QNX 线程调度策略优先级时钟频率同步

最新推荐文章于 2025-05-14 12:15:30 发布

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最新推荐文章于 2025-05-14 12:15:30 发布

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原文链接：http://www.cnblogs.com/splovecyk/p/4502388.html

本文通过一个具体的C语言程序示例介绍了多线程环境下使用pthread_barrier进行同步的方法。该程序创建了两个工作线程和一个主线程，并通过屏障对象实现三个线程之间的同步。每个线程还展示了如何设置不同的优先级并打印出开始和完成的时间。

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/*
* barrier1.c
*/

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <time.h>
#include <pthread.h>
#include <sys/neutrino.h>
#include <timer.h>

pthread_barrier_t barrier; // barrier synchronization object

void *thread1 (void *not_used)
{

int policy;
struct sched_param param;
pthread_getschedparam(pthread_self(),&policy,&param);
if(policy == SCHED_OTHER)
printf("SCHED_OTHER 1 \n");
if(policy == SCHED_RR);
printf("SCHED_RR 1 \n");
if(policy==SCHED_FIFO)
printf("SCHED_FIFO 1 \n");
if(policy==SCHED_SPORADIC)
printf("SCHED_SPARODIC 1 \n");

setprio(0, 11); //设置线程优先级越大优先级越高 0 代表当前进程
printf("thread1 priority is %d\n",getprio(0));

time_t now;

time (&now);
printf ("thread1 starting at %s", ctime (&now));

// do the computation
// let's just do a sleep here...
while(1)
{
delay (100);
pthread_barrier_wait (&barrier);
// after this point, all three threads have completed.
time (&now);
printf ("barrier in thread1() done at %s", ctime (&now));
}
}

void *thread2 (void *not_used)
{
//查看线程的调度策略默认为轮询
int policy;
struct sched_param param;
pthread_getschedparam(pthread_self(),&policy,&param);
if(policy == SCHED_OTHER)
printf("SCHED_OTHER 2 \n");
if(policy == SCHED_RR);
printf("SCHED_RR 2 \n");
if(policy==SCHED_FIFO)
printf("SCHED_FIFO 2 \n");
if(policy==SCHED_SPORADIC)
printf("SCHED_SPARODIC 1 \n");

setprio(0, 10); //设置线程优先级越大优先级越高 0 代表当前进程
printf("thread2 priority is %d\n",getprio(0));

time_t now;

time (&now);
printf ("thread2 starting at %s", ctime (&now));

// do the computation
// let's just do a sleep here...
while(1)
{
delay (200);
pthread_barrier_wait (&barrier);
// after this point, all three threads have completed.
time (&now);
printf ("barrier in thread2() done at %s", ctime (&now));
}
}

int main () // ignore arguments
{

pthread_t threadID1,threadID2;

setprio(0, 12); //设置线程优先级越大优先级越高 0 代表当前进程
printf("Main priority is %d\n",getprio(0));
//CPU 时钟频率
struct _clockperiod timep;
timep.nsec = 10*1000;
timep.fract = 0;
int ErrCode = 0;
ErrCode = ClockPeriod(CLOCK_REALTIME, &timep, NULL, 0);
if(ErrCode!=0)
{
printf( "Error: %s\n", strerror(ErrCode));
}
/****************************************/
int ret = -1;
int timer_interrupt_id = -1;
ret = InitializeTimerInterrupt(0, 300, &timer_interrupt_id); //设置时钟中断，10ms
/*****************************************/
time_t now;

// create a barrier object with a count of 3
pthread_barrier_init (&barrier, NULL, 3);

// start up two threads, thread1 and thread2
pthread_create (&threadID1, 0, thread1, 0);
pthread_create (&threadID2, NULL, thread2, NULL);
// at this point, thread1 and thread2 are running

// now wait for completion
time (&now);
printf ("main() waiting for barrier at %s", ctime (&now));
while(1)
{
InterruptWait(0, NULL);
pthread_barrier_wait (&barrier);
// after this point, all three threads have completed.
time (&now);
printf ("barrier in main() done at %s", ctime (&now));
}
pthread_exit( NULL );
return (EXIT_SUCCESS);
}

转载于:https://www.cnblogs.com/splovecyk/p/4502388.html