From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751974Ab1HXN7C (ORCPT ); Wed, 24 Aug 2011 09:59:02 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:50421 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750767Ab1HXN67 (ORCPT ); Wed, 24 Aug 2011 09:58:59 -0400 Date: Wed, 24 Aug 2011 15:58:55 +0200 From: Frederic Weisbecker To: Steevven1 Cc: linux-kernel@vger.kernel.org, Andrew Morton , Thomas Gleixner , Arjan van de Ven Subject: Re: Bug Report for Linux Kernel 3.x Message-ID: <20110824135852.GE23979@somewhere> References: <20110824001137.GA23979@somewhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (Please don't top-post) On Tue, Aug 23, 2011 at 08:21:50PM -0400, Steevven1 wrote: > QUICK NOTE - Thanks for replying directly to me as well as the mailing > list. I am NOT on that mailing list. Please continue to do this. > > That is correct about sparse irq. That was causing the first problem, > and solving that did in fact result in better power performance, but > it was apparently NOT the bulk of the problem. > > We still have no diagnosis at all for the apparently still-present > other (mystery) problem. Powertop now reports to me very low processor > wakeups (basically the same as the 2.6-series kernels), which > indicates to me that the problem is PROBABLY not related to processor > wakeups. I am by no means an expert. The top wakeup-causers with the > modified 3.0 kernel (no sparse irq) and an idle system are "[iwlagn] > " (wifi), "[i915] " (I don't know what this is), > and "[kernel scheduler] Load balancing tick" > > P-states/frequencies are handled about the same as with the 2.6 > kernels, so I don't see a problem there either. > > What else can I check? It seems like powertop is telling me nothing > about this mystery power drain. Well, if powertop has nothing to tell about that, I have no clue where to go. I'm adding more people in Cc in the hope they can be more helpful. > > > On Tue, Aug 23, 2011 at 8:11 PM, Frederic Weisbecker wrote: > > On Tue, Aug 23, 2011 at 07:19:35PM -0400, Steevven1 wrote: > >> Hello, > >> > >> I would like to report what myself and several others believe to be a > >> serious bug affecting all Linux kernels 3.0 and up, and none below 3.0 > >> (2.6.x and lower). > >> > >> One-sentence description: On certain hardware, the 3.x series kernels > >> drain a considerable amount more power than the 2.6-series kernels, up > >> to 40% more, even when idle. > >> > >> The specific hardware I have personally tested is a Lenovo ThinkPad > >> X220 with an Intel SandyBridge i7 2620M processor. We think that this > >> bug is POSSIBLY specific to this processor, or family of processors, > >> commonly used in notebooks. A complete thread of mine and others' > >> results, evidence, and troubleshooting process is located at: > >> http://ubuntuforums.org/showthread.php?t=1822629 > >> > >> We have tried several different 3.0 and 3.1-series kernels, all with > >> the same problems. One part of the problem was that the following > >> (revealed by powertop) was causing excessive processor wakeups > >> compared to the 2.6-series kernels: "[Rescheduling interrupts] >> IPI>" > >> > >> Someone much more advanced than I figured out how to eliminate this > >> problem and recompiled the kernel (which he posted in the thread I > >> linked to previously), but power usage is still improved only > >> slightly, nowhere near kernel 2.6 levels. > >> > >> There is a lot more information I could give you here, but all of it > >> is contained within the thread I linked to. If you have any specific > >> questions, I will answer as quickly as possible. > >> > >> Thanks a lot for your assistance. Please confirm that you received this email. > >> > >> Steven Keys! > > > > Hi Steve, > > > > > > You said the problem with rescheduling interrupt disappeared but you > > haven't said why. After reading the thread it seems it was about > > Sparse irq config beeing enabled? And that disappeared after > > sparse irq got disabled? > > > > If so that looks like a first bug. > > > > Also now that you don't see that problem anymore but still > > a problem with power consumption, what does powertop report to > > you? > > > > Thanks. > >