From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753422Ab0JMIg4 (ORCPT ); Wed, 13 Oct 2010 04:36:56 -0400 Received: from one.firstfloor.org ([213.235.205.2]:50252 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753309Ab0JMIgz (ORCPT ); Wed, 13 Oct 2010 04:36:55 -0400 From: Andi Kleen To: KAMEZAWA Hiroyuki Cc: "linux-mm\@kvack.org" , "linux-kernel\@vger.kernel.org" , "minchan.kim\@gmail.com" , fujita.tomonori@lab.ntt.co.jp Subject: Re: [RFC][PATCH 1/3] contigous big page allocator References: <20101013121527.8ec6a769.kamezawa.hiroyu@jp.fujitsu.com> <87sk0a1sq0.fsf@basil.nowhere.org> <20101013161206.c29df8ea.kamezawa.hiroyu@jp.fujitsu.com> Date: Wed, 13 Oct 2010 10:36:53 +0200 In-Reply-To: <20101013161206.c29df8ea.kamezawa.hiroyu@jp.fujitsu.com> (KAMEZAWA Hiroyuki's message of "Wed, 13 Oct 2010 16:12:06 +0900") Message-ID: <87ocay1obe.fsf@basil.nowhere.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KAMEZAWA Hiroyuki writes: >> > My intention is not for allocating HUGEPAGE(> MAX_ORDER). >> >> I still believe using this for 1GB pages would be one of the more >> interesting use cases. >> > > I'm successfully allocating 1GB of continous pages at test. But I'm not sure > requirements and users. How quick this allocation should be ? This will always be slow. Huge pages are always pre allocated even today through a sysctl. The use case would be have echo XXX > /proc/sys/vm/nr_hugepages at runtime working for 1GB too, instead of requiring a reboot for this. I think it's ok if that is somewhat slow, as long as it is not incredible slow. Ideally it shouldn't cause a swap storm either (maybe we need some way to indicate how hard the freeing code should try?) I guess it would only really work well if you predefine movable zones at boot time. -Andi -- ak@linux.intel.com -- Speaking for myself only.