Re: [patch 2/3] pvclock: detect watchdog reset at pvclock read

Marcelo Tosatti
2013-10-08T22:08:11Z

On Tue, Oct 08, 2013 at 09:37:05AM -0400, Don Zickus wrote:
> On Mon, Oct 07, 2013 at 10:05:17PM -0300, Marcelo Tosatti wrote:
> > Implement reset of kernel watchdogs at pvclock read time. This avoids
> > adding special code to every watchdog.
> >
> > This is possible for watchdogs which measure time based on sched_clock() or
> > ktime_get() variants.
> >
> > Suggested by Don Zickus.
> >
> > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>
> Awesome. Thanks for figuring this out Marcelo. Does that mean we can
> revert commit 5d1c0f4a now? :-)

Unfortunately no: soft lockup watchdog does not measure time based on
sched_clock but on hrtimer interrupt count :-(
(see the the softlockup code in question, perhaps you can point to
something that i'm missing).

BTW, are you OK with printing additional steal time information?
https://lkml.org/lkml/2013/6/27/755

> This meets my expectations. I'll leave it to the virt folks to figure out
> if this covers all the corner cases or not.
>
> Cheers,
> Don

Thanks