From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock Date: Mon, 19 Apr 2010 09:19:38 -0700 Message-ID: <4BCC829A.6000803@goop.org> References: <1271356648-5108-1-git-send-email-glommer@redhat.com> <1271356648-5108-2-git-send-email-glommer@redhat.com> <4BC8CA52.4090703@goop.org> <20100419142624.GE14158@mothafucka.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, avi@redhat.com, Marcelo Tosatti , Zachary Amsden To: Glauber Costa Return-path: Received: from claw.goop.org ([74.207.240.146]:39200 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754975Ab0DSQTi (ORCPT ); Mon, 19 Apr 2010 12:19:38 -0400 In-Reply-To: <20100419142624.GE14158@mothafucka.localdomain> Sender: kvm-owner@vger.kernel.org List-ID: On 04/19/2010 07:26 AM, Glauber Costa wrote: >> Is the problem that the tscs are starting out of sync, or that they're >> drifting relative to each other over time? Do the problems become worse >> the longer the uptime? How large are the offsets we're talking about here? >> > The offsets usually seem pretty small, under a microsecond. So I don't think > it has anything to do with tscs starting out of sync. Specially because the > delta-based calculation has the exact purpose of handling that case. > So you think they're drifting out of sync from an initially synced state? If so, what would bound the drift? J