Re: NOHZ: local_softirq_pending

[Iratxo Pichel Ortiz <ipichel@albentia.com>]

Thomas Gleixner wrote:
> Please bzip2 it and upload it somewhere as it's probably too large for
> the mailinglist.
>   
Please find 3 realizations at:
http://www.proyectoradio.com/webdocs/rtkernel/trace.bz2
http://www.proyectoradio.com/webdocs/rtkernel/trace2.bz2
http://www.proyectoradio.com/webdocs/rtkernel/trace3.bz2

Just in case they get lost sometime in the future, at the end of this 
email is the result of "tail -30 trace3", hopefully it is enough of that 
file.

Having read the three of them, regardless of the last process before the 
"NOHZ...", there is always a call to the FPE emulator. I am going to do 
some tests changing the FPE emulator, in case it helps.

Thanks a lot,

    Iratxo.
> Thanks,
>
> 	tglx
> -------------->
> Subject: debug-nohz-issue.patch
> From: Thomas Gleixner <tglx@linutronix.de>
> Date: Thu, 18 Jun 2009 01:41:01 +0200
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  kernel/time/tick-sched.c |    2 ++
>  1 file changed, 2 insertions(+)
>
> Index: linux-2.6-tip/kernel/time/tick-sched.c
> ===================================================================
> --- linux-2.6-tip.orig/kernel/time/tick-sched.c
> +++ linux-2.6-tip/kernel/time/tick-sched.c
> @@ -250,6 +250,8 @@ void tick_nohz_stop_sched_tick(int inidl
>  	if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
>  		static int ratelimit;
>  
> +		tracing_off();
> +
>  		if (ratelimit < 10) {
>  			printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
>  			       local_softirq_pending());
>
>   

              sh-1162  [000] 4154504576.502616: n_tty_set_room <-n_tty_read
              sh-1162  [000] 4154504576.502616: schedule_timeout 
<-n_tty_read
              sh-1162  [000] 4154504576.502616: schedule <-schedule_timeout
              sh-1162  [000] 4154504576.502616: __schedule <-schedule
              sh-1162  [000] 4154504576.502616: rcu_qsctr_inc <-__schedule
              sh-1162  [000] 4154504576.502616: deactivate_task <-__schedule
              sh-1162  [000] 4154504576.502616: dequeue_task 
<-deactivate_task
              sh-1162  [000] 4154504576.502616: update_avg <-dequeue_task
              sh-1162  [000] 4154504576.502616: dequeue_task_fair 
<-dequeue_task
              sh-1162  [000] 4154504576.502616: update_curr 
<-dequeue_task_fair
              sh-1162  [000] 4154504576.502616: clear_buddies 
<-dequeue_task_fair
              sh-1162  [000] 4154504576.502616: __clear_buddies 
<-clear_buddies
              sh-1162  [000] 4154504576.502616: update_min_vruntime 
<-dequeue_task_fair
              sh-1162  [000] 4154504576.502616: put_prev_task_fair 
<-__schedule
              sh-1162  [000] 4154504576.502616: check_spread 
<-put_prev_task_fair
              sh-1162  [000] 4154504576.502616: pick_next_task_rt 
<-__schedule
              sh-1162  [000] 4154504576.502616: pick_next_task_fair 
<-__schedule
              sh-1162  [000] 4154504576.502616: pick_next_task_idle 
<-__schedule
              sh-1162  [000] 4154504576.502616: calc_load_account_active 
<-pick_next_task_idle
              sh-1162  [000] 4154504576.502616: __rcu_read_lock 
<-__atomic_notifier_call_chain
              sh-1162  [000] 4154504576.502616: nwfpe_notify 
<-notifier_call_chain
              sh-1162  [000] 4154504576.502616: dsp_do <-notifier_call_chain
              sh-1162  [000] 4154504576.502616: __rcu_read_unlock 
<-__atomic_notifier_call_chain
          <idle>-0     [000] 4154504576.502616: finish_task_switch 
<-__schedule
          <idle>-0     [000] 4154504576.502616: 
tick_nohz_stop_sched_tick <-cpu_idle
          <idle>-0     [000] 4154504576.502616: ktime_get 
<-tick_nohz_stop_sched_tick
          <idle>-0     [000] 4154504576.502616: ktime_get_ts <-ktime_get
          <idle>-0     [000] 4154504576.502616: getnstimeofday 
<-ktime_get_ts
          <idle>-0     [000] 4154504576.502616: ixp4xx_get_cycles 
<-getnstimeofday
          <idle>-0     [000] 4154504576.502616: set_normalized_timespec 
<-ktime_get_ts

-- 
Iratxo Pichel Ortiz
Software Development Manager

Albentia Systems S.A.
http://www.albentia.com

Tel: +34 914400567
Cel: +34 663808405
Fax: +34 914400569

C\Margarita Salas 22
Parque Tecnológico de Leganés
Leganés (28918)
Madrid
Spain

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