On Thu, 28 April 2011 Thomas Gleixner wrote: > On Thu, 28 Apr 2011, Sedat Dilek wrote: > > On Thu, Apr 28, 2011 at 3:30 PM, Mike Galbraith wrote: > > rt_rq[0]: > > .rt_nr_running : 0 > > .rt_throttled : 0 > > > .rt_time : 888.893877 > > > .rt_time : 950.005460 > > So rt_time is constantly accumulated, but never decreased. The > decrease happens in the timer callback. Looks like the timer is not > running for whatever reason. > > Can you add the following patch as well ? > > Thanks, > > tglx > > --- linux-2.6.orig/kernel/sched.c > +++ linux-2.6/kernel/sched.c > @@ -172,7 +172,7 @@ static enum hrtimer_restart sched_rt_per > idle = do_sched_rt_period_timer(rt_b, overrun); > } > > - return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; > + return HRTIMER_RESTART; This doesn't help here. Be it applied on top of the others, full diff attached or applied alone (with throttling printk). Could it be that NO_HZ=y has some importance in this matter? Extended throttling printk (Linus asked what exact values were looking like): [ 401.000119] sched: RT throttling activated 950012539 > 950000000 Equivalent to what Sedat sees (/proc/sched_debug): rt_rq[0]: .rt_nr_running : 2 .rt_throttled : 1 .rt_time : 950.012539 .rt_runtime : 950.000000 /proc/$(pidof rcu_kthread)/sched captured at regular intervals: Thu Apr 28 21:33:41 CEST 2011 rcu_kthread (6, #threads: 1) --------------------------------------------------------- se.exec_start : 0.000000 se.vruntime : 0.000703 se.sum_exec_runtime : 903.067982 nr_switches : 23752 nr_voluntary_switches : 23751 nr_involuntary_switches : 1 se.load.weight : 1024 policy : 1 prio : 98 clock-delta : 912 Thu Apr 28 21:34:11 CEST 2011 rcu_kthread (6, #threads: 1) --------------------------------------------------------- se.exec_start : 0.000000 se.vruntime : 0.000703 se.sum_exec_runtime : 974.899495 nr_switches : 25721 nr_voluntary_switches : 25720 nr_involuntary_switches : 1 se.load.weight : 1024 policy : 1 prio : 98 clock-delta : 1098 Thu Apr 28 21:34:41 CEST 2011 rcu_kthread (6, #threads: 1) --------------------------------------------------------- se.exec_start : 0.000000 se.vruntime : 0.000703 se.sum_exec_runtime : 974.899495 nr_switches : 25721 nr_voluntary_switches : 25720 nr_involuntary_switches : 1 se.load.weight : 1024 policy : 1 prio : 98 clock-delta : 1126 Thu Apr 28 21:35:11 CEST 2011 rcu_kthread (6, #threads: 1) > } > > static