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Subject: Re: find_busiest_group using lots of CPU
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>, mingo@elte.hu,
       Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
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Date: Tue, 06 Oct 2009 14:04:21 +0200
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On Tue, 2009-10-06 at 13:20 +0200, Jens Axboe wrote:
> > > io_schedule() straight into find_busiest_group() leads me to think this
> > > could be SD_BALANCE_NEWIDLE, does something like:
> > > 
> > > for i in /proc/sys/kernel/sched_domain/cpu*/domain*/flags; 
> > > do 
> > >     val=`cat $i`; echo $((val & ~0x02)) > $i; 
> > > done
> > > 
> > > [ assuming SCHED_DEBUG=y ]
> > > 
> > > Cure things?
> > 
> > I can try,
> 
> It does, it's gone from the profiles.

Hrmm,. ok. I'll go prod at the NEWIDLE bits to see if anything stands
out.

If only perf-annotate could generate annotated C... maybe I'll look at
that.

Thanks!