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Groups > linux.kernel > #1628293 > unrolled thread

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

Started byFrederic Weisbecker <fweisbec@gmail.com>
First post2017-04-21 16:10 +0200
Last post2017-04-24 19:10 +0200
Articles 3 — 2 participants

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  [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

#1628293 — [PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2

FromFrederic Weisbecker <fweisbec@gmail.com>
Date2017-04-21 16:10 +0200
Subject[PATCH 0/2] nohz: Deal with clock reprogram skipping issues v2
Message-ID<tyHq2-6LU-35@gated-at.bofh.it>
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(-)

-- 
2.7.4

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#1629598

FromFrederic Weisbecker <fweisbec@gmail.com>
Date2017-04-24 16:10 +0200
Message-ID<tzMQF-80I-1@gated-at.bofh.it>
In reply to#1628293
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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#1629796 — [tip:timers/urgent] nohz: Print more debug info in tick_nohz_stop_sched_tick()

Fromtip-bot for Frederic Weisbecker <tipbot@zytor.com>
Date2017-04-24 19:10 +0200
Subject[tip:timers/urgent] nohz: Print more debug info in tick_nohz_stop_sched_tick()
Message-ID<tzPES-1jt-19@gated-at.bofh.it>
In reply to#1629598
Commit-ID:  098991fccfc7c0dd5fdfc6ed2ed965ad80f14be5
Gitweb:     http://git.kernel.org/tip/098991fccfc7c0dd5fdfc6ed2ed965ad80f14be5
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Mon, 24 Apr 2017 16:04:37 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 24 Apr 2017 16:27:09 +0200

nohz: Print more debug info in tick_nohz_stop_sched_tick()

Print more debug info when triggering this warning:

  > ------------[ cut here ]------------
  > WARNING: CPU: 0 PID: 0 at kernel/time/tick-sched.c:874 __tick_nohz_idle_enter+0x461/0x490

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: James Hartsock <hartsjc@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Wright <tim@binbash.co.uk>
Link: http://lkml.kernel.org/r/20170424140436.GD21353@lerouge
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/time/tick-sched.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index be7ca4d..b2df684 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -789,6 +789,7 @@ 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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