From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: why guests show "Clocksource tsc unstable" on bootup? Date: Sun, 15 Mar 2009 14:56:45 +0200 Message-ID: <49BCFB0D.2000901@redhat.com> References: <49B5050B.9050204@wpkg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: "kvm@vger.kernel.org" To: Tomasz Chmielewski Return-path: Received: from mx2.redhat.com ([66.187.237.31]:34771 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbZCOM4v (ORCPT ); Sun, 15 Mar 2009 08:56:51 -0400 In-Reply-To: <49B5050B.9050204@wpkg.org> Sender: kvm-owner@vger.kernel.org List-ID: Tomasz Chmielewski wrote: > Why do my guests show "Clocksource tsc unstable" on bootup? > Linux expects the tsc to be monotonic and to have a 1:1 correspondence with real time, which isn't easy to achieve with virtualization. > dmesg shows that kvm-clock was set as the primary cpu clock. > Yet a bit later kernel says "Clocksource tsc unstable". > > Is it something to worry about, or perhaps calculating tsc is hardcoded? > And as such, will be always checked? > Or, is it host CPU related? > > [ 0.000000] kvm-clock: cpu 0, msr 0:3baf81, boot clock > [ 0.000000] kvm-clock: cpu 0, msr 0:1208f81, primary cpu clock > [ 0.000000] Kernel command line: root=/dev/vda1 ro quiet > clocksource=kvm-clock > [ 1.253602] rtc_cmos 00:01: setting system clock to 2009-03-09 > 11:41:30 UTC (1236598890) > [ 41.500623] Clocksource tsc unstable (delta = -153498948 ns) > > What host cpu and kvm version are you using? -- error compiling committee.c: too many arguments to function