From: Glauber Costa <glommer@redhat.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: "Xen-devel@lists.xensource.com" <Xen-devel@lists.xensource.com>,
kvm-devel <kvm@vger.kernel.org>,
Eelco Dolstra <e.dolstra@tudelft.nl>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Virtualization <virtualization@lists.linux-foundation.org>,
Olivier Hanesse <olivier.hanesse@gmail.com>,
Avi Kivity <avi@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] x86/pvclock-xen: zero last_value on resume
Date: Tue, 26 Oct 2010 15:48:54 -0200 [thread overview]
Message-ID: <1288115334.3530.7.camel@mothafucka.localdomain> (raw)
In-Reply-To: <4CC708DE.1070000@goop.org>
On Tue, 2010-10-26 at 09:59 -0700, Jeremy Fitzhardinge wrote:
>
> If the guest domain has been suspend/resumed or migrated, then the
> system clock backing the pvclock clocksource may revert to a smaller
> value (ie, can be non-monotonic across the migration/save-restore).
> Make sure we zero last_value in that case so that the domain
> continues to see clock updates.
>
> [ I don't know if kvm needs an analogous fix or not. ]
After migration, save/restore, etc, we issue an ioctl where we tell
the host the last clock value. That (in theory) guarantees monotonicity.
I am not opposed to this patch in any way, however.
next prev parent reply other threads:[~2010-10-26 17:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-26 16:59 [PATCH] x86/pvclock-xen: zero last_value on resume Jeremy Fitzhardinge
2010-10-26 17:48 ` Glauber Costa [this message]
2010-10-27 18:53 ` [Xen-devel] " Jeremy Fitzhardinge
2010-10-27 20:59 ` H. Peter Anvin
2010-11-03 12:46 ` Ian Campbell
2010-11-22 20:16 ` Jeremy Fitzhardinge
2010-11-26 10:40 ` Ingo Molnar
2010-11-26 22:29 ` Jeremy Fitzhardinge
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