Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756534AbYFCTwy (ORCPT ); Tue, 3 Jun 2008 15:52:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754396AbYFCTwo (ORCPT ); Tue, 3 Jun 2008 15:52:44 -0400 Received: from 41-052.adsl.zetnet.co.uk ([194.247.41.52]:45472 "EHLO mail.esperi.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754164AbYFCTwn (ORCPT ); Tue, 3 Jun 2008 15:52:43 -0400 To: Daniel Hazelton Cc: Andrew Morton , Jeff Dike , akpm@linuxfoundation.org, linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net Subject: Re: [PATCH 1/6] UML - Deal with host time going backwards References: <20080603190235.GA9511@c2.user-mode-linux.org> <20080603123211.e129c222.akpm@linux-foundation.org> <200806031543.56864.dhazelton@enter.net> From: Nix Emacs: an inspiring example of form following function... to Hell. Date: Tue, 03 Jun 2008 20:52:18 +0100 In-Reply-To: <200806031543.56864.dhazelton@enter.net> (Daniel Hazelton's message of "Tue, 3 Jun 2008 15:43:56 -0400") Message-ID: <878wxmfg99.fsf@hades.wkstn.nix> User-Agent: Gnus/5.1008 (Gnus v5.10.8) XEmacs/21.5-b28 (linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-DCC--Metrics: hades 1114; Body=6 Fuz1=6 Fuz2=6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1303 Lines: 33 On 3 Jun 2008, Daniel Hazelton said: > On Tuesday 03 June 2008 03:32:11 pm Andrew Morton wrote: >> On Tue, 3 Jun 2008 15:02:35 -0400 >> >> Jeff Dike wrote: >> > Protection against the host's time going backwards - keep track of the >> > time at the last tick and if it's greater than the current time, keep >> > time stopped until the host catches up. >> >> Strange. What would cause the host's time (or at least UML's perception >> of it) to go backwards? > > A wild guess would be that the UML process is running "fast" at some point and > its expectation of the host's time is skewed forward because of that. Quite so. Simply running ntp on the host (in slew-only mode, no less!) can cause this. > Another possibility is that the hosts clock got reset between the times UML > has checked it and the correction was a negative one. That too. -- `If you are having a "ua luea luea le ua le" kind of day, I can only assume that you are doing no work due [to] incapacitating nausea caused by numerous lazy demons.' --- Frossie -- 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/