Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757442Ab1FJRwy (ORCPT ); Fri, 10 Jun 2011 13:52:54 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:57395 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750871Ab1FJRww (ORCPT ); Fri, 10 Jun 2011 13:52:52 -0400 Date: Fri, 10 Jun 2011 10:52:48 -0700 From: "Paul E. McKenney" To: Matthew Garrett Cc: Kyungmin Park , Andrew Morton , Ankita Garg , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, svaidy@linux.vnet.ibm.com, thomas.abraham@linaro.org Subject: Re: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management Message-ID: <20110610175248.GF2230@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1306499498-14263-1-git-send-email-ankita@in.ibm.com> <20110528005640.9076c0b1.akpm@linux-foundation.org> <20110609185259.GA29287@linux.vnet.ibm.com> <20110610151121.GA2230@linux.vnet.ibm.com> <20110610155954.GA25774@srcf.ucam.org> <20110610165529.GC2230@linux.vnet.ibm.com> <20110610170535.GC25774@srcf.ucam.org> <20110610171939.GE2230@linux.vnet.ibm.com> <20110610172307.GA27630@srcf.ucam.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110610172307.GA27630@srcf.ucam.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1300 Lines: 26 On Fri, Jun 10, 2011 at 06:23:07PM +0100, Matthew Garrett wrote: > On Fri, Jun 10, 2011 at 10:19:39AM -0700, Paul E. McKenney wrote: > > On Fri, Jun 10, 2011 at 06:05:35PM +0100, Matthew Garrett wrote: > > > I mean at the hardware level. As far as I know, the best we can do at > > > the moment is to put an entire node into self refresh when the CPU hits > > > package C6. > > > > But this depends on the type of system and CPU family, right? If you > > can say, which hardware are you thinking of? (I am thinking of ARM.) > > I haven't seen too many ARM servers with 256GB of RAM :) I'm mostly > looking at this from an x86 perspective. But I have seen ARM embedded systems with CPU power consumption in the milliwatt range, which greatly reduces the amount of RAM required to get significant power savings from this approach. Three orders of magnitude less CPU power consumption translates (roughly) to three orders of magnitude less memory required -- and embedded devices with more than 256MB of memory are quite common. 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/