Re: RT Throtteling with PREEMT-RT on UBIFS root fs update

From: Tim Sander
Date: Thu Nov 17 2011 - 08:55:45 EST


Hi

This is just a followup
> We are having a problem with a slightly patched (some platform patches,
> newest stable ubifs patches) 3.0.7-rt20 kernel after updating the firmware
> on the first boot we get a message:
> sched: RT throttling activated
> and ksoftirqd/0 taking 95% of the cpu time.
RT throtteling is still activate with 3.0.9-rt25 (+ ubifs stable patches) but
now ksoftirqd/0 is not going berserk.
> Interestingly this only happens after the ubifs root has been updated on
> the first boot (and not allways). Subsequent boot problems have not been
> seen.
Ok the only nitpik that is left, that the processor activates rt throtteling
after the first boot with updated ubifs image.
> Any ideas whats causing this?
Well it can be said that it is not ksoftirqd/0 going berserk which is
triggering this. So i guess when this message is printed it just shows that
the cpu had been temporarily overloded with work in interrupt context.
Is there more harm to expect from this message or save to ignore if the
systemload is normal again?

Best regards
Tim

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