From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932796Ab0E1PJx (ORCPT ); Fri, 28 May 2010 11:09:53 -0400 Received: from adelie.canonical.com ([91.189.90.139]:49590 "EHLO adelie.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932135Ab0E1PJv (ORCPT ); Fri, 28 May 2010 11:09:51 -0400 Subject: Re: [PATCH 8/8] intel_idle: create a native cpuidle driver for select intel processors From: Chase Douglas To: Len Brown Cc: x86@kernel.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Len Brown In-Reply-To: References: <1274928151-30919-1-git-send-email-lenb@kernel.org> <198450ec1600d9a7f55270dd4d44d6b55bc5b184.1274926772.git.len.brown@intel.com> <1275013933.2312.7.camel@cndougla-ubuntu> Content-Type: text/plain; charset="UTF-8" Date: Fri, 28 May 2010 11:09:40 -0400 Message-ID: <1275059380.5612.60.camel@cndougla-ubuntu> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-05-28 at 00:16 -0400, Len Brown wrote: > > I see that you have updated this code in your tree to disable C4 and C6 > > on atom. This has piqued my curiosity. I've now seen 2 atom netbooks > > from different OEMs that hide C4 when you plug the power in. After the > > first machine I thought, "must be a BIOS/ACPI bug," but now I'm > > beginning to wonder if there's some issue with atom C4 states? That's > > beside the fact that I've not seen C6 on either machine at all. Do you > > have any insight? > > The reasoning behind ACPI taking deep C-states away > when on AC is the assumption that users on AC > care more about low latency and high performance > than they care about power savings, heat, and noise. Maybe they forgot that a netbook is still a *lap*top when they did this, cause I can't keep mine on my lap when it's plugged in :). The CPU idles at 60 centigrade when powered on, and drops to a manageable 30-ish centigrade when running on battery. > So my intent is to give Linux control over this decision, > via PM_QOS or otherwise. At the moment C4 is commented out > because when i first tested it failed the lapic timer workaround. I am looking forward to testing out these changes on my netbook once this issue get sorted out! -- Chase