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Date: Thu, 26 May 2011 07:25:53 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Yinghai Lu <yinghai@kernel.org>, linux-kernel@vger.kernel.org,
        mingo@redhat.com, hpa@zytor.com, tglx@linutronix.de
Subject: Re: [tip:core/rcu] Revert "rcu: Decrease memory-barrier usage
 based on semi-formal proof"
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On Thu, May 26, 2011 at 08:13:48AM +0200, Ingo Molnar wrote:
> 
> * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
> 
> > rcu: Start RCU kthreads in TASK_INTERRUPTIBLE state
> > 
> > Upon creation, kthreads are in TASK_UNINTERRUPTIBLE state, which can
> > result in softlockup warnings.  Because some of RCU's kthreads can
> > legitimately be idle indefinitely, start them in TASK_INTERRUPTIBLE
> > state in order to avoid those warnings.
> > 
> > Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> 
> this should also solve load average artifacts - do not 
> TASK_UNINTERRUPTIBLE tasks skew the load upwards?

Quite possibly -- in this case the artifacts would appear just after
boot, and would disappear as soon as the RCU kthreads had something
to do.

							Thanx, Paul