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docs(bench): narrow README performance tables - #32
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Drop the previous-JIT latency column, shorten headers, keep ratio cells on one line, and list statistically tied intervals below each table. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
One main table with QuickJS/Bun/quickjs-jit latency and quickjs-jit speed vs QuickJS and vs Bun, each labelled faster/slower/tied. Confidence intervals move to a collapsible table; regression and diagnostics keep their own table. Non-breaking hyphens keep every cell on one line. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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## Summary 0.12.10 regressed real gpui-shell renders (acceptance sample, one core): compute ran at 0.13x, mixed at 0.49x and panel at 0.82x the speed of 0.12.9. The 35-kernel jit-bench matrix could not show it: it polls the JIT after every batch and warms 640 calls, while gpui-shell never calls `Jit::poll` and is measured from the first frames. Three root causes, one commit each: - **`de40dca` Baseline demoted during the funded Tier2 trial.** Five rejected Tier2 profitability retries returned every Baseline to the interpreter until the trial installed. The retries only say the modeled Tier2 saving has not paid off; the runtime never measures the interpreter. Since P2 widened Tier 1 coverage, the trial waited behind other first Baselines on the single worker, so the layout kernel ran at interpreter speed for about 100 frames. Now only a Baseline whose fastest complete run is under 10 µs (entry bookkeeping can dominate, e.g. `return a + b`) is demoted. A longer one keeps running, and its trial moves to the front of the compile queue. The worker channel never holds more jobs than there are workers, so the backlog stays reorderable. - **`1680c2c` P2 opcodes slower than the interpreter in host code.** The panel builder's short helpers (closures, `push_this`, `typeof`, …) became native, with about 220 entries per render, at 0.8x the interpreter's speed. Stable-IC trials bypass the retry demotion, so nothing returned them. Automatic tiering now rejects functions containing any of the 52 opcodes Tier 1 gained in P2, with the reason 0.12.9 reported. `BaselineOnly`, `Optimize` and forced test tiers still compile them. (Chosen as the conservative option for 0.12.11; letting profitability measure the interpreter is the follow-up.) - **`8fa2a48` Retry backoff stretched without host polling.** Retries are evaluated only by maintenance, which ran every 64 hot ticks (about 31 frames) once the kernel was native. Maintenance is now due at the next retry, and exhausted retries queue the trial at the next maintenance. The demotion rule uses the fastest complete (non-OSR) Baseline run, so preemption or a partial OSR run cannot flip it. A generic "Tier2 first" queue order was tried and dropped. It exposed ordering hazards: a callee reaching Tier2 before its caller's Baseline loses call-link feedback, and `tagged_call_link` caught it. ## Performance **gpui-shell** (`emit_one_jit_acceptance_sample`, 10 retained process pairs, mean render µs): | Workload | Cores | 0.12.9 | 0.12.10 | this PR | vs 0.12.9 | vs 0.12.10 | | --- | --- | ---: | ---: | ---: | ---: | ---: | | compute | 1 | 15.1 | 127.1 | 10.3 | 1.5x (faster) | 12.3x (faster) | | compute | 2 | 16.3 | 62.4 | 10.2 | 1.6x (faster) | 6.6x (faster) | | mixed | 1 | 178.5 | 363.3 | 92.7 | 1.9x (faster) | 3.9x (faster) | | mixed | 2 | 179.2 | 180.1 | 92.4 | 1.9x (faster) | 2.0x (faster) | | panel | 1 | 812.0 | 981.4 | 803.7 | 1.03x (faster) | 1.3x (faster) | | panel | 2 | 806.9 | 987.9 | 805.5 | 1.00x (tied) | 1.2x (faster) | **jit-bench**, all 35 scenarios, `shared-js-multibatch-v3`, 30 retained processes per configuration, CPU 8. Full tables are in the README. - vs v0.12.10: 8 faster, 11 slower, 16 tied. The two large losses are the deliberate P2 deferral: `exceptions-sync` 0.21x and `for-of-array` 0.36x, back to QuickJS speed. The other nine are 0.5–3.6% slower; for three of them the unchanged interpreter moved by a similar amount. - vs QuickJS: 23 faster, 5 slower, 7 tied. - vs Bun: 0 of 35 faster. ## Tests - Regression tests, each verified to fail without its fix: `automatic_gpui_layout_kernel_keeps_baseline_until_tier2_trial`, `automatic_layout_kernel_reaches_tier2_without_host_polling`, `prioritized_request_is_taken_ahead_of_earlier_requests`, `dispatch_keeps_the_backlog_in_the_coordinator_while_workers_are_busy`. - Exception lowering tests moved to `BaselineOnly`. The settle tests assert the automatic deferral. The background tests follow bounded dispatch. - `cargo test -p quickjs-jit-runtime --release --features compiler,test-support`: 56 binaries, 987 tests pass, run twice. `cargo clippy --tests`: no warnings. ## Sanitizer CI The nightly sanitizer job had failed since the P0–P4 merge (#30), including on docs-only #31 and #32. It stopped at the first slow MSan test, so the ASan and TSan steps never ran. A local no-fail-fast run of the CI commands, also pinned to two cores to mimic the runner, found every remaining issue. No ASan memory error and no TSan data race was reported. - `2166391`: sanitizer builds default to a ten-minute compile budget. One MSan-instrumented Tier 1 compile took over 30 s on the runner and timed out on every retry. `object_fast_paths` now waits 300 s. A forced test tier ignores timed Tier2 losses, which timing noise alone could trigger. - `7f88490`: every fixed `let deadline = now + N s` in the JIT tests allows 5x under sanitizers. The `tier2_ownership` runner keeps calling until Tier 2 when the test expects it. `fast_entry`'s intentionally leaked state stays reachable for LeakSanitizer. The absolute-time entry-dominated demotion test is ignored under sanitizers: instrumentation slows the bookkeeping but not the generated code. - `36ddc59`: `frame_inline` waits for the linked Tier2 caller before counting generic calls. CI: MSan, ASan and TSan all pass. Locally, on two cores, 62/62 JIT test binaries pass under each sanitizer. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
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Summary
benchmarks/results/roadmap-889f7c1-paired-x86_64.json).Workload | QuickJS | Bun | quickjs-jit | vs QuickJS | vs Bun, with ms columns and quickjs-jit speed multiples labelled(faster),(slower)or(tied)from the 95% CI, e.g.48.8x (faster),0.54x (slower). A short legend explains the direction.1.0x (slower).<details>table.No measurements changed.
🤖 Generated with Claude Code