linux线程的优先级设置

转自：http://blog.csdn.net/lanseshenhua/article/details/5524797

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <signal.h>
#include    <string.h>
void * thr_fun(void *arg)
{
 int policy, ret;
 struct sched_param param;
 //获取线程调度参数
 ret = pthread_getschedparam(pthread_self(), &policy, &param);
 if(ret!=0)
 {
  printf("pthread_getschedparam %s/n", strerror(ret) );
  exit(1);
 }
 if (policy == SCHED_FIFO)
 {
  printf("policy:SCHED_FIFO/n");
 }
 else if (policy == SCHED_OTHER)
 {
  printf("policy:SCHED_OTHER/n");
 }
 else if (policy == SCHED_RR)
 {
  printf("policy:SCHED_RR/n");
 }
 printf("param:%d/n", param.sched_priority); 
 long long i;
 while (1) {
  i++;
  i *= 2;
 }
 pthread_exit(NULL); 
}
int main(void)
{
 int ret;
 pthread_t tid;
 pthread_attr_t attr;
 int policy, inher;
 struct sched_param param;
 
 //初始化线程属性
 pthread_attr_init(&attr);
 //获取继承的调度策略
 ret = pthread_attr_getinheritsched(&attr, &inher);
 if (ret!=0)
 {
  printf("pthread_attr_getinheritsched/n%s/n", strerror(ret));
  exit(1);
 }
 //
 if (inher == PTHREAD_EXPLICIT_SCHED)
 {
  printf("PTHREAD_EXPLICIT_SCHED/n");
 }
    else if (inher == PTHREAD_INHERIT_SCHED)
 { 
  printf("PTHREAD_INHERIT_SCHED/n");
  inher = PTHREAD_EXPLICIT_SCHED;
 }
 //设置继承的调度策略
 //必需设置inher的属性为 PTHREAD_EXPLICIT_SCHED，否则设置线程的优先级会被忽略
 ret = pthread_attr_setinheritsched(&attr, inher);
 if (ret!=0)
 {
  printf("pthread_attr_setinheritsched/n%s/n", strerror(ret));
  exit(1);
 }
 
 policy = SCHED_FIFO;//在Ubuntu9.10上需要root权限
 //设置线程调度策略
 ret = pthread_attr_setschedpolicy(&attr, policy);
 if (ret!=0)
 {
  printf(" pthread_attr_setschedpolicy/n%s/n", strerror(ret));
  exit(1);
 }
 param.sched_priority = 3;
 //设置调度参数
 ret = pthread_attr_setschedparam(&attr, &param);
 if (ret!=0)
 {
  printf(" pthread_attr_setschedparam/n%s/n", strerror(ret));
  exit(1);
 }
 //创建线程
 ret = pthread_create(&tid, &attr, thr_fun, NULL);
 if (ret!=0)
 {
  printf("pthread_create/n%s/n", strerror(ret));
  exit(1);
 }
 while (1) {
  printf("hello world/n");
 }
 pthread_join(tid, NULL);
 pthread_exit(NULL);
}