From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id B2AAE6B0012 for ; Fri, 10 Jun 2011 13:52:51 -0400 (EDT) Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by e2.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p5AHWSMi019801 for ; Fri, 10 Jun 2011 13:32:28 -0400 Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p5AHqnUi121618 for ; Fri, 10 Jun 2011 13:52:49 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p5AHqnqi016180 for ; Fri, 10 Jun 2011 13:52:49 -0400 Date: Fri, 10 Jun 2011 10:52:48 -0700 From: "Paul E. McKenney" 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org