From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 2 Mar 2007 14:50:29 +0900 From: KAMEZAWA Hiroyuki Subject: Re: The performance and behaviour of the anti-fragmentation related patches Message-Id: <20070302145029.d4847577.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <20070301101249.GA29351@skynet.ie> <20070301160915.6da876c5.akpm@linux-foundation.org> <45E7835A.8000908@in.ibm.com> <20070301195943.8ceb221a.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: akpm@linux-foundation.org, balbir@in.ibm.com, mel@skynet.ie, npiggin@suse.de, clameter@engr.sgi.com, mingo@elte.hu, jschopp@austin.ibm.com, arjan@infradead.org, mbligh@mbligh.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Thu, 1 Mar 2007 21:11:58 -0800 (PST) Linus Torvalds wrote: > The whole DRAM power story is a bedtime story for gullible children. Don't > fall for it. It's not realistic. The hardware support for it DOES NOT > EXIST today, and probably won't for several years. And the real fix is > elsewhere anyway (ie people will have to do a FBDIMM-2 interface, which > is against the whole point of FBDIMM in the first place, but that's what > you get when you ignore power in the first version!). > At first, we have memory hot-add now. So I want to implement hot-removing hot-added memory, at least. (in this case, we don't have to write invasive patches to memory-init-core.) Our(Fujtisu's) product, ia64-NUMA server, has a feature to offline memory. It supports dynamic reconfigraion of nodes, node-hoplug. But there is no *shipped* firmware for hotplug yet. RHEL4 couldn't boot on such hotplug-supported-firmware...so firmware-team were not in hurry. It will be shipped after RHEL5 comes. IMHO, a firmware which supports memory-hot-add are ready to support memory-hot-remove if OS can handle it. Note: I heard embeded people often designs their own memory-power-off control on embeded Linux. (but it never seems to be posted to the list.) But I don't know they are interested in generic memory hotremove or not. 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/ . Don't email: email@kvack.org