[Xenomai-help] accessing context switch counter from rttask

[Xenomai-help] accessing context switch counter from rttask

[Gsellmann Peter]

Hi!

I searched for a while and found this snippet

RT_TASK *rt = rt_task_self();
int x = rt->thread_base.stat.csw;

should give the number of context switches, but:
RT_TASK in non-kernel mode is only RT_TASK_PLACEHOLDER so i have no
access to thread_base!

Is there an official way to get this info (w/o opening
"/proc/xenomai/...")?


TIA,
Peter

Re: [Xenomai-help] accessing context switch counter from rttask

[Jan Kiszka]

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Gsellmann Peter wrote:
> Hi!
> 
> I searched for a while and found this snippet
> 
> RT_TASK *rt = rt_task_self();
> int x = rt->thread_base.stat.csw;
> 
> should give the number of context switches, but:
> RT_TASK in non-kernel mode is only RT_TASK_PLACEHOLDER so i have no
> access to thread_base!
> 
> Is there an official way to get this info (w/o opening
> "/proc/xenomai/...")?
> 

Not yet. You could extend RT_TASK_INFO with this statistic (obtained via
rt_task_inquire). There is currently work in progress to add accumulated
execution times to the same interface, so this extension would fit quite
well. Patches always welcome.

Jan


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Re: [Xenomai-help] accessing context switch counter from rttask

[Jan Kiszka]

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Jan Kiszka wrote:
> Gsellmann Peter wrote:
>> Hi!
>>
>> I searched for a while and found this snippet
>>
>> RT_TASK *rt = rt_task_self();
>> int x = rt->thread_base.stat.csw;
>>
>> should give the number of context switches, but:
>> RT_TASK in non-kernel mode is only RT_TASK_PLACEHOLDER so i have no
>> access to thread_base!
>>
>> Is there an official way to get this info (w/o opening
>> "/proc/xenomai/...")?
>>
> 
> Not yet. You could extend RT_TASK_INFO with this statistic (obtained via
> rt_task_inquire). There is currently work in progress to add accumulated
> execution times to the same interface, so this extension would fit quite
> well. Patches always welcome.

Meanwhile, I added this feature to my experimental patch stack while
integrating some other new stats. See

http://www.rts.uni-hannover.de/rtaddon/patches/xenomai/

against Xenomai SVN trunk, namely

http://www.rts.uni-hannover.de/rtaddon/patches/xenomai/enhance-thread-stats.patch

Just call rt_task_inquire() and check RT_TASK_INFO::ctxswitches (there
are modeswitches and pagefaults too as we are already at it).

Feedback welcome!

Jan


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