按比例吃CPU

前几天测试软件在多核上的性能，需要按照比例吃各个CPU，查了查资料，撸了下面一小段代码；

#include <unistd.h>    
#include <stdlib.h> 
#include <stdio.h>
#include <time.h>

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

//CPU ID号
#define CPU_0 0x0
#define CPU_1 0x01
#define CPU_2 0x02
#define CPU_3 0x03

//总时间和运行时间
#define FULL_TIME 100
#define RUN_TIME 80

//时钟HZ数
static clock_t clktck;

//用户参数输入的吃CPU百分比
static int eat_cpu_percent;

//线程绑定CPU
int attach_cpu(int cpu_index)
{
    int cpu_num = sysconf(_SC_NPROCESSORS_CONF);
    if (cpu_index < 0 || cpu_index >= cpu_num) 
    {
        perror("cpu index ERROR!
");
        return -1;
    }

    cpu_set_t mask;
    CPU_ZERO(&mask);
    CPU_SET(cpu_index, &mask);

    if (pthread_setaffinity_np(pthread_self(), sizeof(mask), &mask) < 0)
    {
        perror("set affinity np ERROR!
");
        return -1;
    }

    return 0;
}

//吃CPU线程
void *thread_task(void *param)
{
    int *cpuid = (int *)param;
    if (attach_cpu(*cpuid) < 0)
    {
        pthread_exit(NULL);
    }
    
    clock_t time_start;
    clock_t fulltime = FULL_TIME;
    clock_t runtime = eat_cpu_percent;
    while(1)
    {
        time_start = times(NULL);
        while((times(NULL) - time_start) < runtime);
        usleep((fulltime-runtime) * 1000 * 1000 / clktck);
    }
    
    pthread_exit(NULL);
}


int main(int argc, char *argv[])
{
    if (argc < 2)
    {
        printf("Please run with 0-100! Example：./eat_cpu 80
");
        return -1;
    }
    
    eat_cpu_percent = (atoi)(argv[1]);
    if (eat_cpu_percent < 0 || eat_cpu_percent > 100)
    {
        printf("eat cpu percent must in range:0-100!
");
        return -1;
    }
    
    int ret = 0;
    
    clktck = sysconf(_SC_CLK_TCK);
    
    pthread_t t0;
    int cpuid0 = CPU_0;
    if (pthread_create(&t0, NULL, thread_task, &cpuid0) < 0) 
    {
        perror("create thread 0 ERROR!
");
        ret = -1;
        goto _OUT;
    }
    
    pthread_t t1;
    int cpuid1 = CPU_1;
    if (pthread_create(&t1, NULL, thread_task, &cpuid1) < 0) 
    {
        perror("create thread 1 ERROR!
");
        ret = -1;
        goto _CANCEL_0;
    }
    
    pthread_t t2;
    int cpuid2 = CPU_2;
    if (pthread_create(&t2, NULL, thread_task, &cpuid2) < 0) 
    {
        perror("create thread 2 ERROR!
");
        ret = -1;
        goto _CANCEL_1;
    }
    
    pthread_t t3;
    int cpuid3 = CPU_3;
    if (pthread_create(&t3, NULL, thread_task, &cpuid3) < 0) 
    {
        perror("create thread 3 ERROR!
");
        ret = -1;
        goto _CANCEL_2;
    }
    
    //直接停这里好了
    while(1)
    {
        sleep(3600);
    }
    
_CANCEL_3:
    pthread_cancel(t3);
    pthread_join(t3, NULL);

_CANCEL_2:
    pthread_cancel(t2);
    pthread_join(t2, NULL);
    
_CANCEL_1:
    pthread_cancel(t1);
    pthread_join(t1, NULL);
    
_CANCEL_0:
    pthread_cancel(t0);
    pthread_join(t0, NULL);
    
_OUT:
    return ret;
}