fix(bench): explicit timers don't force high precision measurements (#20272)
Disables `BenchContext::start()` and `BenchContext::end()` for low
precision benchmarks (less than 0.01s per iteration). Prints a warning
when they are used in such benchmarks, suggesting to remove them.
```ts
Deno.bench("noop", { group: "noops" }, () => {});
Deno.bench("noop with start/end", { group: "noops" }, (b) => {
b.start();
b.end();
});
```
Before:
```
cpu: 12th Gen Intel(R) Core(TM) i9-12900K
runtime: deno 1.36.2 (x86_64-unknown-linux-gnu)
file:///home/nayeem/projects/deno/temp3.ts
benchmark time (avg) iter/s (min … max) p75 p99 p995
----------------------------------------------------------------------------- -----------------------------
noop 2.63 ns/iter 380,674,131.4 (2.45 ns … 27.78 ns) 2.55 ns 4.03 ns 5.33 ns
noop with start and end 302.47 ns/iter 3,306,146.0 (200 ns … 151.2 µs) 300 ns 400 ns 400 ns
summary
noop
115.14x faster than noop with start and end
```
After:
```
cpu: 12th Gen Intel(R) Core(TM) i9-12900K
runtime: deno 1.36.1 (x86_64-unknown-linux-gnu)
file:///home/nayeem/projects/deno/temp3.ts
benchmark time (avg) iter/s (min … max) p75 p99 p995
----------------------------------------------------------------------------- -----------------------------
noop 3.01 ns/iter 332,565,561.7 (2.73 ns … 29.54 ns) 2.93 ns 5.29 ns 7.45 ns
noop with start and end 7.73 ns/iter 129,291,091.5 (6.61 ns … 46.76 ns) 7.87 ns 13.12 ns 15.32 ns
Warning start() and end() calls in "noop with start and end" are ignored because it averages less than 0.01s per iteration. Remove them for better results.
summary
noop
2.57x faster than noop with start and end
```
2023-08-26 05:29:45 -04:00
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cpu: [WILDCARD]
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runtime: deno [WILDCARD] ([WILDCARD])
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[WILDCARD]/explicit_start_and_end_low_precision.ts
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benchmark time (avg) iter/s (min … max) p75 p99 p995
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----------------------------------------------------------------------------- -----------------------------
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noop with start and end [WILDCARD] [WILDCARD]/iter[WILDCARD]([WILDCARD] … [WILDCARD]) [WILDCARD]
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Warning: start() and end() calls in "noop with start and end" are ignored because it averages less
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2023-10-10 09:40:36 -04:00
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than 10µs per iteration. Remove them for better results.
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2023-12-17 17:57:14 -05:00
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