Re: [Xenomai-help] High latencies on Core2Duo

[Philippe Gerum <philippe.gerum@domain.hid>]

Sebastian Smolorz wrote:
> Philippe Gerum wrote:
>> Sebastian Smolorz wrote:
>>> Philippe Gerum wrote:
>>>> Could you run another trace with that patch applied? TIA,
>>>
>>> Here it comes.
>>>
>>
>> Thanks. Is the latency spot regularly happening at the same place
>> after a few runs,
>> or rather randomly?
> 
> 
> I can for sure activate it with a kernel compilation with make -j2.
> Without load, it is more or less random and more seldom.
> 

Could you try booting with idle=poll just to make sure that we don't get trapped
into long wakeup latency from some idling instruction? We explicitly avoid mwait
unless forced to use it by a bootparam, but maybe something goes wrong with the
default idle code as well.

FYI, I have latency spots of the same magnitude on a Dell precision m65 laptop
here too, but I also have latency figures  < 5 us under extreme load on a
four-way Opteron-based workstation (Fujitsu Siemens) with the very same
pipeline+Xenomai combo, so there is a significant risk that a hw issue (possibly
chipset) bites us here.

TIA,

-- 
Philippe.