[Xenomai] Xenomai 3.0.5 - sigwaitinfo si_overrun wrong value

[Xenomai] Xenomai 3.0.5 - sigwaitinfo si_overrun wrong value

[Fazio Maurizio]

Hello,
I'm running an application using the xenomai 3.0.5...
I have a problem with the si_overrun field of the siginfo_t structure returned by the sigwaitinfo function.
I armed a timer with and interval of 1ms… every 3 timer ticks I execute a sleep of 1.5 ms… I expect an overrun in that cycle but no overrun occurs…
Why??

The following is the interested part of the source code:

timer_t timer1;
pthread_t thread;

void* print_time (void* args)
{
     struct timespec tp;
     char buffer [80];
     struct itimerspec new_value, old_value;
     struct sigevent sevent;
     sigset_t set;
     siginfo_t siginfo;
     int signum = SIGRTMIN;
     sevent.sigev_notify = SIGEV_THREAD_ID;
     sevent._sigev_un._tid = syscall(__NR_gettid);
     sevent.sigev_signo = signum;

     sigemptyset(&set);
     sigaddset(&set, signum);
     sigprocmask(SIG_BLOCK, &set, NULL);

     if (timer_create (CLOCK_REALTIME, &sevent, &timer1) == -1)
             perror ("timer_create");

     new_value.it_interval.tv_sec = 0;
     new_value.it_interval.tv_nsec = 1000000;
     new_value.it_value.tv_sec = 0;
     new_value.it_value.tv_nsec = 1000000;

     if (timer_settime (timer1, 0, &new_value, &old_value) == -1)
         perror ("timer_settime");

     unsigned int counter = 0;
     struct timespec lastTime;
     while(1){

         /* wait for signal */
         if (sigwaitinfo(&set, &siginfo) == -1) perror ("sigwait");

         if (clock_gettime (CLOCK_REALTIME, &tp) == -1)
             perror ("clock_gettime");

         struct timespec diffTime = timespec_sub(tp, lastTime);
         lastTime = tp;

         sprintf (buffer, "%ld s %ld ns - %ld s %ld ns overrun = %d\n",tp.tv_sec,
                 tp.tv_nsec, diffTime.tv_sec,diffTime.tv_nsec, siginfo.si_overrun);

         write (STDOUT_FILENO, buffer, strlen (buffer));
         if (counter % 3 == 0)
         {
               usleep(1500);
         }
         counter++;
     }
}

int main(int argc, char* argv[])
{
     pthread_create(&thread, NULL, print_time, NULL);

     pthread_join(thread, NULL);
     exit (EXIT_SUCCESS);
}

----------------------------
The following is the output:

1286 s 77432620 ns - 1285 s 77432491 ns overrun = 0
1286 s 78975557 ns - 0 s 1542937 ns overrun = 0
1286 s 79431008 ns - 0 s 455451 ns overrun = 0
1286 s 80430867 ns - 0 s 999859 ns overrun = 0
1286 s 81990548 ns - 0 s 1559681 ns overrun = 0
1286 s 82431705 ns - 0 s 441157 ns overrun = 0
1286 s 83434563 ns - 0 s 1002858 ns overrun = 0
1286 s 84999441 ns - 0 s 1564878 ns overrun = 0
And so on...

I expected one overrun every 3 ticks but no one occurs...
Someone can help me with this trouble??


Thanks in advance


Maurizio Fazio

Chief Technical Office / Aircraft Systems
Software Engineer



Leonardo S.p.A.
C.so Francia, 426 - Torino - 10146 - Italy
Tel. +39 011 756 3308 / 3761
cell. +39 328 3488070
maurizio.fazio@leonardocompany.com
www.leonardocompany.com

————————————————————————————————–——————
HELICOPTERS/AERONAUTICS/ELECTRONICS, DEFENCE & SECURITY SYSTEMS/SPACE
————————————————————————————————–——————



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Re: [Xenomai] Xenomai 3.0.5 - sigwaitinfo si_overrun wrong value

[Philippe Gerum]

On 10/26/2017 03:56 PM, Fazio Maurizio wrote:

[snip]

>          sprintf (buffer, "%ld s %ld ns - %ld s %ld ns overrun = %d\n",tp.tv_sec,
>                  tp.tv_nsec, diffTime.tv_sec,diffTime.tv_nsec, siginfo.si_overrun);
> 
>          write (STDOUT_FILENO, buffer, strlen (buffer));

Bad, will switch the caller to secondary mode.

>          if (counter % 3 == 0)
>          {
>                usleep(1500);

Ditto with 3.0.5.

>          }
>          counter++;
>      }
> }
> 

Excerpt from the timer_getoverrun() manpage:

"The timer overrun count is  the  number of additional timer expirations
that occurred between the time when the signal was generated and when it
was delivered or accepted."

So you need to delay for at least two intervals before receiving a
non-zero overrun count.

You may want to check this building your code over the plain glibc.
usleep(1500) gives no overruns, usleep(2000) gives 1, usleep(3000) gives
2 and so on.

-- 
Philippe.