Re: [tip:core/rcu] Revert "rcu: Decrease memory-barrier usagebased on semi-formal proof"

[Paul E. McKenney]

On Thu, May 26, 2011 at 07:25:53AM -0700, Paul E. McKenney wrote:
> On Thu, May 26, 2011 at 08:13:48AM +0200, Ingo Molnar wrote:
> > 
> > * Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> 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@xxxxxxxxx>
> > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> > 
> > 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.

By the way, how would you like to proceed with the fixes thus far?
I have put them on -rcu for -next testing, FWIW.

							Thanx, Paul
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