From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Guest kernel hangs in smp kvm for older kernelsprior to tsc sync cleanup Date: Wed, 19 Dec 2007 19:09:48 +0200 Message-ID: <4769505C.5020309@qumranet.com> References: <47680173.6060606@qumranet.com> <47692A47.4040803@argo.co.il><5d6222a80712190732h515a63e6y49c64c0f572f044@mail.gmail.com> <200712192225.53748.amit.shah@qumranet.com> <47694F35.6070401@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-kernel , Avi Kivity , Gerd Hoffmann To: dor.laor-atKUWr5tajBWk0Htik3J/w@public.gmane.org Return-path: In-Reply-To: <47694F35.6070401-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Dor Laor wrote: >> > > >> > > vmx (and svm) allow us to add an offset to the physical tsc. We >> set it >> > > on startup to -tsc (so that an rdtsc on boot would return 0), and >> > > massage it on vcpu migration so that guest rdtsc is monotonic. >> > > >> > > The net effect is that tsc on a vcpu can experience large forward >> jumps >> > > and changes in rate, but no negative jumps. >> > >> > Changes in rate does not sound good. It's possibly what's screwing up >> > my paravirt clock implementation in smp. >> >> Do you mean in the case of VM migration, or just starting them on a >> single >> host? >> > It's the cpu preemption stuff on local host and not VM migration No, migrating a vcpu to another cpu. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- SF.Net email is sponsored by: Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace