From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id BD3216B0012 for ; Sun, 19 Jun 2011 20:00:11 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 183663EE0C1 for ; Mon, 20 Jun 2011 09:00:07 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id D11FA45DE97 for ; Mon, 20 Jun 2011 09:00:06 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id AEB8845DE67 for ; Mon, 20 Jun 2011 09:00:06 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 8B35A1DB803C for ; Mon, 20 Jun 2011 09:00:06 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.240.81.134]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 3899A1DB804E for ; Mon, 20 Jun 2011 09:00:06 +0900 (JST) Date: Mon, 20 Jun 2011 08:53:07 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management Message-Id: <20110620085307.76e16c8f.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110617152845.GA13574@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> <20110616181251.caf484b6.kamezawa.hiroyu@jp.fujitsu.com> <20110617152845.GA13574@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 Fri, 17 Jun 2011 20:58:45 +0530 Ankita Garg wrote: > Hi, > > On Thu, Jun 16, 2011 at 06:12:51PM +0900, KAMEZAWA Hiroyuki wrote: > > 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. > > > > But sections do not define the granualarity at which memory operations > are done right ? i.e, allocations/deallocations or reclaim cannot be > directed to a section or a group of sections ? Just because there are no users. If you'll be a 1st user, you can add codes, 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