Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756078Ab2KNAJJ (ORCPT ); Tue, 13 Nov 2012 19:09:09 -0500 Received: from mga11.intel.com ([192.55.52.93]:49865 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756039Ab2KNAJH (ORCPT ); Tue, 13 Nov 2012 19:09:07 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.83,768,1352102400"; d="scan'208";a="248697475" Message-ID: <50A2E116.8000400@linux.intel.com> Date: Tue, 13 Nov 2012 16:08:54 -0800 From: Arjan van de Ven User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20121026 Thunderbird/16.0.2 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: Jacob Pan , 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 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> In-Reply-To: <20121114000259.GK2489@linux.vnet.ibm.com> X-Enigmail-Version: 1.4.5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1146 Lines: 28 > > OK, so the point of clamping all sockets simultaneously is to be able > to power down the electronics surrounding the sockets as well as the > sockets themselves? yup; memory can go to self refresh etc etc >If all you cared about was the individual sockets, > I don't see why you couldn't power the sockets down individually rather > than in sync with each other. the hardware that this driver supports does not support powering down sockets individually. (since the memory controllers are part of the "socket"... it would increase latency etc etc, and likely wreak havoc with the cache coherency protocols) > 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) -- 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/