Re: [Xenomai] Alchemy periodic task and timer overruns

[Philippe Gerum <rpm@xenomai.org>]

On 11/30/2015 01:09 PM, Gilles Chanteperdrix wrote:
> On Mon, Nov 30, 2015 at 11:57:49AM +0100, Registrierungen wrote:
>> Hello,
>>
>> i've got a problem using the periodic tasks.
>> I am using the alchemy tasks running 10kHz and i get a lot of  (up ~ 
>> 10)  timer overruns / sek calling rt_task_wait_period. (each overrung 
>> has an amount of 1 ).
>>
>> I extracted the task to a test program. In this example he is doing 
>> nothing between the rt_task_wait_period calls.
>> Ironically i get more (up ~ 100) timer overruns / sek calling 
>> rt_task_wait_period.
>>
>> I am running a AMD-G Series, x86_64 with SMP.
>> I tested on xenomai 3rc2 and xenomai 3.0.1 (with optimized kernel, 
>> following the documentation) with same results.
>>
>> Any idea, what is going wrong?
>> How can i find out where is the problem?
> 
> Do you observe the same problem with xenomai "latency" test? If yes,
> then using the I-pipe tracer should help you. Note that all that is
> documented in the "troubleshooting" guide:
> 
> http://xenomai.org/troubleshooting-a-dual-kernel-configuration/#the_latency_test_shows_high_latencies
> 

Also, demo/altency implements the very same latency test using the
alchemy API, with rt_task_wait_period() and friends. You may want to
check whether such test works fine on your platform.

-- 
Philippe.