Gosh, that was fun! A careful reading of the man page for
pthread_attr_setschedpolicy(3) says that SCHED_FIFO is only available to
"root" or super users. Your code works fine if you run as root. If
not, I think the thread is not created.
A STRONG suggestion: Put error tests and reports on EVERY call that can
generate them. Save a lot of time and embarrassment.
George
Malapati Narasimha Raju wrote:
>
> Hi all
>
> Im not really sure whether my question fits into this category or
> not. Since I did't find any relevent section for pthreads under Linux
> category Im sending my question to this list.
>
> My problem is related to pthreads scheduling. I wrote a small program using
> scheduling policy function. Seems the function "pthread_attr_setschedpolicy"
> is not working, because Im not able see printf statement's output on
> stdout(that means it is not entering the function func() at all). How ever
> If I remove the statement "pthread_attr_setschedpolicy(&custom_sched_attr,
> SCHED_FIFO);", I am able see the output on stdout.
>
> Can some body throw some light about this situation. As my project is fully
> depending on threads scheduling, early reply is highly appreciated.
>
> As I am not in the mailing list please send me an e-mail at
> "nraju_99@hotmail.com".
>
> Here is the code.
>
> #include <pthread.h>
> #include <sched.h>
> #include <stdio.h>
>
> void func(void)
> {
> printf("Im in Function func \n");
> }
>
> main()
> {
> pthread_t thread;
> pthread_attr_t custom_sched_attr;
> struct sched_param fifo_param;
>
> /* Initialize the attribute object */
> pthread_attr_init(&custom_sched_attr);
>
> /* Set the scheduling policy */
> pthread_attr_setschedpolicy(&custom_sched_attr, SCHED_FIFO);
>
> /* Set the scheduling priority */
> fifo_param.sched_priority = 99;
> pthread_attr_setschedparam(&custom_sched_attr, &fifo_param);
>
> /* Create a thread */
> pthread_create(&thread, &custom_sched_attr, (void *) func, NULL);
>
> /* Wait for thread completion */
> pthread_join(thread, NULL);
> }
>
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