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Date: Fri, 05 Jun 2009 13:10:24 +0200
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-help] IRQ-Latency when in idle State on ARM
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To: Karl Tyss <tyss.k@domain.hid>
Cc: xenomai@xenomai.org

Karl Tyss wrote:
> Hi,
> 
> thank you for the quick answer.
> 
> The idea with deactivating the caches is to see if they are influencing
> this behavior. I also tried out the FCSE option and it did not help. My
> issue is that if there is a user space application that starts lots of
> short processes/threads and sleeps for a short time, in this case I get
> a large jitter. Till this point I was able to find out that it makes a
> difference if the idle task is running. 

How large ? If it is something around 200us it is normal for an ARM.
Note that the cache flush is not alone, there is also a TLB flush. If
you do not want the TLB flush, then you will have to run ucLinux.

-- 
					    Gilles.