Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756153Ab2KNBgZ (ORCPT ); Tue, 13 Nov 2012 20:36:25 -0500 Received: from e7.ny.us.ibm.com ([32.97.182.137]:45143 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756063Ab2KNBgX (ORCPT ); Tue, 13 Nov 2012 20:36:23 -0500 Date: Tue, 13 Nov 2012 17:34:59 -0800 From: "Paul E. McKenney" To: Jacob Pan Cc: Arjan van de Ven , Linux PM , LKML , Rafael Wysocki , Len Brown , Thomas Gleixner , "H. Peter Anvin" , Ingo Molnar , Zhang Rui , Rob Landley Subject: Re: [PATCH 3/3] PM: Introduce Intel PowerClamp Driver Message-ID: <20121114013459.GS2489@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1352757831-5202-1-git-send-email-jacob.jun.pan@linux.intel.com> <1352757831-5202-4-git-send-email-jacob.jun.pan@linux.intel.com> <20121113211602.GA30150@linux.vnet.ibm.com> <20121113133922.47144a50@chromoly> <20121113222350.GH2489@linux.vnet.ibm.com> <50A2CD77.7000403@linux.intel.com> <20121114000259.GK2489@linux.vnet.ibm.com> <50A2E116.8000400@linux.intel.com> <20121113171450.3657290c@chromoly> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121113171450.3657290c@chromoly> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12111401-5806-0000-0000-00001BBE7BD5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1109 Lines: 27 On Tue, Nov 13, 2012 at 05:14:50PM -0800, Jacob Pan wrote: > On Tue, 13 Nov 2012 16:08:54 -0800 > Arjan van de Ven wrote: > > > > I think I know, but I feel the need to ask anyway. Why not tell > > > RCU about the clamping? > > > > I don't mind telling RCU, but what cannot happen is a bunch of CPU > > time suddenly getting used (since that is the opposite of what is > > needed at the specific point in time of going idle) Another round of RCU_FAST_NO_HZ rework, you are asking for? ;-) > Another reason is my observation that there are some assumptions/checks > to make sure only idle thread can tell rcu it is idle. Is it ok to > extend that to other kthreads? If you are only having the system take 6-millisecond "vacations", probably best to try it as it is and fix specific problems if/when they arise. Thanx, Paul -- 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/