Thanks for your answer. That's really great to have support so quickly. :)
> I got some difficulties to use either rt_alarm_wait or clock_nanosleep.
> It seems i haven't understood what's a "context that can sleep".
>
> First of all, what do we need to use clock_nanosleep ?
> Is it impossible to use this function in the main thread ?
Xenomai clock_nanosleep, nanosleep or rt_alarm_wait services are
reserved to Xenomai real-time threads, and will return an error of EPERM
otherwise.
Ok. So the thread "main" is not a Xenomai real-time, right ?
If you want to obtain a Xenomai real-time thread using the posix skin
you have to make it use the SCHED_FIFO policy, either by creating it
with the pthread_create service, specifying non null creation attributes
or by changing the scheduling policy of an existing thread with
the pthread_setschedparam service.
Is it possible to apply those methods to the thread "main" ?
If you want to obtain a Xenomai real-time thread using the native skin,
you may create it with the rt_task_create service or turn an existing
thread into a real-time thread with the rt_task_shadow service.
> (...)
> ret = nanosleep(&tp, &rmtp);
> switch (errno) {
> (...)
errno value is only meaningful if nanosleep returns -1. In particular it
is not garanteed to be zero if nanosleep did not fail.
Mmm... Copy-Paste mistake.
There's still my sched_setscheduler enigma.
Why the following program need the commented line to run perfectly, and
why nanosleep failed without those lines ?
#include <time.h>
#include <stdio.h>
#include <errno.h>
#include <pthread.h>
#define NANOCOEF 0.000000001
double getfloattime(const struct timespec *tp){
return tp->tv_sec + tp->tv_nsec * NANOCOEF;
}
int setfloattime(struct timespec *tp, double val) {
tp->tv_sec = (time_t)val;
tp->tv_nsec = (long) ( ( val - (double)(tp->tv_sec) ) / NANOCOEF );
return 0;
}
void * task(void * p)
{
struct timespec tp, rmtp;
int ret;
clock_gettime( CLOCK_REALTIME, &tp);
printf("start time : %lf\n", getfloattime( &tp ));
setfloattime(&tp, 1.0);
ret = nanosleep(&tp, &rmtp);
if(ret)
{
switch (errno) {
case 0: printf("clock_nanosleep ok\n");
break;
case EPERM: printf("the caller context is invalid\n");
return NULL;
case ENOTSUP: printf("the specified clock is unsupported\n");
return NULL;
case EINVAL: printf("the specified wakeup time is invalid\n");
return NULL;
case EINTR: printf("this service was interrupted by a
signal\n");
return NULL;
}
}
else
{
printf("nanosleep OK\n");
}
clock_gettime( CLOCK_REALTIME, &tp);
printf("stop time : %lf\n", getfloattime( &tp ));
return NULL;
}
int main(int argc, char *argv[])
{
pthread_t th;
pthread_attr_t th_attr;
struct sched_param mysched;
/*
mysched.sched_priority = sched_get_priority_max(SCHED_FIFO) - 1;
if( sched_setscheduler( 0, SCHED_FIFO, &mysched ) == -1 ) {
perror("sched_setscheduler");
}*/
if(pthread_attr_init(&th_attr))
perror("pthead_attr_init");
if (pthread_attr_setschedpolicy(&th_attr, SCHED_FIFO))
perror("pthread_attr_setschedpolicy");
if (pthread_create(&th, &th_attr, task, NULL))
perror("pthread_create");;
if(pthread_join(th, NULL))
perror("pthread_join");
return 0;
}
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