lightswitch 0.7.0

CPU profiler as a library for Linux suitable for on-demand and continuous profiling
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use std::io;
use std::os::raw::c_int;

use perf_event_open_sys as sys;
use perf_event_open_sys::bindings::perf_event_attr;

/// # Safety
pub unsafe fn setup_perf_event(cpu: i32, sample_freq: u64) -> Result<c_int, io::Error> {
    let mut attrs: perf_event_attr = perf_event_open_sys::bindings::perf_event_attr {
        size: std::mem::size_of::<sys::bindings::perf_event_attr>() as u32,
        type_: sys::bindings::PERF_TYPE_SOFTWARE,
        config: sys::bindings::PERF_COUNT_SW_CPU_CLOCK as u64,
        ..Default::default()
    };
    attrs.__bindgen_anon_1.sample_freq = sample_freq;
    attrs.set_disabled(1);
    attrs.set_freq(1);

    let ret = unsafe {
        sys::perf_event_open(
            &mut attrs, -1, /* pid */
            cpu, -1, /* group_fd */
            0,  /* flags */
        )
    } as c_int;

    if ret < 0 {
        return Err(io::Error::last_os_error());
    }

    Ok(ret)
}