Re: [Xenomai-help] Cyclictest

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Jan Kiszka wrote:
> Gilles Chanteperdrix wrote:
> 
>>Jan Kiszka wrote:
>>
>>>Perrine Martignoni wrote:
>>>
>>>
>>>>Ok. I'll do this.
>>>>
>>>>But I don't understand why the same application compiled without any links
>>>>with Xenomai give different results if there is Xenomai in the kernel.
>>>
>>>[Looking at your numbers again] Hmm, maybe some rounding issue of ticks
>>>due to whatever side-effect of I-pipe. We would first of all need the
>>>usual set of information (.config, involved versions) and also
>>>/sys/devices/system/clocksource/clocksource0/current_clocksource.
>>
>>Maybe what Perrine is observing is simply the overhead of the I-pipe ?
>>I mean, Linux is Xenomai idle task, so it is acceptable for Linux
>>numbers to be a bit worse than when Xenomai is not running.
> 
> 
> I bit worse is expected. But I think we are seeing 1 or 2 ticks wake-up
> delays here. As far as I understood, they are not due to Xenomai
> consuming significant cycles in the background, are they, Perrine?

What I see is latencies 5us longer. 5us on ARM is almost nothing, keep
in mind that a simple syscall on ARM already takes 10 us.

-- 
                                                 Gilles Chanteperdrix