From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [kvm-devel] Guest kernel hangs in smp kvm for older kernels prior to tsc sync cleanup Date: Wed, 19 Dec 2007 17:41:17 +0200 Message-ID: <47693B9D.7080809@qumranet.com> References: <47680173.6060606@qumranet.com> <20071218221930.GA26109@elte.hu> <4768BB43.1000609@qumranet.com> <4768FE27.7020305@qumranet.com> <47690304.1090903@qumranet.com> <20071219140624.GF21282@elte.hu> <47692A47.4040803@argo.co.il> <5d6222a80712190732h515a63e6y49c64c0f572f044@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Avi Kivity , Ingo Molnar , kvm-devel , linux-kernel , Chris Wright , Gerd Hoffmann To: Glauber de Oliveira Costa Return-path: In-Reply-To: <5d6222a80712190732h515a63e6y49c64c0f572f044@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Glauber de Oliveira Costa wrote: > Changes in rate does not sound good. It's possibly what's screwing up > my paravirt clock implementation in smp. > You should renew the timebase on vcpu migration, and hook cpufreq so that changes in frequency are reflected in the timebase. > Since the host updates guest time prior to putting vcpu to run, two > vcpus that start running at different times will have different system > values. > > Now if the vcpu that started running later probes the time first, > we'll se the time going backwards. A constant tsc rate is the only way > around > my limited mind sees around the problem (besides, obviously, _not_ > making the system time per-vcpu). > I tried disabling frequency scaling (rmmod acpi_cpufreq) but that didn't help my present problems. -- error compiling committee.c: too many arguments to function