1 //! Benchmarking module.
2 pub use std::hint::black_box;
7 test_result::TestResult,
8 types::{TestDesc, TestId},
15 use std::panic::{catch_unwind, AssertUnwindSafe};
16 use std::sync::{Arc, Mutex};
17 use std::time::{Duration, Instant};
19 /// Manager of the benchmarking runs.
21 /// This is fed into functions marked with `#[bench]` to allow for
22 /// set-up & tear-down before running a piece of code repeatedly via a
27 summary: Option<stats::Summary>,
32 /// Callback for benchmark functions to run in their body.
33 pub fn iter<T, F>(&mut self, mut inner: F)
37 if self.mode == BenchMode::Single {
38 ns_iter_inner(&mut inner, 1);
42 self.summary = Some(iter(&mut inner));
45 pub fn bench<F>(&mut self, mut f: F) -> Option<stats::Summary>
47 F: FnMut(&mut Bencher),
54 #[derive(Debug, Clone, PartialEq)]
55 pub struct BenchSamples {
56 pub ns_iter_summ: stats::Summary,
60 pub fn fmt_bench_samples(bs: &BenchSamples) -> String {
62 let mut output = String::new();
64 let median = bs.ns_iter_summ.median as usize;
65 let deviation = (bs.ns_iter_summ.max - bs.ns_iter_summ.min) as usize;
69 "{:>11} ns/iter (+/- {})",
70 fmt_thousands_sep(median, ','),
71 fmt_thousands_sep(deviation, ',')
75 write!(output, " = {} MB/s", bs.mb_s).unwrap();
80 // Format a number with thousands separators
81 fn fmt_thousands_sep(mut n: usize, sep: char) -> String {
83 let mut output = String::new();
84 let mut trailing = false;
85 for &pow in &[9, 6, 3, 0] {
86 let base = 10_usize.pow(pow);
87 if pow == 0 || trailing || n / base != 0 {
89 write!(output, "{}", n / base).unwrap();
91 write!(output, "{:03}", n / base).unwrap();
104 fn ns_iter_inner<T, F>(inner: &mut F, k: u64) -> u64
108 let start = Instant::now();
112 start.elapsed().as_nanos() as u64
115 pub fn iter<T, F>(inner: &mut F) -> stats::Summary
119 // Initial bench run to get ballpark figure.
120 let ns_single = ns_iter_inner(inner, 1);
122 // Try to estimate iter count for 1ms falling back to 1m
123 // iterations if first run took < 1ns.
124 let ns_target_total = 1_000_000; // 1ms
125 let mut n = ns_target_total / cmp::max(1, ns_single);
127 // if the first run took more than 1ms we don't want to just
128 // be left doing 0 iterations on every loop. The unfortunate
129 // side effect of not being able to do as many runs is
130 // automatically handled by the statistical analysis below
131 // (i.e., larger error bars).
134 let mut total_run = Duration::new(0, 0);
135 let samples: &mut [f64] = &mut [0.0_f64; 50];
137 let loop_start = Instant::now();
139 for p in &mut *samples {
140 *p = ns_iter_inner(inner, n) as f64 / n as f64;
143 stats::winsorize(samples, 5.0);
144 let summ = stats::Summary::new(samples);
146 for p in &mut *samples {
147 let ns = ns_iter_inner(inner, 5 * n);
148 *p = ns as f64 / (5 * n) as f64;
151 stats::winsorize(samples, 5.0);
152 let summ5 = stats::Summary::new(samples);
154 let loop_run = loop_start.elapsed();
156 // If we've run for 100ms and seem to have converged to a
158 if loop_run > Duration::from_millis(100)
159 && summ.median_abs_dev_pct < 1.0
160 && summ.median - summ5.median < summ5.median_abs_dev
165 total_run += loop_run;
166 // Longest we ever run for is 3s.
167 if total_run > Duration::from_secs(3) {
171 // If we overflow here just return the results so far. We check a
172 // multiplier of 10 because we're about to multiply by 2 and the
173 // next iteration of the loop will also multiply by 5 (to calculate
175 n = match n.checked_mul(10) {
187 monitor_ch: Sender<CompletedTest>,
191 F: FnMut(&mut Bencher),
193 let mut bs = Bencher { mode: BenchMode::Auto, summary: None, bytes: 0 };
195 let data = Arc::new(Mutex::new(Vec::new()));
198 io::set_output_capture(Some(data.clone()));
201 let result = catch_unwind(AssertUnwindSafe(|| bs.bench(f)));
203 io::set_output_capture(None);
205 let test_result = match result {
207 Ok(Some(ns_iter_summ)) => {
208 let ns_iter = cmp::max(ns_iter_summ.median as u64, 1);
209 let mb_s = bs.bytes * 1000 / ns_iter;
211 let bs = BenchSamples { ns_iter_summ, mb_s: mb_s as usize };
212 TestResult::TrBench(bs)
215 // iter not called, so no data.
216 // FIXME: error in this case?
217 let samples: &mut [f64] = &mut [0.0_f64; 1];
218 let bs = BenchSamples { ns_iter_summ: stats::Summary::new(samples), mb_s: 0 };
219 TestResult::TrBench(bs)
221 Err(_) => TestResult::TrFailed,
224 let stdout = data.lock().unwrap().to_vec();
225 let message = CompletedTest::new(id, desc, test_result, None, stdout);
226 monitor_ch.send(message).unwrap();
229 pub fn run_once<F>(f: F)
231 F: FnMut(&mut Bencher),
233 let mut bs = Bencher { mode: BenchMode::Single, summary: None, bytes: 0 };