From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753188AbZHFB67 (ORCPT ); Wed, 5 Aug 2009 21:58:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751142AbZHFB66 (ORCPT ); Wed, 5 Aug 2009 21:58:58 -0400 Received: from mga01.intel.com ([192.55.52.88]:15635 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750825AbZHFB65 (ORCPT ); Wed, 5 Aug 2009 21:58:57 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.43,331,1246863600"; d="scan'208";a="714328993" Date: Thu, 6 Aug 2009 09:58:55 +0800 From: Shaohua Li To: Gautham R Shenoy Cc: Joel Schopp , "Brown, Len" , Peter Zijlstra , Balbir Singh , "Pallipadi, Venkatesh" , Benjamin Herrenschmidt , Ingo Molnar , Vaidyanathan Srinivasan , Dipankar Sarma , "Darrick J. Wong" , "linuxppc-dev@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 0/3] cpu: idle state framework for offline CPUs. Message-ID: <20090806015855.GA20596@sli10-desk.sh.intel.com> References: <20090805142311.553.78286.stgit@sofia.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090805142311.553.78286.stgit@sofia.in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wed, Aug 05, 2009 at 10:25:53PM +0800, Gautham R Shenoy wrote: > In this patch-series, we propose to extend the CPU-Hotplug infrastructure > and allow the system administrator to choose the desired state the CPU should > go to when it is offlined. We think this approach addresses the concerns about > determinism as well as transparency, since CPU-Hotplug already provides > notification mechanism which the userspace can listen to for any change > in the configuration and correspondingly readjust any previously set > cpu-affinities. Peter dislikes any approach (including cpuhotplug) which breaks userspace policy, even userspace can get a notification. > Also, approaches such as [1] can make use of this > extended infrastructure instead of putting the CPU to an arbitrary C-state > when it is offlined, thereby providing the system administrator a rope to hang > himself with should he feel the need to do so. I didn't see the reason why administrator needs to know which state offline cpu should stay. Don't know about powerpc side, but in x86 side, it appears deepest C-state is already preferred. Thanks, Shaohua