From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761987AbXKHSDF (ORCPT ); Thu, 8 Nov 2007 13:03:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761244AbXKHSCq (ORCPT ); Thu, 8 Nov 2007 13:02:46 -0500 Received: from smtp2.linux-foundation.org ([207.189.120.14]:60355 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761215AbXKHSCp (ORCPT ); Thu, 8 Nov 2007 13:02:45 -0500 Date: Thu, 8 Nov 2007 10:02:12 -0800 From: Andrew Morton To: Valdis.Kletnieks@vt.edu Cc: mgross@linux.intel.com, linux-kernel@vger.kernel.org Subject: Re: 2.6.23-mm1 breaks C-state support on Intel T7200 x86_64 Message-Id: <20071108100212.0cbff318.akpm@linux-foundation.org> In-Reply-To: <3624.1194542384@turing-police.cc.vt.edu> References: <3624.1194542384@turing-police.cc.vt.edu> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.19; i686-pc-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 Thu, 08 Nov 2007 12:19:44 -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. > > 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 > > 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? > That's a great report, thanks. Over to you, Mark ;) btw, I also have a note here that these patches caused Rafael to see an smp_call_function() inside local_irq_save(). Did that get fixed?