linux-kernel - Re: ksoftirqd/n permanently eating 60% of a CPU

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Message-ID: <20100912185715.GA8775@rhlx01.hs-esslingen.de>
Date:	Sun, 12 Sep 2010 20:57:15 +0200
From:	Andreas Mohr <andi@...as.de>
To:	Louis-David Mitterrand <vindex+lists-linux-kernel@...rtia.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: ksoftirqd/n permanently eating 60% of a CPU

> Examining /proc/interrupts shows that "Local timer interrupts" are
> mainly firing.

> Strangely enough, the interrupt storm starts only 5 minutes or so after
> bootup.

So you're saying that the exact change in behaviour after 5 minutes
is a much increased local interrupt activity?

Something that might help in nailing down the source of the CPU load
is doing an oprofile trace (for contexts that aren't in interrupt-off periods, that is).

If it's in fact a local interrupt issue, then people such as Gleixner
or Stultz (timers) or Molnar (APIC) might know further details, IIRC.

And have you tried running powertop or manually (perhaps via sophisticated shell
script) keeping a watch on /proc/timer[list|stats]?

Andreas Mohr
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