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From: Marcelo Tosatti <mtosatti@redhat.com>
To: "Marcin Gibuła" <m.gibula@beyond.pl>
Cc: Alexander Graf <agraf@suse.de>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH] kvmclock: Ensure time in migration never goes backward
Date: Mon, 5 May 2014 20:27:10 -0300	[thread overview]
Message-ID: <20140505232710.GB20638@amt.cnet> (raw)
In-Reply-To: <5367D7BC.2040705@beyond.pl>

On Mon, May 05, 2014 at 08:26:04PM +0200, Marcin Gibuła wrote:
> >>is it possible to have kvmclock jumping forward?
> >>
> >>Because I've reproducible case when at about 1 per 20 vm restores, VM freezes for couple of hours and then resumes with date few hundreds years ahead. Happens only with kvmclock.
> >>
> >>And this patch seems to fix very similar issue so maybe it's all the same bug.
> >
> >I'm fairly sure it is the exact same bug. Jumping backward is like jumping forward by a biiiiig amount :)
> 
> Hi,
> 
> I've tested your path on my test VM... don't know if it's pure luck
> or not, but it didn't hang with over 70 restores.
> 
> The message "KVM Clock migrated backwards, using later time" fires
> every time, but VM is healthy after resume.

What is the host clocksource? (cat
/sys/devices/system/clocksource/clocksource0/current_clocksource). 

And kernel version?

  reply	other threads:[~2014-05-05 23:27 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-05 13:51 [Qemu-devel] [PATCH] kvmclock: Ensure time in migration never goes backward Alexander Graf
2014-05-05 17:46 ` Marcin Gibuła
2014-05-05 18:05   ` Alexander Graf
2014-05-05 18:26     ` Marcin Gibuła
2014-05-05 23:27       ` Marcelo Tosatti [this message]
2014-05-05 23:31         ` Marcelo Tosatti
2014-05-06  8:07           ` Marcin Gibuła
2014-05-06  7:11         ` Alexander Graf
2014-05-06  7:37         ` Marcin Gibuła
2014-05-05 23:23 ` Marcelo Tosatti
2014-05-05 23:31   ` Marcelo Tosatti
2014-05-06  7:18     ` Alexander Graf
2014-05-06 19:54       ` Marcin Gibuła
2014-05-07 23:23         ` Marcelo Tosatti
2014-05-07 23:21       ` Marcelo Tosatti
2014-05-07 23:29         ` Alexander Graf
2014-05-06  7:16   ` Alexander Graf
2014-05-07 10:04     ` Nick Thomas
2014-05-08  1:33 ` Marcelo Tosatti
2014-05-08  7:21   ` Alexander Graf
2014-05-09  2:28     ` Marcelo Tosatti
2014-05-09 11:53       ` Paolo Bonzini
2014-05-12 20:26         ` Alexander Graf
2014-05-14  7:26           ` Marcelo Tosatti
2014-05-14  6:47         ` Marcelo Tosatti

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