From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752596AbXCECar (ORCPT ); Sun, 4 Mar 2007 21:30:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752595AbXCECar (ORCPT ); Sun, 4 Mar 2007 21:30:47 -0500 Received: from smtp.osdl.org ([65.172.181.24]:56520 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752596AbXCECap (ORCPT ); Sun, 4 Mar 2007 21:30:45 -0500 Date: Sun, 4 Mar 2007 18:26:19 -0800 From: Andrew Morton To: Adrian Bunk Cc: Linus Torvalds , Linux Kernel Mailing List , Sid Boyce , Pavel Machek , Marcel Holtmann , linux-pm@lists.osdl.org, maxk@qualcomm.com, bluez-devel@lists.sourceforge.net, Mark Lord , Greg KH , Matt Mackall , Johannes Berg , Albert Hopkins , Ayaz Abdulla , Jeff Garzik , netdev@vger.kernel.org Subject: Re: [1/6] 2.6.21-rc2: known regressions Message-Id: <20070304182619.6110bd74.akpm@linux-foundation.org> In-Reply-To: <20070305015031.GF3441@stusta.de> References: <20070305015031.GF3441@stusta.de> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 5 Mar 2007 02:50:31 +0100 Adrian Bunk wrote: > This email lists some known regressions in 2.6.21-rc2 compared to 2.6.20 > that are not yet fixed in Linus' tree. We seem to have broken an unusually large amount of stuff this time. partial post-mortem: - The ACPICA merge landed in -mm super-late: basically it was in mainline a week afterwards and saw only a single -mm release. Part of the reason for this short period in -mm was that ACPICA had its paws all over x86_64 code and conflicted badly with significant changes in the x86_64 tree. That happens sometimes. But when it does, the mess lands in my lap rather than in the laps of the perpetrators. Lesson: keep the code well-factored so that different subsystems don't soil each others' kennels. - The hrtimers/dynticks stuff is simply hard: timekeeping, low-level x86, even APICs. These are areas in which things break a lot, so churning it was inevitably going to cause problems. Lesson: none, I think. Low-level x86 support is just hard, and changing it breaks things. So that accounts for _some_ of the damage, but I wonder if there's more to it than that.