From: Peter Zijlstra <peterz@infradead.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Laurence Oberman <loberman@redhat.com>,
Vincent Whitchurch <vincent.whitchurch@axis.com>,
Michal Hocko <mhocko@suse.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] watchdog/softlockup: Report the same softlockup regularly
Date: Mon, 21 Oct 2019 14:43:39 +0200 [thread overview]
Message-ID: <20191021124339.GE1817@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190819104732.20966-3-pmladek@suse.com>
On Mon, Aug 19, 2019 at 12:47:31PM +0200, Petr Mladek wrote:
> Softlockup report means that there is no progress on the given CPU. It
> might be a "short" affair where the system gets recovered. But often
> the system stops being responsive and need to get rebooted.
>
> The softlockup might be root of the problems or just a symptom. It might
> be a deadlock, livelock, or often repeated state.
>
> Regular reports help to distinguish different situations. Fortunately,
> the watchdog is finally able to show correct information how long
> softlockup_fn() was not scheduled.
>
> Report before this patch:
>
> [ 320.248948] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4916]
>
> And after this patch:
>
> [ 480.372418] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4943]
> [ 508.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 52s! [cat:4943]
> [ 548.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 89s! [cat:4943]
> [ 576.372351] watchdog: BUG: soft lockup - CPU#2 stuck for 115s! [cat:4943]
>
> Note that the horrible code never really worked before the accounting
> was fixed. The last working timestamp was regularly lost by the many
> touch*watchdog() calls.
So what's the point of patch 1? Just confusing people?
next prev parent reply other threads:[~2019-10-21 12:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-19 10:47 [PATCH 0/3] watchdog/softlockup: Make softlockup reports more reliable and useful Petr Mladek
2019-08-19 10:47 ` [PATCH 1/3] watchdog/softlockup: Preserve original timestamp when touching watchdog externally Petr Mladek
2019-10-21 12:42 ` Peter Zijlstra
2019-10-21 13:04 ` Petr Mladek
2019-08-19 10:47 ` [PATCH 2/3] watchdog/softlockup: Report the same softlockup regularly Petr Mladek
2019-10-21 12:43 ` Peter Zijlstra [this message]
2019-10-21 13:40 ` Petr Mladek
2019-10-21 14:09 ` Peter Zijlstra
2019-08-19 10:47 ` [PATCH 3/3] Test softlockup Petr Mladek
2019-10-21 12:45 ` Peter Zijlstra
2019-10-21 13:06 ` Petr Mladek
2019-10-21 12:32 ` [PATCH 0/3] watchdog/softlockup: Make softlockup reports more reliable and useful Petr Mladek
-- strict thread matches above, loose matches on Subject: below --
2019-06-05 14:09 [RFC " Petr Mladek
2019-06-05 14:09 ` [PATCH 2/3] watchdog/softlockup: Report the same softlockup regularly Petr Mladek
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