Preempt Rt例程

原文:https://wiki.linuxfoundation.org/realtime/documentation/howto/applications/application_base

 /*$gcc -o thisfile thisfile.c -lpthread -lrt -Wall
   $sudo ./thisfile
 */
/*                                                                  
 * POSIX Real Time Example
 * using a single pthread as RT thread
 */
#include <limits.h>
#include <pthread.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>

void *thread_func(void *data)
{
        /* Do RT specific stuff here */
        return NULL;
}

int main(int argc, char* argv[])
{
        struct sched_param param;
        pthread_attr_t attr;
        pthread_t thread;
        int ret;

        /* Lock memory */
        if(mlockall(MCL_CURRENT|MCL_FUTURE) == -1) {
                printf("mlockall failed: %m\n");
                exit(-2);
        }

        /* Initialize pthread attributes (default values) */
        ret = pthread_attr_init(&attr);
        if (ret) {
                printf("init pthread attributes failed\n");
                goto out;
        }

        /* Set a specific stack size  */
        ret = pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN);
        if (ret) {
            printf("pthread setstacksize failed\n");
            goto out;
        }

        /* Set scheduler policy and priority of pthread */
        ret = pthread_attr_setschedpolicy(&attr, SCHED_FIFO);
        if (ret) {
                printf("pthread setschedpolicy failed\n");
                goto out;
        }
        param.sched_priority = 80;
        ret = pthread_attr_setschedparam(&attr, &param);
        if (ret) {
                printf("pthread setschedparam failed\n");
                goto out;
        }
        /* Use scheduling parameters of attr */
        ret = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
        if (ret) {
                printf("pthread setinheritsched failed\n");
                goto out;
        }

        /* Create a pthread with specified attributes */
        ret = pthread_create(&thread, &attr, thread_func, NULL);
        if (ret) {
                printf("create pthread failed\n");
                goto out;
        }

        /* Join the thread and wait until it is done */
        ret = pthread_join(thread, NULL);
        if (ret)
                printf("join pthread failed: %m\n");

out:
        return ret;
}