Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753152AbZIYIx7 (ORCPT ); Fri, 25 Sep 2009 04:53:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752935AbZIYIx7 (ORCPT ); Fri, 25 Sep 2009 04:53:59 -0400 Received: from viefep17-int.chello.at ([62.179.121.37]:59711 "EHLO viefep17-int.chello.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751814AbZIYIx6 (ORCPT ); Fri, 25 Sep 2009 04:53:58 -0400 X-SourceIP: 213.93.53.227 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. From: Peter Zijlstra To: svaidy@linux.vnet.ibm.com Cc: Arjan van de Ven , arun@linux.vnet.ibm.com, Len Brown , Joel Schopp , Benjamin Herrenschmidt , Paul Mackerras , Ingo Molnar , 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 In-Reply-To: <20090925070623.GH8595@dirshya.in.ibm.com> References: <20090922112526.GA7788@linux.vnet.ibm.com> <20090924051238.GA5963@linux.vnet.ibm.com> <20090924142228.5a2ddf59@infradead.org> <20090925070623.GH8595@dirshya.in.ibm.com> Content-Type: text/plain Date: Fri, 25 Sep 2009 10:54:24 +0200 Message-Id: <1253868864.10287.3.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1634 Lines: 44 On Fri, 2009-09-25 at 12:36 +0530, Vaidyanathan Srinivasan wrote: > * Arjan van de Ven [2009-09-24 14:22:28]: > > > 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 > > So we will need to keep the per-cpu registration as of now because we > may have such buggy BIOS in the field and we don't want the cpuidle > framework to malfunction there. If the BIOS doesn't mention a certain C state on a cpu, and you try to set it anyway, does that go boom? This whole per-cpu registration thing is horridly ugly, can't you have a per-cpu C state exception mask and leave it at that -- if its really needed? -- 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/