Example to limit the cpu affinity

thread_cpu.c

#include <stdlib.h>
#include <stdatomic.h>
#define __USE_GNU 
#include <sched.h>
#include <pthread.h>

typedef struct {
    char name[16];
    int sleepTime;
} Node;

void _usleep(int);
void* generateSingleThread(void*);
void  printAndSleep(Node*);

atomic_int acnt;
int main(void) {
    cpu_set_t cmask;
    unsigned long len = sizeof(cmask);
    CPU_ZERO(&cmask);   /* 初始化 cmask */
    CPU_SET(0, &cmask); /* 指定第一個處理器 */
    /* 設定自己由指定的處理器執行 */
        
    if (sched_setaffinity(0, len, &cmask)) {
        printf("Could not set cpu affinity for current process.\n");
        exit(1);
    }   

    Node nodes[] = {{"One", 100000}, {"Two", 200000}, {"Three", 300000}};
    pthread_t thread[3];
    for (int i=0; i<3; ++i) {
        pthread_create(&thread[i], NULL, generateSingleThread, (void*) &nodes[i]);
    }   
    for (int i=0; i<3; ++i) pthread_join(thread[i],NULL);
    return 0;
}

void* generateSingleThread(void* nodes) {
    Node* node = (Node*)nodes;
    for (int i=0; i<1000; ++i) {
        while (acnt) sched_yield() ;
        atomic_fetch_add(&acnt, 1);
        printf("%dth Time: ", i);
        atomic_fetch_sub(&acnt, 1);
        printAndSleep(node);
    }
    pthread_exit(NULL);
}

void  printAndSleep(Node* node) {
    printf("%s\n", node->name);
    _usleep(node->sleepTime);
}
void _usleep(int micro)
{
    struct timespec req = {0};
    req.tv_sec = 0;
    req.tv_nsec = micro * 1000L;
    nanosleep(&req, (struct timespec *)NULL);
}