From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755288AbbERXpx (ORCPT ); Mon, 18 May 2015 19:45:53 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:24480 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755025AbbERXpt (ORCPT ); Mon, 18 May 2015 19:45:49 -0400 Message-ID: <555A79A5.608@oracle.com> Date: Mon, 18 May 2015 19:45:41 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Marcelo Tosatti CC: KVM General , LKML , Paolo Bonzini , lcapitulino@redhat.com Subject: Re: kvm: odd time values since "kvmclock: set scheduler clock stable" References: <55528A04.2060404@oracle.com> <20150518223936.GA4486@amt.cnet> In-Reply-To: <20150518223936.GA4486@amt.cnet> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/18/2015 06:39 PM, Marcelo Tosatti wrote: > On Tue, May 12, 2015 at 07:17:24PM -0400, Sasha Levin wrote: >> Hi all, >> >> I'm seeing odd jump in time values during boot of a KVM guest: >> >> [...] >> [ 0.000000] tsc: Detected 2260.998 MHz processor >> [3376355.247558] Calibrating delay loop (skipped) preset value.. >> [...] >> >> I've bisected it to: > > Paolo, Sasha, > > Although this might seem undesirable, there is no requirement > for sched_clock to initialize at 0: > > " > * > * There is no strict promise about the base, although it tends to start > * at 0 on boot (but people really shouldn't rely on that). > * > " > > Sasha, are you seeing any problem other than the apparent time jump? Nope, but I've looked at it again and it seems that it jumps to the host's clock (that is, in the example above the 3376355 value was the host's clock value). Thanks, Sasha