From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755337Ab3AUXDn (ORCPT ); Mon, 21 Jan 2013 18:03:43 -0500 Received: from hydra.sisk.pl ([212.160.235.94]:48618 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752973Ab3AUXDm (ORCPT ); Mon, 21 Jan 2013 18:03:42 -0500 From: "Rafael J. Wysocki" To: Olivier Doucet Cc: Borislav Petkov , linux-kernel@vger.kernel.org Subject: Re: Performance issue since 3.2.6 Date: Tue, 22 Jan 2013 00:09:41 +0100 Message-ID: <2048745.M7CAe2g1gj@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.8.0-rc4; KDE/4.9.5; x86_64; ; ) In-Reply-To: References: <18379918.sbmR7uiKVn@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday, January 21, 2013 11:57:06 PM Olivier Doucet wrote: > Good evening, > > >> I'll try to track this commit. > > > > Thanks a lot! > > I failed to find a working version today with CONFIG_PM=y > (tested 3.2.6, 3.2.5, 3.2.0, 3.0.1, 2.6.32.8). I'll try older kernels tomorrow. I don't think that's necessary. It looks like CONFIG_PM=y has never really worked for you, but you wasn't aware of that. > I'm very sceptical now : how can a bug with such a big impact (25% > performance drop) can survive for so many years, with no one seeing it > ? > Good point is that benchmark can be easily done (it took less than an > hour to test a new version). If you have patches to be tested, feel > free to ask :) > > In the meanwhile, do you think I can compile a working 3.7 kernel ? > Maybe by activating / deactivating specific options ? I'm really not sure. It looks like CONFIG_PM makes PM QoS affect cpuidle for you in a wrong way, so to speak. I suppose it's time to look into the code and see what makes the difference. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.