Re: lots of brief rcu stalls.

[Dave Jones]

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!

	Dave

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