[Xenomai-help] Monitoring Xenomai scheduler switches

[Xenomai-help] Monitoring Xenomai scheduler switches

[Tschaeche IT-Services]

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Hi,

we started an application which monitors task switches
using Xenomai 2.5.3.

For monitoring primary domain switches we hooked
in our code by using rt_task_add_hook(T_HOOK_SWITCH)
(storing a timestamp and the Xenomai task ID in an array,
which is read later by user space appl from shared memory).

It seems, that our code is not called when Xenomai switches to the ROOT task.

We already had this issue with Xenomai 2.4.10
and solved it by applying the attached patch.

How can we catch these Xenomai scheduler events in 2.5.3?

What is the reason for filtering them out?

Best regards,

	Olli

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Index: xenomai-2.4.10/ksrc/nucleus/pod.c
===================================================================
--- xenomai-2.4.10.orig/ksrc/nucleus/pod.c	2009-08-11 15:53:55.000000000 +0200
+++ xenomai-2.4.10/ksrc/nucleus/pod.c	2010-01-27 12:41:05.000000000 +0100
@@ -2561,7 +2561,7 @@
 		nkpod->schedhook(runthread, XNRUNNING);
 #endif /* __XENO_SIM__ */
 
-	if (!emptyq_p(&nkpod->tswitchq) && !xnthread_test_state(runthread, XNROOT)) {
+	if (!emptyq_p(&nkpod->tswitchq)) {
 		trace_mark(xn_nucleus, thread_callout,
 			   "thread %p thread_name %s hook %s",
 			   runthread, xnthread_name(runthread), "SWITCH");

Re: [Xenomai-help] Monitoring Xenomai scheduler switches

[Andreas Glatz]

Hi,

> 
> we started an application which monitors task switches
> using Xenomai 2.5.3.
> 
> For monitoring primary domain switches we hooked
> in our code by using rt_task_add_hook(T_HOOK_SWITCH)
> (storing a timestamp and the Xenomai task ID in an array,
> which is read later by user space appl from shared memory).
> 

This is not related to your actual question: 

Do you want to monitor task switches for debugging or is it part of your application? If for debugging, have you ever used lttng? I know it takes a while to install it but it's quite reliable and can give you much more than the info when a certain task switch occured.

Regards, Andreas

Re: [Xenomai-help] Monitoring Xenomai scheduler switches

[Gilles Chanteperdrix]

Tschaeche IT-Services wrote:
> Hi,
> 
> we started an application which monitors task switches
> using Xenomai 2.5.3.
> 
> For monitoring primary domain switches we hooked
> in our code by using rt_task_add_hook(T_HOOK_SWITCH)
> (storing a timestamp and the Xenomai task ID in an array,
> which is read later by user space appl from shared memory).
> 
> It seems, that our code is not called when Xenomai switches to the ROOT task.
> 
> We already had this issue with Xenomai 2.4.10
> and solved it by applying the attached patch.
> 
> How can we catch these Xenomai scheduler events in 2.5.3?
> 
> What is the reason for filtering them out?

The nucleus switch hook service was created to implement the equivalent
service provided by RTOSes such as vxworks, psos, vrtx, etc... And we
wrongly assumed that for these RTOSes the switch hook was not called
when switching to the idle task. So, your patch is indeed neeeded. We
also probably need to change code in some places to avoid missing the
switches which take place when changing mode.

-- 
					    Gilles.

Re: [Xenomai-help] Monitoring Xenomai scheduler switches

[Philippe Gerum]

On Thu, 2010-05-20 at 16:26 +0200, Tschaeche IT-Services wrote:
> Hi,
> 
> we started an application which monitors task switches
> using Xenomai 2.5.3.
> 
> For monitoring primary domain switches we hooked
> in our code by using rt_task_add_hook(T_HOOK_SWITCH)
> (storing a timestamp and the Xenomai task ID in an array,
> which is read later by user space appl from shared memory).
> 
> It seems, that our code is not called when Xenomai switches to the ROOT task.
> 
> We already had this issue with Xenomai 2.4.10
> and solved it by applying the attached patch.
> 
> How can we catch these Xenomai scheduler events in 2.5.3?
> 
> What is the reason for filtering them out?

No valid one. Patch queued in my tree, thanks.

> 
> Best regards,
> 
> 	Olli
> _______________________________________________
> Xenomai-help mailing list
> Xenomai-help@domain.hid
> https://mail.gna.org/listinfo/xenomai-help


-- 
Philippe.

Re: [Xenomai-help] Monitoring Xenomai scheduler switches

[Tschaeche IT-Services]

On Fri, May 21, 2010 at 11:28:41AM +0200, Philippe Gerum wrote:
> > ...
> > It seems, that our code is not called when Xenomai switches to the ROOT task.
> > 
> > We already had this issue with Xenomai 2.4.10
> > and solved it by applying the attached patch.
> > 
> > How can we catch these Xenomai scheduler events in 2.5.3?
> > 
> > What is the reason for filtering them out?
> 
> No valid one. Patch queued in my tree, thanks.
 
Just tested your queued patch for 2.5.3 in our build.
Looks great now: we are able to trace all context switches now :-)

Thanks,

   Olli

-- 
Tschaeche IT-Services       Tel.:  +49/9134/9089850
Dr.-Ing. Oliver Tschäche    Mobil: +49/176/20435601
Welluckenweg 4              Email: services@domain.hid
91077 Neunkirchen