Messages in this thread | | | Date | Mon, 21 Oct 2019 16:09:26 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/3] watchdog/softlockup: Report the same softlockup regularly |
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On Mon, Oct 21, 2019 at 03:40:38PM +0200, Petr Mladek wrote: > On Mon 2019-10-21 14:43:39, Peter Zijlstra wrote: > > 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? > > I was not sure what was the expected behavior. The code actually > looked like only the first report was wanted. But it probably never > worked that way.
Not that I can remember at least :-) I normally don't bother with the actual time, and if I do then I look at the printk timestamps to figure out how long thing've been stuck.
But this is indeed nicer..
> Should I squash the two patches and send it again, please?
Probably makes sense to squash it. That also avoids having to ever expose that ugleh :-)
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