rustls-bench: short circuit single threaded tests #2583
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #2583 +/- ##
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Coverage 95.28% 95.28%
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Files 97 97
Lines 21581 21581
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Hits 20564 20564
Misses 1017 1017 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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cpu
approved these changes
Jul 29, 2025
Benchmark resultsInstruction countsSignificant differencesThere are no significant instruction count differences Other differencesClick to expand
Wall-timeSignificant differencesThere are no significant wall-time differences Other differencesClick to expand
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This is quite mysterious. I've been looking at doing a refresh of https://rustls.dev/perf/2024-10-18-report/ and noticed a regression in our bulk speeds. That bisected to d1c33f8 which is odd because all the bulk testing is single threaded, and so that change should be ~free (yes, we make a new thread, but the main thread just waits for it to finish so there should be no contention and any large costs -- like allocating and faulting in the new stack -- should be amortized over the size of the run.)
What is more weird is that this regression is not visible on my laptop (AMD Ryzen 9 7940HS), but only the x86 benchmark box (Intel Xeon E-2386G).
This change restores the previous behaviour for single threaded tests by running them on the calling thread.
(these numbers should be comparable to the ones in the first two rows of the table on https://rustls.dev/perf/2024-10-18-report/)