| ## perf-event: a Rust interface to Linux performance monitoring |
| |
| *This is a nascent project. Tests are lacking. The design may change.* |
| |
| This uses the Linux [`perf_event_open`][man] API to access performance monitoring |
| hardware and software. Use `Builder` to create a perf event counter, then use |
| `enable` and `disable` to start and stop counting. Call `read` to get your |
| count. |
| |
| For example, this counts the number of cycles used by the call to `println!`. |
| Try adjusting the length of the vector to see the cycle count change. |
| |
| use perf_event::Builder; |
| |
| fn main() -> std::io::Result<()> { |
| let mut counter = Builder::new().build()?; |
| |
| let vec = (0..=51).collect::<Vec<_>>(); |
| |
| counter.enable()?; |
| println!("{:?}", vec); |
| counter.disable()?; |
| |
| println!("{} instructions retired", counter.read()?); |
| |
| Ok(()) |
| } |
| |
| Since we don't specify what sort of event we want to count, `Builder` defaults |
| to `PERF_COUNT_HW_INSTRUCTIONS` events, whose documentation says: |
| |
| > Retired instructions. Be careful, these can be affected by various issues, |
| > most notably hardware interrupt counts. |
| |
| The `examples` directory includes programs that count other sorts of events. |
| |
| [man]: http://man7.org/linux/man-pages/man2/perf_event_open.2.html |
| |
| ## See also |
| |
| The [`perfcnt`] crate provides more extensive coverage of the Linux |
| `perf_event_open` API than this crate. However, `perfcnt` does not build on |
| stable Rust. |
| |
| [`perfcnt`]: https://crates.io/crates/perfcnt |
