From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762206AbXKHSI6 (ORCPT ); Thu, 8 Nov 2007 13:08:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761140AbXKHSIu (ORCPT ); Thu, 8 Nov 2007 13:08:50 -0500 Received: from mga06.intel.com ([134.134.136.21]:23310 "EHLO orsmga101.jf.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1760662AbXKHSIt (ORCPT ); Thu, 8 Nov 2007 13:08:49 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.21,390,1188802800"; d="scan'208";a="266114649" Date: Thu, 8 Nov 2007 10:07:39 -0800 From: Mark Gross To: Valdis.Kletnieks@vt.edu Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: 2.6.23-mm1 breaks C-state support on Intel T7200 x86_64 Message-ID: <20071108180739.GA5062@linux.intel.com> Reply-To: mgross@linux.intel.com References: <3624.1194542384@turing-police.cc.vt.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3624.1194542384@turing-police.cc.vt.edu> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 08, 2007 at 12:19:44PM -0500, Valdis.Kletnieks@vt.edu wrote: > (Sorry for not reporting this sooner - I haven't been running off battery > much in the last 3 weeks, so I didn't notice it till now...) > > Dell Latitude D820 laptop, T7200 Core2 Duo CPU, x86_64 kernel. > > As reported by 'powertop' on a basically idle machine: > > 2.6.23-mm1: > > Cn Avg residency P-states (frequencies) > C0 (cpu running) (100.0%) 2.00 Ghz 0.8% > C1 0.0ms ( 0.0%) 1.67 Ghz 0.0% > C2 0.0ms ( 0.0%) 1333 Mhz 0.0% > C3 0.0ms ( 0.0%) 1000 Mhz 99.2% > > 2.6.23-rc8-mm2: > > Cn Avg residency P-states (frequencies) > C0 (cpu running) ( 0.3%) 2.00 Ghz 0.0% > C1 0.0ms ( 0.0%) 1.67 Ghz 0.0% > C2 0.0ms ( 0.0%) 1333 Mhz 0.0% > C3 31.5ms (99.7%) 1000 Mhz 100.0% > > In addition, the ACPI power estimate reported about 25 watts for 23-mm1, > but only 21 watts for -rc8-mm2, a significant regression. well, thats because you burn less watts if you get into C3. > > I bisected this down to this set of patches: > > pm-qos-infrastructure-and-interface.patch > pm-qos-infrastructure-and-interface-fix.patch > pm-qos-infrastructure-and-interface-vs-git-acpi.patch > pm-qos-infrastructure-and-interface-vs-git-acpi-2.patch > latencyc-use-qos-infrastructure.patch yipes! I'll look at it right away. It looks like an integration issue with CPU-IDLE patches (those control the C-state entry). I'll get it fixed up. > > The patch says: > > To register the default pm_qos target for the specific parameter, the > process must open one of /dev/[cpu_dma_latency, network_latency, > network_throughput] > > As long as the device node is held open that process has a registered > requirement on the parameter. The name of the requirement is > "process_" derived from the current->pid from within the open system > call. > > I shouldn't have to have a process open a /dev/file, write a number, and then > stay around forever so the file doesn't close in order to get the same behavior > I was getting by default before. What needs to happen to get this to not > be a behavior regression/change? > you won't have such a process (at least I highly doubt you do) I need to fix this. Thanks for taking the time to bisect it and reporting it to me! --mgross