Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752584AbZIXMZu (ORCPT ); Thu, 24 Sep 2009 08:25:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752230AbZIXMZt (ORCPT ); Thu, 24 Sep 2009 08:25:49 -0400 Received: from casper.infradead.org ([85.118.1.10]:34123 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751676AbZIXMZs (ORCPT ); Thu, 24 Sep 2009 08:25:48 -0400 Date: Thu, 24 Sep 2009 14:22:28 +0200 From: Arjan van de Ven To: arun@linux.vnet.ibm.com Cc: Len Brown , Peter Zijlstra , Joel Schopp , Benjamin Herrenschmidt , Paul Mackerras , Ingo Molnar , Vaidyanathan Srinivasan , Dipankar Sarma , Balbir Singh , Gautham R Shenoy , Shaohua Li , Venkatesh Pallipadi , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org Subject: Re: [v6 PATCH 0/7]: cpuidle/x86/POWER: Cleanup idle power management code in x86, cleanup drivers/cpuidle/cpuidle.c and introduce cpuidle to POWER. Message-ID: <20090924142228.5a2ddf59@infradead.org> In-Reply-To: <20090924051238.GA5963@linux.vnet.ibm.com> References: <20090922112526.GA7788@linux.vnet.ibm.com> <20090924051238.GA5963@linux.vnet.ibm.com> Organization: Intel X-Mailer: Claws Mail 3.7.2 (GTK+ 2.14.7; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1121 Lines: 34 On Thu, 24 Sep 2009 10:42:41 +0530 Arun R Bharadwaj wrote: > * Arun R Bharadwaj [2009-09-22 16:55:27]: > > Hi Len, (or other acpi folks), > > I had a question regarding ACPI-cpuidle interaction in the current > implementation. > > Currently, every cpu (i.e. acpi_processor) registers to cpuidle as > a cpuidle_device. So every cpu has to go through the process of > setting up the idle states and then registering as a cpuidle device. > > What exactly is the reason behind this? > technically a BIOS can opt to give you C states via ACPI on some cpus, but not on others. in practice when this happens it tends to be a bug.. but it's technically a valid configuration -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/