WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] Re: [PATCH] [Bugfix][pv-ops] Guest get stucked after migrati

To: xen-devel@xxxxxxxxxxxxxxxxxxx, Jeremy Fitzhardinge <Jeremy.Fitzhardinge@xxxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH] [Bugfix][pv-ops] Guest get stucked after migration
From: Frank Pan <frankpzh@xxxxxxxxx>
Date: Tue, 22 Mar 2011 12:19:53 +0800
Cc:
Delivery-date: Mon, 21 Mar 2011 21:21:05 -0700
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type:content-transfer-encoding; bh=YEZCA4BQJBmY+ZCANUUAsgusjWh7i9JF/Fv5nd7f7lQ=; b=XR0mGSwul05bf4XXOYeVELxbzbneItkGOT8RL/ejugePWV/tE6gcIZCMS9LBr9fZSw oSLUmoh+cSWnbVeXe6eJf/jk2oDqHtYxR/dNDK1RbrCDRq7QkbQxeyJLdP5xoGf0mv9b L+UhT2Ai6CdDTZuKlNoRVfy3dyOZyYZvhsHYA=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type:content-transfer-encoding; b=hPz0INFqdICSp/PMUMCGYVwSwlAQLOdETDnVeF/ZElEjf+3b4STvbrezFtrUDFTWpT VmtN9rjOAhzFf/wAiKXXqKS+4U03xBFhFO2edHxJEVFJs0UHrFlHKoGKm4Zovz0+nR4P W0RYVNrfXH4rt/0qd2HhX3d2CWUMrHZV2PeYc=
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <AANLkTin6ktRWAjYWKWhxA9AcscKhCdVJWqgfHaDP0B7q@xxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <AANLkTin6ktRWAjYWKWhxA9AcscKhCdVJWqgfHaDP0B7q@xxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
On Tue, Mar 22, 2011 at 2:26 AM, Frank Pan <frankpzh@xxxxxxxxx> wrote:
> In recent pv-ops kernel, pvclock is not guaranteed as monotone.
> After a migration, pvclock can produce smaller cycle count.
>
> [The test is performed on next-2.6.32 tree]
> The issue occured when uptime(sender) > uptime(target), and with
> CONFIG_GENERIC_TIME. The guest get stucked after the migration,
> doing a huge loop inside update_wall_time, until the overflow of
> 64-bit unsigned offset.
>
> The following patch fixed this issue by introducing a global sign.
> Xen pvclock will update the cycle_last with the newest cycle count
> on the first read after migration.

It seems the issue is not that simple. This issue can be well solved by
the suspend/resume code of timekeeper sysdev. However, the recent
code may think this is not necessary on hvm domain. (How can I find the
reason here?)

I don't know if it's ok to add a pair of sysdev_suspend/sysdev_resume inside
xen_hvm_suspend. If not, this patch can be a quickfix/solution.

Any ideas on this issue?

-- 
潘震皓, Frank Pan

Computer Science and Technology
Tsinghua University

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel