From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 6738C8D0039 for ; Thu, 24 Feb 2011 05:09:10 -0500 (EST) Received: from m1.gw.fujitsu.co.jp (unknown [10.0.50.71]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 3ABE23EE0BB for ; Thu, 24 Feb 2011 19:09:03 +0900 (JST) Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 24E3945DE5B for ; Thu, 24 Feb 2011 19:09:03 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 0CCF745DE58 for ; Thu, 24 Feb 2011 19:09:03 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id F231EE38005 for ; Thu, 24 Feb 2011 19:09:02 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id BD6D5E38003 for ; Thu, 24 Feb 2011 19:09:02 +0900 (JST) Date: Thu, 24 Feb 2011 19:02:47 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC PATCH] page_cgroup: Reduce allocation overhead for page_cgroup array for CONFIG_SPARSEMEM Message-Id: <20110224190247.bdc2e6f8.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110224093519.GB20922@tiehlicka.suse.cz> References: <20110223151047.GA7275@tiehlicka.suse.cz> <1298485162.7236.4.camel@nimitz> <20110224085227.1a3e185b.kamezawa.hiroyu@jp.fujitsu.com> <20110224093519.GB20922@tiehlicka.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Dave Hansen , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, 24 Feb 2011 10:35:19 +0100 Michal Hocko wrote: > On Thu 24-02-11 08:52:27, KAMEZAWA Hiroyuki wrote: > > On Wed, 23 Feb 2011 10:19:22 -0800 > > Dave Hansen wrote: > > > > > On Wed, 2011-02-23 at 16:10 +0100, Michal Hocko wrote: > > > > We can reduce this internal fragmentation by splitting the single > > > > page_cgroup array into more arrays where each one is well kmalloc > > > > aligned. This patch implements this idea. > > > > > > How about using alloc_pages_exact()? These things aren't allocated > > > often enough to really get most of the benefits of being in a slab. > > > That'll at least get you down to a maximum of about PAGE_SIZE wasted. > > > > > > > yes, alloc_pages_exact() is much better. > > > > packing page_cgroups for multiple sections causes breakage in memory hotplug logic. > > I am not sure I understand this. What do you mean by packing > page_cgroups for multiple sections? The patch I have posted doesn't do > any packing. Or do you mean that using a double array can break hotplog? > Not that this would change anything, alloc_pages_exact is really a > better solution, I am just curious ;) > Sorry, it seems I failed to read code correctly. You just implemented 2 level table.. 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