From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: suspend evetchn creation failure Date: Tue, 11 Mar 2014 13:39:00 -0400 Message-ID: <20140311173900.GF14684@phenom.dumpdata.com> References: <1394536892.18366.43.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Shriram Rajagopalan Cc: "xen-devel@lists.xen.org" , Ian Campbell , Prateek Sharma List-Id: xen-devel@lists.xenproject.org On Tue, Mar 11, 2014 at 09:39:21AM -0700, Shriram Rajagopalan wrote: > On Tue, Mar 11, 2014 at 4:21 AM, Ian Campbell wrote: > > > On Mon, 2014-03-03 at 12:24 -0500, Prateek Sharma wrote: > > > Hi all, > > > During xm save, I xc_save throws up this error : > > > "failed to get the suspend evtchn port". > > > From my understanding, the port is supposed to be stored by > > > xenstore in /local/domain/, but I can't see the port being created using > > > xenstore-ls either. > > > > I think this event channel is created by the guest and written to > > xenstore as part of support for the fast event channel based save > > mechanism used by e.g. remus. In its absence save/suspend is triggered > > via the traditional method of the toolstack writing commands to the > > "control/shutdown" node. > > > > IIRC the fast event channel based save stuff is not in mainline kernels, > > so the tools message is correct but harmless. > > > > CCing Shriram (Remus maintainer) in case I've got all the above wrong... > > > > > Ian is right. Mainline kernels don't have suspend event channel. > Unfortunately, not having suspend event channel results in a pretty big > performance hit, > as each suspend call takes about 7-10ms and a resume takes 2-4ms. You are > looking > at approx 10% loss of execution time just to suspend/resume the VM > (assuming > a 100ms checkpoint interval). What is involved in implementing it? > > However, OpenSUSE kernels have suspend event channel support. That said I > have > had issues with 3.7+ versions (IIRC), where the kernel starts crashing > during > recovery (which is basically a full resume). > > shriram > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel