Re: lots of brief rcu stalls.

2013-12-05 Thread Paul E. McKenney
On Thu, Dec 05, 2013 at 12:15:50PM -0500, Dave Jones wrote: > On Thu, Dec 05, 2013 at 08:49:12AM -0800, Paul E. McKenney wrote: > > > But what workload are you running that causes this? The only way I > > can think of to make this happen requires that you have at least one > > CPU spending mor

Re: lots of brief rcu stalls.

2013-12-05 Thread Dave Jones
On Thu, Dec 05, 2013 at 08:49:12AM -0800, Paul E. McKenney wrote: > But what workload are you running that causes this? The only way I > can think of to make this happen requires that you have at least one > CPU spending more than 21 seconds running continuously in kernel mode. > Is that wha

Re: lots of brief rcu stalls.

2013-12-05 Thread Paul E. McKenney
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:

Re: lots of brief rcu stalls.

2013-12-04 Thread Paul E. McKenney
On Wed, Dec 04, 2013 at 06:36:05PM -0800, Joe Perches wrote: > On Wed, 2013-12-04 at 18:18 -0800, Eric Dumazet wrote: > > On Wed, 2013-12-04 at 16:16 -0800, Paul E. McKenney wrote: > > > + ULONG_CMP_GE(ACCESS_ONCE(jiffies), rdp->rsp->jiffies_resched)) { > > perhaps time_before_eq > > > jiffie

Re: lots of brief rcu stalls.

2013-12-04 Thread Paul E. McKenney
On Wed, Dec 04, 2013 at 06:18:30PM -0800, Eric Dumazet wrote: > On Wed, 2013-12-04 at 16:16 -0800, Paul E. McKenney wrote: > > + if (rdp->rsp == rcu_state && > > + ULONG_CMP_GE(ACCESS_ONCE(jiffies), rdp->rsp->jiffies_resched)) { > > + rdp->rsp->jiffies_resched += 5; > > +

Re: lots of brief rcu stalls.

2013-12-04 Thread Paul E. McKenney
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:

Re: lots of brief rcu stalls.

2013-12-04 Thread Joe Perches
On Wed, 2013-12-04 at 18:18 -0800, Eric Dumazet wrote: > On Wed, 2013-12-04 at 16:16 -0800, Paul E. McKenney wrote: > > + ULONG_CMP_GE(ACCESS_ONCE(jiffies), rdp->rsp->jiffies_resched)) { perhaps time_before_eq > jiffies should not need ACCESS_ONCE(), right ? > > It is one of the few variab

Re: lots of brief rcu stalls.

2013-12-04 Thread Eric Dumazet
On Wed, 2013-12-04 at 16:16 -0800, Paul E. McKenney wrote: > + if (rdp->rsp == rcu_state && > + ULONG_CMP_GE(ACCESS_ONCE(jiffies), rdp->rsp->jiffies_resched)) { > + rdp->rsp->jiffies_resched += 5; > + resched_cpu(rdp->cpu); > + } > + > return 0; > } j

Re: lots of brief rcu stalls.

2013-12-04 Thread 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

Re: lots of brief rcu stalls.

2013-12-04 Thread Paul E. McKenney
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

lots of brief rcu stalls.

2013-12-04 Thread Dave Jones
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=2061