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Re: [PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2

From Frederic Weisbecker <fweisbec@gmail.com>
Newsgroups linux.kernel
Subject Re: [PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2
Date 2017-04-24 16:10 +0200
Message-ID <tzMQF-80I-1@gated-at.bofh.it> (permalink)
References <tyHq2-6LU-35@gated-at.bofh.it> <tzHej-4xn-29@gated-at.bofh.it>
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On Mon, Apr 24, 2017 at 10:08:35AM +0200, Ingo Molnar wrote:
> 
> * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> 
> > As suggested by Thomas Gleixner, the second patch now integrates
> > a fix in case the sanity check fails and the clockevent isn't programmed
> > as expected.
> > 
> > Frederic Weisbecker (2):
> >   nohz: Fix again collision between tick and other hrtimers
> >   tick: Make sure tick timer is active when bypassing reprogramming
> > 
> >  kernel/time/tick-sched.c | 33 ++++++++++++++++++++++++++++++---
> >  kernel/time/tick-sched.h |  2 ++
> >  2 files changed, 32 insertions(+), 3 deletions(-)
> 
> So I think one of these is causing a new warning on latest -tip:
> 
> [  333.341756] ------------[ cut here ]------------
> [  333.346404] WARNING: CPU: 0 PID: 0 at kernel/time/tick-sched.c:874 __tick_nohz_idle_enter+0x461/0x490

Oh I'll never be done with that bug :)

Ok I just booted your config with tip/master and didn't see the warning.
But the boot seem to be stalled some time after mounting the root fs.

Can you please try the following patch and tell me what it returns to you?

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index c47d135..6d72e8b 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -872,6 +872,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
 			goto out;
 
 		WARN_ON_ONCE(1);
+		printk_once("basemono: %llu ts->next_tick: %llu dev->next_event: %llu\n", basemono, ts->next_tick, dev->next_event);
 	}
 
 	/*

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Thread

[PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2 Frederic Weisbecker <fweisbec@gmail.com> - 2017-04-21 16:10 +0200
  Re: [PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2 Frederic Weisbecker <fweisbec@gmail.com> - 2017-04-24 16:10 +0200
    [tip:timers/urgent] nohz: Print more debug info in  tick_nohz_stop_sched_tick() tip-bot for Frederic Weisbecker <tipbot@zytor.com> - 2017-04-24 19:10 +0200
    Re: [PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2 Frederic Weisbecker <fweisbec@gmail.com> - 2017-04-26 17:00 +0200
      Re: [PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2 Ingo Molnar <mingo@kernel.org> - 2017-04-26 20:50 +0200
        Re: [PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2 Frederic Weisbecker <fweisbec@gmail.com> - 2017-04-26 23:10 +0200

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