delta_for: Hoist end() out of the loop check#30864
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Avoid rebuilding the default end iterator on every scanned element. end() didn't get optimized out and it's not entirely free in this iterator's case. Hoise it out manually. Possibly this addresses some noise we are seeing.
Amortize start/stop timer overhead for fast find benchmarks.
StephanDollberg
requested review from
WillemKauf,
ballard26,
Copilot and
travisdowns
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Pull request overview
This PR reduces iterator-related overhead in delta_for searches by caching end() iterators outside tight loops, and updates the associated micro-benchmark to batch find() calls and report operation counts to the perf harness.
Changes:
- Hoist
end()/this->end()out of loop conditions indeltafor_frame::pred_searchand bothdeltafor_column::pred_searchimplementations. - Update
delta_for_bench.ccfind_testto perform batchedfind()calls and return the batch size so perf results are normalized per operation.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
src/v/utils/tests/delta_for_bench.cc |
Batch find() benchmark iterations and return operation count for perf normalization. |
src/v/utils/delta_for.h |
Cache end() iterators to avoid reconstructing them on every loop condition check during scans. |
Collaborator
CI test resultstest results on build#86095 |
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Avoid rebuilding the default end iterator on every scanned element.
end() didn't get optimized out and it's not entirely free in this
iterator's case. Hoise it out manually.
Possibly this addresses some noise we are seeing.
Backports Required
Release Notes