linux-kernel-module-cheat/kernel_module/user/sched_getaffinity.c

/*
upstream; https://stackoverflow.com/questions/10490756/how-to-use-sched-getaffinity-and-sched-setaffinity-in-linux-from-c/50117787#50117787
*/

#define _GNU_SOURCE
#include <assert.h>
#include <sched.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

void print_affinity() {
    cpu_set_t mask;
    long nproc, i;

    if (sched_getaffinity(0, sizeof(cpu_set_t), &mask) == -1) {
        perror("sched_getaffinity");
        assert(false);
    } else {
        nproc = sysconf(_SC_NPROCESSORS_ONLN);
        printf("sched_getaffinity = ");
        for (i = 0; i < nproc; i++) {
            printf("%d ", CPU_ISSET(i, &mask));
        }
        printf("\n");
    }
}

int main(void) {
    cpu_set_t mask;

    print_affinity();
    printf("sched_getcpu = %d\n", sched_getcpu());
    CPU_ZERO(&mask);
    CPU_SET(0, &mask);
    if (sched_setaffinity(0, sizeof(cpu_set_t), &mask) == -1) {
        perror("sched_setaffinity");
        assert(false);
    }
    print_affinity();
    printf("sched_getcpu = %d\n", sched_getcpu());
    return EXIT_SUCCESS;
}