linux线程优先级设置

1、Linux线程优先级设置： 首先，可以通过以下两个函数来获得线程可以设置的最高和最低优先级，函数中的策略即上述三种策略的宏定义：　　int sched_get_priority_max(int policy); 　　int sched_get_priority_min(int policy);

2、注意：SCHED_OTHER 是不支持优先级使用的，而 SCHED_FIFO 和 SCHED_RR 支持优先级的使用，他们分别为1和99，数值越大优先级越高。 设置和获取优先级通过以下两个函数：int pthread_attr_setschedparam(pthread_attr_t *attr, const struct sched_param *param);int pthread_attr_getschedparam(const pthread_attr_t *attr, struct sched_param *param); param.sched_priority = 51; //设置优先级

3、系统创建线程时，默认的线程是 SCHED_OTHER。所以如果我们要改变线程的调度策略的话，可以通过下面的这个函数实现。int pthread_attr_setschedpolicy(pthread_attr_t *attr, int policy); 上面的param使用了下面的这个数据结构：struct sched_param { int __sched_priority; // 所要设定的线程优先级};

4、我们可以通过下面的测试程序来说明，我们自己使用的系统的支持的优先级：#include <stdio.h>#include <pthread.h>#include <sched.h>#include <assert.h>static int api_get_thread_policy (pthread_attr_t *attr){ int policy; int rs = pthread_attr_getschedpolicy (attr, &policy); assert (rs == 0); switch (policy) { case SCHED_FIFO: printf ("policy = SCHED_FIFO\n"); break; case SCHED_RR: printf ("policy = SCHED_RR"); break; case SCHED_OTHER: printf ("policy = SCHED_OTHER\n"); break; default: printf ("policy = UNKNOWN\n"); break; } return policy;}static void api_show_thread_priority (pthread_attr_t *attr,int policy){ int priority = sched_get_priority_max (policy); assert (priority != -1); printf ("max_priority = %d\n", priority); priority = sched_get_priority_min (policy); assert (priority != -1); printf ("min_priority = %d\n", priority);}static int api_get_thread_priority (pthread_attr_t *attr){ struct sched_param param; int rs = pthread_attr_getschedparam (attr, &param); assert (rs == 0); printf ("priority = %d\n", param.__sched_priority); return param.__sched_priority;}static void api_set_thread_policy (pthread_attr_t *attr,int policy){ int rs = pthread_attr_setschedpolicy (attr, policy); assert (rs == 0); api_get_thread_policy (attr);} int main(void){ pthread_attr_t attr; // 线程属性 struct sched_param sched; // 调度策略 int rs; /* * 对线程属性初始化 * 初始化完成以后，pthread_attr_t 结构所包含的结构体 * 就是操作系统实现支持的所有线程属性的默认值 */ rs = pthread_attr_init (&attr); assert (rs == 0); // 如果 rs 不等于 0，程序 abort() 退出 /* 获得当前调度策略 */ int policy = api_get_thread_policy (&attr); /* 显示当前调度策略的线程优先级范围 */ printf ("Show current configuration of priority\n"); api_show_thread_priority(&attr, policy); /* 获取 SCHED_FIFO 策略下的线程优先级范围 */ printf ("show SCHED_FIFO of priority\n"); api_show_thread_priority(&attr, SCHED_FIFO); /* 获取 SCHED_RR 策略下的线程优先级范围 */ printf ("show SCHED_RR of priority\n"); api_show_thread_priority(&attr, SCHED_RR); /* 显示当前线程的优先级 */ printf ("show priority of current thread\n"); int priority = api_get_thread_priority (&attr); /* 手动设置调度策略 */ printf ("Set thread policy\n"); printf ("set SCHED_FIFO policy\n"); api_set_thread_policy(&attr, SCHED_FIFO); printf ("set SCHED_RR policy\n"); api_set_thread_policy(&attr, SCHED_RR); /* 还原之前的策略 */ printf ("Restore current policy\n"); api_set_thread_policy (&attr, policy); /* * 反初始化 pthread_attr_t 结构 * 如果 pthread_attr_init 的实现对属性对象的内存空间是动态分配的， * phread_attr_destory 就会释放该内存空间 */ rs = pthread_attr_destroy (&attr); assert (rs == 0); return 0;}

5、下面是测试程序的运行结果：policy=SCHED_OTHERShow current configuration of prioritymax_priority=0min_priority=0show SCHED_FIFO of prioritymax_priority=99min_priority=1show SCHED_RR of prioritymax_priority=99min_priority=1show priority of current threadpriority=0Set thread policyset SCHED_FIFO policypolicy= SCHED_FIFOset SCHED_RR policypolicy= SCHED_RRRestore current policypolicy=SCHED_OTHER