From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759105Ab0E1Rn4 (ORCPT ); Fri, 28 May 2010 13:43:56 -0400 Received: from vms173009pub.verizon.net ([206.46.173.9]:63262 "EHLO vms173009pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756739Ab0E1Rny (ORCPT ); Fri, 28 May 2010 13:43:54 -0400 Date: Fri, 28 May 2010 13:43:35 -0400 (EDT) From: Len Brown X-X-Sender: lenb@localhost.localdomain To: Chase Douglas Cc: x86@kernel.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Len Brown Subject: Re: [PATCH 8/8] intel_idle: create a native cpuidle driver for select intel processors In-reply-to: <1275059380.5612.60.camel@cndougla-ubuntu> Message-id: References: <1274928151-30919-1-git-send-email-lenb@kernel.org> <198450ec1600d9a7f55270dd4d44d6b55bc5b184.1274926772.git.len.brown@intel.com> <1275013933.2312.7.camel@cndougla-ubuntu> <1275059380.5612.60.camel@cndougla-ubuntu> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 28 May 2010, Chase Douglas wrote: > 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! Atom C4 works in the current driver in the git tree -- test it now! cheers, -Len