Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753860Ab1FJQzf (ORCPT ); Fri, 10 Jun 2011 12:55:35 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:55828 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751324Ab1FJQzd (ORCPT ); Fri, 10 Jun 2011 12:55:33 -0400 Date: Fri, 10 Jun 2011 09:55:29 -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: <20110610165529.GC2230@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110610155954.GA25774@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: 1344 Lines: 28 On Fri, Jun 10, 2011 at 04:59:54PM +0100, Matthew Garrett wrote: > On Fri, Jun 10, 2011 at 08:11:21AM -0700, Paul E. McKenney wrote: > > > Of course, on a server, you could get similar results by having a very > > large amount of memory (say 256GB) and a workload that needed all the > > memory only occasionally for short periods, but could get by with much > > less (say 8GB) the rest of the time. I have no idea whether or not > > anyone actually has such a system. > > For the server case, the low hanging fruit would seem to be > finer-grained self-refresh. At best we seem to be able to do that on a > per-CPU socket basis right now. The difference between active and > self-refresh would seem to be much larger than the difference between > self-refresh and powered down. By "finer-grained self-refresh" you mean turning off refresh for banks of memory that are not being used, right? If so, this is supported by the memory-regions support provided, at least assuming that the regions can be aligned with the self-refresh boundaries. Or am I missing your point? 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/