1 use nix::sched::{sched_getaffinity, sched_getcpu, sched_setaffinity, CpuSet};
2 use nix::unistd::Pid;
3 
4 #[test]
test_sched_affinity()5 fn test_sched_affinity() {
6     // If pid is zero, then the mask of the calling process is returned.
7     let initial_affinity = sched_getaffinity(Pid::from_raw(0)).unwrap();
8     let mut at_least_one_cpu = false;
9     let mut last_valid_cpu = 0;
10     for field in 0..CpuSet::count() {
11         if initial_affinity.is_set(field).unwrap() {
12             at_least_one_cpu = true;
13             last_valid_cpu = field;
14         }
15     }
16     assert!(at_least_one_cpu);
17 
18     // Now restrict the running CPU
19     let mut new_affinity = CpuSet::new();
20     new_affinity.set(last_valid_cpu).unwrap();
21     sched_setaffinity(Pid::from_raw(0), &new_affinity).unwrap();
22 
23     // And now re-check the affinity which should be only the one we set.
24     let updated_affinity = sched_getaffinity(Pid::from_raw(0)).unwrap();
25     for field in 0..CpuSet::count() {
26         // Should be set only for the CPU we set previously
27         assert_eq!(
28             updated_affinity.is_set(field).unwrap(),
29             field == last_valid_cpu
30         )
31     }
32 
33     // Now check that we're also currently running on the CPU in question.
34     let cur_cpu = sched_getcpu().unwrap();
35     assert_eq!(cur_cpu, last_valid_cpu);
36 
37     // Finally, reset the initial CPU set
38     sched_setaffinity(Pid::from_raw(0), &initial_affinity).unwrap();
39 }
40