Crate preempt_rt

Rust friendly bindings to the scheduler related functionality in libc.

The sched module contains types and lightweight wrappers around libc functions. For example:

use preempt_rt::sched;
use preempt_rt::sched::{Pid, Scheduler, SchedulerParams};
let sched = sched::get_scheduler(Pid::current_thread()).unwrap();
sched::set_scheduler(Pid::current_thread(), Scheduler::SCHED_FIFO, SchedulerParams {
    priority: 80
}).expect("failed to set scheduler");

The thread module has wrappers around thread::spawn for creating threads with a given scheduler and priority.

use preempt_rt::sched::{RtResult, Scheduler};
use preempt_rt::thread;
thread::spawn(Scheduler::SCHED_FIFO, 80, move || {
    println!("this code is running on a thread with fifo scheduler & priority of 80");
});
// setting scheduler requires linux + preempt_rt kernel + appropriate permissions so may fail
thread::try_spawn(Scheduler::SCHED_FIFO, 80, move |sched_result| {
    match sched_result {
        Ok(()) => {}
        Err(e) => eprintln!("failed to set scheduler: {e}")
    }
});

Only SCHED_FIFO and SCHED_RR are meaningfully supported at the moment - SCHED_DEADLINE requires additional parameters to be set, but on most platforms the Rust libc bindings don’t allow setting the additional attributes necessary to make this work, and the libc::sched_setattr function has to be used to change the values rather than libc::sched_setscheduler.

This crate has one feature, enabled by default - non-linux-stubs adds a stub method for preempt_rt::thread::try_spawn that compiles on macOS (but does not attempt to set a scheduler). This is useful for building/running tests on non-linux platforms.

Modules

sched

thread