lots of brief rcu stalls.

Dave Jones
2013-12-04T23:28:48Z

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?

Dave