Re: i.MX28 milliseconds latencies, interrupts disabled in arch_cpu_idle?

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

Le 21/04/2014 11:11, Stanislav Meduna a écrit :
> On 19.04.2014 12:36, Gilles Chanteperdrix wrote:
> 
>> #1 can be avoided by using the ARM FCSE extension.
> 
> An interesting stuff, thanks for pointing this up.
> 
>> A patch exists for #1 which is currently integrated into the Adeos patch
>> but could exist independently. I could post the patch here for Linux
>> vanilla here if there is enough interest, and let you do the merge with
>> the preempt_rt patch.
> 
> I am surely not skilled enough to merge and test this, but publishing
> the patch rebased to current kernels somewhere would be surely
> interesting.

The patch has been posted three times on the linux-arm-kernel mailing
list, and received absolutely no comments. So, it does not interest the
mainline ARM linux community. Besides armv5 cores are almost dead now.
However, it may interest the preempt_rt community, which is why I
propose to post it here. The gain in worst case latency is in the 70us
range. Merging with the preempt_rt patch should not be very difficult as
normally, there is no reason for conflicts, the patch only touches ARM
memory management, which the preempt_rt patch probably does not touch.

-- 
Gilles.
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