SIS in "real time"

[Gedare Bloom]

On Fri, Apr 9, 2021 at 11:45 AM Heinz Junkes <junkes at fhi-berlin.mpg.de> wrote:
>
> Jiri, Joel, thanks for your answers.
>
> @Joel: I was wondering that rtems-examples in psx_example_3 does not wait 3 seconds.
>
> I made a curious observation:
>
> in the original code:
>
>    clock_gettime( CLOCK_REALTIME, &timeout );
>    timeout.tv_sec += 3;
>    timeout.tv_nsec = 0;
>    printf("The task is coming to enter in a timed wait\n");
>    pthread_cond_timedwait(&cond, &mutex, &timeout);
>
>
> I then inserted some printfs and found that the "3" is added to the nsec’s.
>
> Then I added the rtems-timespec-helpers routines, but get the same behavior:
>
>
> void * print_hello(void * arg)
> {
>   struct timespec now, timeout;
>   rtems_timespec_set(&timeout, 3, 0);
>
>   printf("<child>: Hello World! task with max priority \n");
>   clock_gettime( CLOCK_REALTIME, &now );
> printf("now tv_sec = %d, tv_nsec = %d\n", now.tv_sec, now.tv_nsec);
>   rtems_timespec_add_to(&timeout, &now);
> printf("timeout tv_sec = %d, tv_nsec = %d\n", timeout.tv_sec, timeout.tv_nsec);

Please try with the appropriate type sizes and report back what you find.

tv_sec is of type time_t
tv_nsec is of type long

%d will only take 32b of those values, so you get some kind of garbage
(that can depend on endianness)

>   printf("The task is coming to enter in a timed wait\n");
>   pthread_cond_timedwait(&cond, &mutex, &timeout);
>   printf("The task is coming out from the timed wait \n");
>   return NULL;
> }
>
> program output:
>
> <main> Enter in the main
> Creating first task
> <child>: Hello World! task with max priority
> now tv_sec = 4766459, tv_nsec = 567993600
> timeout tv_sec = 4766459, tv_nsec = 567993603
> The task is coming to enter in a timed wait
> The task is coming out from the timed wait
> First Task created
> Creating second task
>  <child>: Hello World! Task with lowest priority Second task created
> <main> Out of the main
>
> If I now swap the arguments in the set-function , i.e. instead of
>  rtems_timespec_set(&timeout, 3, 0);
>
>  rtems_timespec_set(&timeout, 0, 3);
>
> it looks as it should
>
> <child>: Hello World! task with max priority
> now tv_sec = 10766729, tv_nsec = 567993600
> timeout tv_sec = 10766732, tv_nsec = 567993600
> The task is coming to enter in a timed wait
> The task is coming out from the timed wait
> First Task created
> Creating second task
>  <child>: Hello World! Task with lowest priority Second task created
> <main> Out of the main
>
> But still no timed wait  recognizable :-(
>
> Heinz
>
>
>
> _______________________________________________
> users mailing list
> users at rtems.org
> http://lists.rtems.org/mailman/listinfo/users