79 lines
2.6 KiB
Rust
79 lines
2.6 KiB
Rust
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//! This is a simple Criterion Profiler implementation using pprof.
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//!
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//! It's mostly a direct copy from here: https://www.jibbow.com/posts/criterion-flamegraphs/
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use std::{fs::File, os::raw::c_int, path::Path};
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use criterion::profiler::Profiler;
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use pprof::ProfilerGuard;
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/// Small custom profiler that can be used with Criterion to create a flamegraph for benchmarks.
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/// Also see [the Criterion documentation on this][custom-profiler].
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///
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/// ## Example on how to enable the custom profiler:
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///
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/// ```
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/// mod perf;
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/// use perf::FlamegraphProfiler;
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///
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/// fn fibonacci_profiled(criterion: &mut Criterion) {
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/// // Use the criterion struct as normal here.
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/// }
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///
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/// fn custom() -> Criterion {
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/// Criterion::default().with_profiler(FlamegraphProfiler::new())
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/// }
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///
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/// criterion_group! {
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/// name = benches;
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/// config = custom();
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/// targets = fibonacci_profiled
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/// }
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/// ```
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///
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/// The neat thing about this is that it will sample _only_ the benchmark, and not other stuff like
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/// the setup process.
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///
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/// Further, it will only kick in if `--profile-time <time>` is passed to the benchmark binary.
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/// A flamegraph will be created for each individual benchmark in its report directory under
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/// `profile/flamegraph.svg`.
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///
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/// [custom-profiler]: https://bheisler.github.io/criterion.rs/book/user_guide/profiling.html#implementing-in-process-profiling-hooks
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pub struct FlamegraphProfiler<'a> {
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frequency: c_int,
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active_profiler: Option<ProfilerGuard<'a>>,
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}
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impl<'a> FlamegraphProfiler<'a> {
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pub fn new(frequency: c_int) -> Self {
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FlamegraphProfiler {
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frequency,
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active_profiler: None,
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}
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}
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}
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impl<'a> Profiler for FlamegraphProfiler<'a> {
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fn start_profiling(&mut self, _benchmark_id: &str, _benchmark_dir: &Path) {
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self.active_profiler = Some(ProfilerGuard::new(self.frequency).unwrap());
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}
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fn stop_profiling(&mut self, _benchmark_id: &str, benchmark_dir: &Path) {
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std::fs::create_dir_all(benchmark_dir)
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.expect("Can't create a directory to store the benchmarking report");
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let flamegraph_path = benchmark_dir.join("flamegraph.svg");
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let flamegraph_file = File::create(&flamegraph_path)
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.expect("File system error while creating flamegraph.svg");
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if let Some(profiler) = self.active_profiler.take() {
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profiler
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.report()
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.build()
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.expect("Can't build profiling report")
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.flamegraph(flamegraph_file)
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.expect("Error writing flamegraph");
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}
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}
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}
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