0.5, 0.5, "self_50pct_mask_50pct")] 8.2 µs 9.2 µs -10.85%
❌ Walltime bitpack_blocked_compress_avx2 6.8 µs 7.6 µs -10.26%
⚡ CPU Simulation decode_primitives[i64, (1000, 8)] 37.6 µs 24 µs +56.62%
⚡ CPU Simulation take[routing/alternating_chunks/primitive/nonnull/chunks=32/indices=1000] 247.1 µs 196.7 µs +25.6%
⚡ Walltime words_gather_dispatch_neon[65536] 2 µs 1.8 µs +10.18%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.


Comparing ad/cuda-pinned-event-flags (08955de) with develop (e083440)

Open in CodSpeed

Footnotes

  1. 12 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

  2. 43 benchmarks were run, but are now archived. If they were deleted in another branch, consider rebasing to remove them from the report. Instead if they were added back, click here to restore them. ↩

@0ax1 0ax1 added the changelog/performance A performance improvement label Oct 23, 2026 — with ChatGPT Codex Connector
@0ax1
0ax1 changed the base branch from develop to ad/ctutils-security-update October 23, 2026 13:13
@0ax1
0ax1 force-pushed the ad/cuda-pinned-event-flags branch from 9271a1d to 59b0d68 Compare October 23, 2026 13:13
@0ax1
0ax1 requested a review from robert3005 October 23, 2026 14:50
@0ax1
0ax1 marked this pull request as ready for review October 23, 2026 14:51
Base automatically changed from ad/ctutils-security-update to develop October 23, 2026 15:34
Replace BLOCKING_SYNC with DISABLE_TIMING on pinned-buffer events. This also changes host event waits from blocking to busy-waiting; buffer ownership and completion-event reuse are unchanged.

Original-commit: 231277f878
Signed-off-by: Alexander Droste <alexander.droste@protonmail.com>
@0ax1
0ax1 force-pushed the ad/cuda-pinned-event-flags branch from 59b0d68 to 08955de Compare October 23, 2026 15:40
@0ax1
0ax1 merged commit 3258a3b into develop Oct 23, 2026
133 of 139 checks passed
@0ax1
0ax1 deleted the ad/cuda-pinned-event-flags branch October 23, 2026 17:08
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