From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id 899386B0012 for ; Thu, 16 Jun 2011 05:19:50 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 57BD93EE0C0 for ; Thu, 16 Jun 2011 18:19:47 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 39D3645DE72 for ; Thu, 16 Jun 2011 18:19:47 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 13FD845DE6F for ; Thu, 16 Jun 2011 18:19:47 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id EAEF81DB8042 for ; Thu, 16 Jun 2011 18:19:46 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.240.81.146]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id B5ECC1DB803E for ; Thu, 16 Jun 2011 18:19:46 +0900 (JST) Date: Thu, 16 Jun 2011 18:12:51 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management Message-Id: <20110616181251.caf484b6.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110616042044.GA28563@in.ibm.com> References: <1306499498-14263-1-git-send-email-ankita@in.ibm.com> <20110613134701.2b23b8d8.kamezawa.hiroyu@jp.fujitsu.com> <20110616042044.GA28563@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Ankita Garg Cc: 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 Thu, 16 Jun 2011 09:50:44 +0530 Ankita Garg wrote: > Hi, > > On Mon, Jun 13, 2011 at 01:47:01PM +0900, KAMEZAWA Hiroyuki wrote: > > On Fri, 27 May 2011 18:01:28 +0530 > > Ankita Garg wrote: > > > > > Hi, > > > > > > > I'm sorry if you've answered already. > > > > Is memory hotplug is too bad and cannot be enhanced for this purpose ? > > > > I wonder > > - make section-size smaller (IIUC, IBM's system has 16MB section size) > > > > - add per section statistics > > > > - add a kind of balloon driver which does software memory offline > > (which means making a contiguous chunk of free pages of section_size > > by page migration) in background with regard to memory usage statistics. > > If system says "need more memory!", balloon driver can online pages. > > > > can work for your purpose. It can allow you page isolatation and > > controls in 16MB unit. If you need whole rework of memory hotplug, I think > > it's better to rewrite memory hotplug, too. > > > > Interesting idea, but a few issues - > > - Correctly predicting memory pressure is difficult and thereby being > able to online the required pages at the right time could be a > challenge But it will be required for your purpose, anyway. Isn't it ? > - Memory hotplug is a heavy operation, so the overhead involved may be > high soft-offline of small amount of pages will not very heavy. compaction and cma patches use the same kind of logic. > - Powering off memory is just one of the ways in which memory power could > be saved. The platform can also dynamically transition areas of memory > into a content-preserving lower power state if it is not referenced > for a pre-defined threshold of time. In such a case, we would need a > mechanism to soft offline the pages - i.e, no new allocations to be > directed to that memory > Hmm, sounds like a similar idea of CleanCache ? Reusing section is much easier than adding new one.., I think. Thanks, -Kame -- 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