Re: lots of brief rcu stalls.
From: Paul E. McKenney
Date: Wed Dec 04 2013 - 21:44:27 EST
On Wed, Dec 04, 2013 at 08:22:06PM -0500, Dave Jones wrote:
> On Wed, Dec 04, 2013 at 04:16:14PM -0800, Paul E. McKenney wrote:
> > On Wed, Dec 04, 2013 at 06:28:38PM -0500, Dave Jones wrote:
> > > Paul,
> > > I'm seeing this happening more and more lately...
> > >
> > > [ 771.786462] INFO: rcu_preempt detected stalls on CPUs/tasks:
> > > [ 771.786552] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 771.786574] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 771.786595] (detected by 0, t=6502 jiffies, g=20611, c=20610, q=0)
> > > [ 771.786620] INFO: Stall ended before state dump start
> > > [ 966.724546] INFO: rcu_preempt detected stalls on CPUs/tasks:
> > > [ 966.724854] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 966.724931] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 966.725005] (detected by 0, t=26007 jiffies, g=20611, c=20610, q=0)
> > > [ 966.725093] INFO: Stall ended before state dump start
> > > [ 1161.661459] INFO: rcu_preempt detected stalls on CPUs/tasks:
> > > [ 1161.661763] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 1161.661840] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 1161.661915] (detected by 0, t=45512 jiffies, g=20611, c=20610, q=0)
> > > [ 1161.662001] INFO: Stall ended before state dump start
> > > [ 1356.598205] INFO: rcu_preempt detected stalls on CPUs/tasks:
> > > [ 1356.598513] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 1356.598590] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 1356.598664] (detected by 0, t=65017 jiffies, g=20611, c=20610, q=0)
> > > [ 1356.598751] INFO: Stall ended before state dump start
> > > [ 1551.536099] INFO: rcu_preempt detected stalls on CPUs/tasks:
> > > [ 1551.536408] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 1551.536485] Tasks blocked on level-0 rcu_node (CPUs 0-3):
> > > [ 1551.536559] (detected by 0, t=84522 jiffies, g=20611, c=20610, q=0)
> > > [ 1551.536645] INFO: Stall ended before state dump start
> > >
> > > While it's apparently a non-problem, it's pretty noisy.
> > > Any ideas?
> >
> > Does the following help?
>
> Seems so so far!
Keeping fingers firmly crossed...
Thanx, Paul
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