Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752749AbZJMMrI (ORCPT ); Tue, 13 Oct 2009 08:47:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751294AbZJMMrH (ORCPT ); Tue, 13 Oct 2009 08:47:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40329 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750862AbZJMMrH (ORCPT ); Tue, 13 Oct 2009 08:47:07 -0400 Date: Tue, 13 Oct 2009 09:46:38 -0300 From: Glauber Costa To: Avi Kivity Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] allow userspace to adjust kvmclock offset Message-ID: <20091013124638.GC8092@mothafucka.localdomain> References: <1254849896-3947-1-git-send-email-glommer@redhat.com> <4AD2EE86.50807@redhat.com> <20091013122828.GZ8092@mothafucka.localdomain> <4AD4730C.9010305@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AD4730C.9010305@redhat.com> X-ChuckNorris: True User-Agent: Jack Bauer Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 769 Lines: 21 On Tue, Oct 13, 2009 at 03:31:08PM +0300, Avi Kivity wrote: > On 10/13/2009 03:28 PM, Glauber Costa wrote: >> >>> Do we want an absolute or relative adjustment? >>> >> What exactly do you mean? >> > > Absolute adjustment: clock = t > Relative adjustment: clock += t The delta is absolute, but the adjustment in the clock is relative. So we pick the difference between what userspace is passing us and what we currently have, then relatively adds up so we can make sure we won't go back or suffer a too big skew. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/