From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: S3 sleep in dom0 breaks dom0<->domU wallclock synchronization Date: Mon, 5 Jul 2010 20:26:42 +0100 Message-ID: References: <4C322FF9.1050601@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C322FF9.1050601@goop.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jeremy Fitzhardinge Cc: "xen-devel@lists.xensource.com" , Jeremy Fitzhardinge , Joanna Rutkowska , Rafal Wojtczuk List-Id: xen-devel@lists.xenproject.org On 05/07/2010 20:18, "Jeremy Fitzhardinge" wrote: > So the problem is that dom0 does the S3 suspend/resume, and presumably > its wallclock time is updated properly via Linux's normal mechanisms. > But the S3 suspend/resume is unnoticed by all the domUs, so they don't > know that an enormous amount of time has passed in an instant? Does > that affect all the guest clocks, or just wallclock? Um, just wallclock I think? > How does Xen deal with the S3 suspend/resume? Does the system clock > just keep ticking as usual (so the whole suspended time appears to be > sub-nanosecond), but the wallclock offset gets updated? This. -- Keir > Or does it try > to workout how long the suspended time was and adjusts the system time > accordingly? That would allow guest timekeeping to compensate for the > suspended time, assuming they can deal with large forward leaps.