From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: system time Date: Thu, 27 Sep 2007 12:07:20 +0200 Message-ID: <46FB80D8.7060308@qumranet.com> References: <46FA5CB2.70206@bppiac.hu> <46FB7B0B.5050907@qumranet.com> <46FB7AA6.5050708@bppiac.hu> <46FB7DFF.6020102@qumranet.com> <46FB7CFB.7020607@bppiac.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel To: Farkas Levente Return-path: In-Reply-To: <46FB7CFB.7020607-lWVWdrzSO4GHXe+LvDLADg@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 Farkas Levente wrote: > Avi Kivity wrote: > >> Farkas Levente wrote: >> >>> Avi Kivity wrote: >>> >>> >>>> Haydn Solomon wrote: >>>> >>>> >>>>> I know I'm not crazy.. now my host and guest clocks are in sync. I'll >>>>> leave the guest running for a while and see if it eventually goes >>>>> ahead of host. >>>>> >>>>> >>>>> >>>> Please do this both with and without -no-kvm-irqchip. The code paths >>>> are very different. >>>> >>>> >>> the simple question does all the guest must be the same system time as >>> the host? and if it's not the case then it's a bug? or it can happened >>> with reason? >>> >>> >> Difficult to say. I think that some drift is inevitable as the guest >> and host will calibrate differently. >> > > in the current version or even in long term? > It's a fundamental issue due to how PCs do time. They run a calibration look during bootup, and if that's not 100% accurate, dirft will occur. For the long term the solution is paravirtualized time. > this means it's better to run ntpd on all guests even if it's running on > the host:-(( > I think there are issues with running ntp on the guest due to tsc being very inaccurate on virtualized guests. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/