漫话Redis源码之二十

这个函数用于在cpu list中设置cpu的affinity:

/* set current thread cpu affinity to cpu list, this function works like
 * taskset command (actually cpulist parsing logic reference to util-linux).
 * example of this function: "0,2,3", "0,2-3", "0-20:2". */
void setcpuaffinity(const char *cpulist) {
    const char *p, *q;
    char *end = NULL;
#ifdef __linux__
    cpu_set_t cpuset;
#endif
#if defined (__FreeBSD__) || defined(__DragonFly__)
    cpuset_t cpuset;
#endif
#ifdef __NetBSD__
    cpuset_t *cpuset;
#endif
 
    if (!cpulist)
        return;
 
#ifndef __NetBSD__
    CPU_ZERO(&cpuset);
#else
    cpuset = cpuset_create();
#endif
 
    q = cpulist;
    while (p = q, q = next_token(q, ','), p) {
        int a, b, s;
        const char *c1, *c2;
 
        if (next_num(p, &end, &a) != 0)
            return;
 
        b = a;
        s = 1;
        p = end;
 
        c1 = next_token(p, '-');
        c2 = next_token(p, ',');
 
        if (c1 != NULL && (c2 == NULL || c1 < c2)) {
            if (next_num(c1, &end, &b) != 0)
                return;
 
            c1 = end && *end ? next_token(end, ':') : NULL;
            if (c1 != NULL && (c2 == NULL || c1 < c2)) {
                if (next_num(c1, &end, &s) != 0)
                    return;
 
                if (s == 0)
                    return;
            }
        }
 
        if ((a > b))
            return;
 
        while (a <= b) {
#ifndef __NetBSD__
            CPU_SET(a, &cpuset);
#else
            cpuset_set(a, cpuset);
#endif
            a += s;
        }
    }
 
    if (end && *end)
        return;
 
#ifdef __linux__
    sched_setaffinity(0, sizeof(cpuset), &cpuset);
#endif
#ifdef __FreeBSD__
    cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, sizeof(cpuset), &cpuset);
#endif
#ifdef __DragonFly__
    pthread_setaffinity_np(pthread_self(), sizeof(cpuset), &cpuset);
#endif
#ifdef __NetBSD__
    pthread_setaffinity_np(pthread_self(), cpuset_size(cpuset), cpuset);
    cpuset_destroy(cpuset);
#endif
}
 
#endif /* USE_SETCPUAFFINITY */