Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753201AbZIFF1W (ORCPT ); Sun, 6 Sep 2009 01:27:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752280AbZIFF1V (ORCPT ); Sun, 6 Sep 2009 01:27:21 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:52421 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752160AbZIFF1V (ORCPT ); Sun, 6 Sep 2009 01:27:21 -0400 Date: Sun, 6 Sep 2009 07:27:17 +0200 From: Pavel Machek To: Norbert van Bolhuis Cc: linux-kernel@vger.kernel.org, Thomas Gleixner Subject: Re: PROBLEM: CONFIG_NO_HZ could cause software timeouts Message-ID: <20090906052717.GC1324@ucw.cz> References: <4A9F9F64.5080305@aimvalley.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A9F9F64.5080305@aimvalley.nl> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 785 Lines: 18 On Thu 2009-09-03 12:50:12, Norbert van Bolhuis wrote: > > The problem occurs when e.g. drivers use time_after(jiffes, timeout). > > CONFIG_NO_HZ could make jiffies advance by more than 1. > This is done by: tick_nohz_update_jiffies->tick_do_update_jiffies64->do_timer jiffies really should be up-to-date as long as you are running anything else than idle loop. If not, that's a bug ... and nasty one. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/