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Implement sched::sched_getaffinity()
sched_getaffinity(2) get a process's CPU affinity mask
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use nix::sched::{sched_getaffinity, sched_setaffinity, CpuSet}; | ||
use nix::unistd::Pid; | ||
use std::mem; | ||
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#[test] | ||
fn test_sched_affinity() { | ||
// If pid is zero, then the mask of the calling process is returned. | ||
let initial_affinity = sched_getaffinity(Pid::from_raw(0)).unwrap(); | ||
let mut at_least_one_cpu = false; | ||
let mut last_valid_cpu = 0; | ||
for field in 0..(8 * mem::size_of::<libc::cpu_set_t>()) { | ||
if initial_affinity.is_set(field).unwrap() { | ||
at_least_one_cpu = true; | ||
last_valid_cpu = field; | ||
} | ||
} | ||
assert!(at_least_one_cpu); | ||
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// Now restrict the running CPU | ||
let mut new_affinity = CpuSet::new(); | ||
new_affinity.set(last_valid_cpu).unwrap(); | ||
sched_setaffinity(Pid::from_raw(0), &new_affinity).unwrap(); | ||
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// And now re-check the affinity which should be only the one we set. | ||
let updated_affinity = sched_getaffinity(Pid::from_raw(0)).unwrap(); | ||
for field in 0..(8 * mem::size_of::<libc::cpu_set_t>()) { | ||
// Should be set only for the CPU we set previously | ||
assert_eq!(updated_affinity.is_set(field).unwrap(), field==last_valid_cpu) | ||
} | ||
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// Finally, reset the initial CPU set | ||
sched_setaffinity(Pid::from_raw(0), &initial_affinity).unwrap(); | ||
} |