android cpu affinity

int omask = 0;
int nmask = 0xF0;

static void affinity() {
    int err;

    int syscallres = syscall(__NR_sched_getaffinity, gettid(), sizeof(omask), &omask);
    if (syscallres) {
        err = errno;
        LOGE("Error in the syscall getaffinity: omask=%d=0x%x err=%d=0x%x", omask, omask, err, err);
    }

    LOGE("before-get affinity success, tid = %d , mask = ", gettid(), omask);
    syscallres = syscall(__NR_sched_setaffinity, gettid(), sizeof(nmask), &nmask);
    if (syscallres) {
        err = errno;
        LOGE("Error in the syscall setaffinity: nmask=%d=0x%x err=%d=0x%x", nmask, nmask, err, err);
    }

    syscallres = syscall(__NR_sched_getaffinity, gettid(), sizeof(omask), &omask);
    if (syscallres) {
        err = errno;
        LOGE("Error in the syscall getaffinity: omask=%d=0x%x err=%d=0x%x", omask, omask, err, err);
    }

    LOGE("after-get affinity success, tid = %d , mask = ", gettid(), omask);
}