Re: [Xenomai-help] Timer problemm with 2.2.4 release

[Jan Kiszka <jan.kiszka@domain.hid>]

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Stephan Zimmermann wrote:
> Hello list,
> I recently switched from 2.2.0 on Kernel 2.6.17.6 to more actual 2.2.4  on 
> Kernel 2.6.17.14.
> After upgrading my periodic tasks won't work at all (task_wait and 
> set_periodic functions return errors). I wrote a little testprogram to verify 
> it's not a problem with my Software. The code runs fine on my Notebook, still 
> under 2.2.0/2.6.17.6, but won't work on my Desktop (AMD X2 / VIA K8T800) with 
> the all-new Kernel/Xenomai installation. Maybe there is some config-thing i 
> have overseen?
> 
> #include <iostream>
> #include <sys/mman.h>
> 
> #include "native/task.h"
> #include "native/timer.h"
> 
> RT_TASK maintask;
> 
> int main(void){
> 	std::cout << "xenomai 2.2.4 timer-test" << std::endl;
> 	mlockall(MCL_CURRENT | MCL_FUTURE);
> 	
> 	int err;
> 	unsigned long overrun = 0; 
> 	
> 	err = rt_task_shadow (&maintask,"maintask",10,0);
> 	std::cout << "task shadow:" << err << std::endl;
> 	
> 	err = rt_timer_set_mode(1000000);
> 	std::cout << "timer set mode:" << err << std::endl;
> 	
> 	err = rt_task_sleep(1000);
> 	std::cout << "task sleep:" << err << std::endl;
> 	
> 	err = rt_task_set_periodic(NULL,TM_NOW,1000);  
> 	std::cout << "task set periodic:" << err << std::endl;
> 	
> 	for(int i  = 0; i < 3; i++){
> 		err = rt_task_wait_period(&overrun);
> 		std::cout << "task wait period:" << err << " overrunns:" << overrun << 
> std::endl;
> 	}
> 	
> 	return 0;
> }
> 
> Output on my Workstation:
> ----------------------------------------------
> xenomai 2.2.4 timer-test
> task shadow:0
> timer set mode:0
> task sleep:0
> task set periodic:-22
> task wait period:-11 overrunns:0
> task wait period:-11 overrunns:0
> task wait period:-11 overrunns:0
> 
> Output on my Notebook:
> ----------------------------------------------
> xenomai 2.2.4 timer-test

I guess this is a typo (2.2.0?).

> task shadow:0
> timer set mode:0
> task sleep:0
> task set periodic:0
> task wait period:0 overrunns:0
> task wait period:0 overrunns:0
> task wait period:0 overrunns:0
> 

Looks like we have a bug here:

http://www.rts.uni-hannover.de/xenomai/lxr/source/ksrc/nucleus/pod.c#L3408

That new LART check doesn't consider the periodic mode where period does
not have the same unit as nkschedlat. Something like this might be
needed (quick hack alarm!):

--- ksrc/nucleus/pod.c  (revision 1747)
+++ ksrc/nucleus/pod.c  (working copy)
@@ -3413,7 +3413,7 @@ int xnpod_set_thread_periodic(xnthread_t
                        xntimer_stop(&thread->ptimer);

                goto unlock_and_exit;
-       } else if (period < nkschedlat) {
+       } else if (nkpod->tickvalue == 1 && period < nkschedlat) {
                /* LART: detect periods which are shorter than the
                 * intrinsic latency figure; this must be a joke... */
                err = -EINVAL;

Jan


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