1#![allow(clippy::cast_precision_loss)]23use std::{4 ffi::OsString,5 mem,6 process::{Command, Stdio},7 time::Instant,8};910use anyhow::{Result, bail};11use nix::{libc, sys::wait::WaitStatus, unistd::Pid};1213#[derive(Debug, Clone)]14pub struct Stats {15 pub min: f64,16 pub max: f64,17 pub mean: f64,18 pub stddev: f64,19}2021impl Stats {22 fn from_samples(samples: &[f64]) -> Self {23 let n = samples.len() as f64;24 let mean = samples.iter().sum::<f64>() / n;25 let var = if samples.len() > 1 {26 samples.iter().map(|x| (x - mean).powi(2)).sum::<f64>() / (n - 1.0)27 } else {28 0.029 };30 Self {31 min: samples.iter().copied().fold(f64::INFINITY, f64::min),32 max: samples.iter().copied().fold(f64::NEG_INFINITY, f64::max),33 mean,34 stddev: var.sqrt(),35 }36 }37}3839#[derive(Debug, Clone)]40pub struct BenchResult {41 pub runs: u32,42 43 pub wall_secs: Stats,44 45 pub max_rss_kib: Stats,46}4748pub struct BenchOpts<'a> {49 pub program: &'a OsString,50 pub args: &'a [OsString],51 pub runs: u32,52 pub warmup: u32,53 pub output: bool,54}5556pub fn bench(opts: BenchOpts<'_>) -> Result<BenchResult> {57 if opts.runs == 0 {58 bail!("runs must be >= 1");59 }6061 for _ in 0..opts.warmup {62 run_once(opts.program, opts.args, opts.output)?;63 }6465 let mut wall = Vec::with_capacity(opts.runs as usize);66 let mut rss = Vec::with_capacity(opts.runs as usize);67 for _ in 0..opts.runs {68 let s = run_once(opts.program, opts.args, opts.output)?;69 wall.push(s.wall_secs);70 rss.push(s.max_rss_kib as f64);71 }7273 Ok(BenchResult {74 runs: opts.runs,75 wall_secs: Stats::from_samples(&wall),76 max_rss_kib: Stats::from_samples(&rss),77 })78}7980struct Sample {81 wall_secs: f64,82 max_rss_kib: i64,83}8485fn run_once(program: &OsString, args: &[OsString], silent: bool) -> Result<Sample> {86 let mut cmd = Command::new(program);87 cmd.args(args);88 if silent {89 cmd.stdout(Stdio::null()).stderr(Stdio::null());90 }9192 let start = Instant::now();93 let child = cmd.spawn()?;94 #[allow(95 clippy::cast_possible_wrap,96 reason = "it is signed, but libc didn't set unsigned for it"97 )]98 let pid = child.id() as libc::pid_t;99 100 mem::forget(child);101102 let mut status: libc::c_int = 0;103 let mut ru: libc::rusage = unsafe { mem::zeroed() };104 let waited = unsafe { libc::wait4(pid, &raw mut status, 0, &raw mut ru) };105 let elapsed = start.elapsed();106 if waited < 0 {107 return Err(std::io::Error::last_os_error().into());108 }109110 match WaitStatus::from_raw(Pid::from_raw(pid), status)? {111 WaitStatus::Exited(_, 0) => {}112 WaitStatus::Exited(_, code) => bail!("child exited with code {code}"),113 WaitStatus::Signaled(_, sig, _) => bail!("child killed by signal {sig:?}"),114 other => bail!("unexpected wait status: {other:?}"),115 }116117 Ok(Sample {118 wall_secs: elapsed.as_secs_f64(),119 max_rss_kib: ru.ru_maxrss,120 })121}122123#[cfg(target_os = "linux")]124pub fn bench_cmd(args: &[String], runs: u32, warmup: u32, output: bool) -> Result<()> {125 let program = std::ffi::OsString::from(&args[0]);126 let rest: Vec<std::ffi::OsString> = args[1..].iter().map(Into::into).collect();127 let r = bench(BenchOpts {128 program: &program,129 args: &rest,130 runs,131 warmup,132 output,133 })?;134 eprintln!(135 "runs: {} wall: {:.3}s ± {:.3}s [{:.3}..{:.3}]",136 r.runs, r.wall_secs.mean, r.wall_secs.stddev, r.wall_secs.min, r.wall_secs.max,137 );138 eprintln!(139 " max_rss: {} ± {} KiB [{}..{}]",140 r.max_rss_kib.mean.trunc(),141 r.max_rss_kib.stddev.trunc(),142 r.max_rss_kib.min.trunc(),143 r.max_rss_kib.max.trunc(),144 );145 Ok(())146}