Can't set the schedual parameter of threads in linux

[Jaap-Jan Boor]

yang,

Are you running your application as root? Also, try to get/set
the pthread schedule parameters in the pthread context itself.

Jaap-Jan

On Mar 11, 2004, at 2:06, yang wrote:

>
> Hello,
>     I encounter a problem when I transplant application.
>     There is no effect to the pthread when I call
> pthread_setschedparam() function in test program,  and it's policy and
> priority are stilll zero, not what I expected, after call
> pthread_getschedparam(). The codes  is as the follow:
>
> #include <sched.h>
> #include <pthread.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <sys/types.h>
> #include <linux/ipc.h>
> #include <linux/msg.h>
> #include <errno.h>
> #include <stddef.h>
> #include <string.h>
>
> void * func()
> {
>         while (1);
>     return;
> }
>
> int main()
> {
>     pthread_attr_t tattr;
>     pthread_t tid;
>     int policy;
>     int ret;
>     int newprio = 20;
>     struct sched_param param;
>
>     ret = pthread_attr_init (&tattr);
>     if (ret != 0)
>     {
>         printf("Error in init: %s\n", strerror(errno));
>     }
>
>     ret = pthread_attr_getschedparam (&tattr, &param);
>     if (ret != 0)
>     {
>         printf("Error in get after init: %s\n", strerror(errno));
>     }
>     ret = pthread_attr_setdetachstate(&tattr, PTHREAD_CREATE_DETACHED);
>    if (ret != 0)
>     {
>         printf("Error in setdea: %s\n", strerror(errno));
>     }
>     ret = pthread_attr_setschedpolicy(&tattr, SCHED_RR);
>     if (ret != 0)
>     {
>         printf("Error in setpolicy: %s\n", strerror(errno));
>     }
>
>     param.sched_priority = newprio;
>     ret = pthread_attr_setschedparam (&tattr, &param);
>     if (ret != 0)
>     {
>         printf("Error in set: %s\n", strerror(errno));
>     }
>
>     ret = pthread_create (&tid, &tattr, (int*) func, NULL);
>     if (ret != 0)
>     {
>         printf("Error in create: %s\n", strerror(errno));
>     }
>
>     param.sched_priority = -1;
>     ret = pthread_getschedparam (tid, &policy, &param);
>     if (ret != 0)
>     {
>         printf("Error in get after create: %d %s\n", ret,
> strerror(errno));
>     }
>
>     printf("policy: %d\tpriority: %d\n", policy, param.sched_priority);
>
>     return 0;
>
> }
>
>     The output is :
>     policy: 0    priority: 0
>
>     Would you like to tell me how to set the policy and priority to
> pthreads in Red Hat.? Thank you very much!
>     Best regards,
>                                      yang
>
>


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