README.md

minstant

A drop-in replacement for std::time::Instant that measures time with high performance and high accuracy powered by TSC.

Usage

[dependencies]
minstant = "0.1"

let start = minstant::Instant::now();

// Code snipppet to measure

let duration: std::time::Duration = start.elapsed();

Motivation

This library is used by a high performance tracing library minitrace-rust. The main purpose is to use TSC on x86 processors to measure time at high speed without losing much accuracy.

Platform Support

Currently, only the Linux on x86 or x86_64 is backed by TSC. On other platforms, minstant falls back to std::time. If TSC is unstable, it will also fall back to std::time.

If speed is privileged over accuracy when fallback occurs, you can use fallback-coarse feature to use coarse time:

[dependencies]
minstant = { version = "0.1", features = ["fallback-coarse"] }

Benchmark

Benchmark platform is Intel(R) Xeon(R) CPU E5-2630 v4 @ 2.20GHz on CentOS 7.

> cargo criterion

Instant::now()/minstant             time:   [10.449 ns 10.514 ns 10.619 ns]
Instant::now()/quanta               time:   [31.467 ns 31.628 ns 31.822 ns]
Instant::now()/std                  time:   [26.831 ns 26.924 ns 27.016 ns]
minstant::Anchor::new()             time:   [46.987 ns 47.243 ns 47.498 ns]
minstant::Instant::as_unix_nanos()  time:   [15.287 ns 15.318 ns 15.350 ns]