Follow-up C: Publish profile_bench results — README <1% claim partially supported - #29
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- Run snmalloc-rs/benches/profile_bench.rs end-to-end with --features profiling on Apple M4 Pro / macOS 26.3.1; capture mean / CI / median / stddev from target/criterion/*/new/estimates.json. - New docs/heap-profiling-benchmarks.md table-formats the raw numbers for the small_allocs / medium_allocs / mixed groups across the three variants (profile-off, profile-on-inactive, profile-on-active). - Compute ratio_idle and ratio_active per group; averages are ~1.024 in both configurations, max ratio is 1.0493 on medium_allocs/profile-on-inactive. All groups stay inside the bench harness's documented <=1.05 acceptance band. - Document the gap vs the existing "<1% overhead" README claim: small allocs support it (in noise), but medium and mixed land at ~3-5%. Recommend softening the README phrasing in a follow-up PR. - No groups hit the 20-minute time budget; full sweep ~85s wall-clock.
- Replace 'soften README claim' recommendation with link to ClickUp ticket 86aj0hfmc that drives medium/mixed under 1% - Keep reproduction caveats (Linux pinning, larger sample_size) - Per user direction: target stays; gap is a perf-regression follow-up, not a docs change
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Summary
Publishes
docs/heap-profiling-benchmarks.mdwith measured overhead from Phase 7.2's criterion bench suite.Machine: Apple M4 Pro / macOS 26.3.1 / 12 cores / rustc 1.95.0
Wall clock: ~85s for full 3-group × 3-variant sweep
Headline
Status
The README "<1% overhead at default sampling rate" claim is the design target. This measurement does not yet support it on
medium_allocsandmixed. The gap is being driven to closure in ClickUp ticket 86aj0hfmc (open). Investigation targets: cache-line alignment of the Sampler hot state, Phase 3.3 alloc-hook fast path, dealloc null-check predictor behavior, lazy-provider first-touch costs.Closes ClickUp ticket 86aj0h88j (the publish task). The perf gap is tracked separately.
Test plan
cargo bench --features profiling(all 3 groups completed, no skips)docs/heap-profiling-benchmarks.mdwell-formed markdown