From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 397FD6B004A for ; Fri, 22 Jul 2011 05:35:38 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 0CC043EE0AE for ; Fri, 22 Jul 2011 18:35:35 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id E809D45DE61 for ; Fri, 22 Jul 2011 18:35:34 +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 C525F45DE7E for ; Fri, 22 Jul 2011 18:35:34 +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 B507A1DB802C for ; Fri, 22 Jul 2011 18:35:34 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.240.81.133]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 7F3FB1DB8038 for ; Fri, 22 Jul 2011 18:35:34 +0900 (JST) Date: Fri, 22 Jul 2011 18:28:22 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 1/4] memcg: do not try to drain per-cpu caches without pages Message-Id: <20110722182822.a99a2676.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110722091936.GB4004@tiehlicka.suse.cz> References: <113c4affc2f0938b7b22d43c88d2b0a623de9a6b.1311241300.git.mhocko@suse.cz> <20110721191250.1c945740.kamezawa.hiroyu@jp.fujitsu.com> <20110721113606.GA27855@tiehlicka.suse.cz> <20110722084413.9dd4b880.kamezawa.hiroyu@jp.fujitsu.com> <20110722091936.GB4004@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: linux-mm@kvack.org, Balbir Singh , Daisuke Nishimura , linux-kernel@vger.kernel.org On Fri, 22 Jul 2011 11:19:36 +0200 Michal Hocko wrote: > On Fri 22-07-11 08:44:13, KAMEZAWA Hiroyuki wrote: > > On Thu, 21 Jul 2011 13:36:06 +0200 > > Michal Hocko wrote: > > > > > On Thu 21-07-11 19:12:50, KAMEZAWA Hiroyuki wrote: > > > > On Thu, 21 Jul 2011 09:38:00 +0200 > > > > Michal Hocko wrote: > > > > > > > > > drain_all_stock_async tries to optimize a work to be done on the work > > > > > queue by excluding any work for the current CPU because it assumes that > > > > > the context we are called from already tried to charge from that cache > > > > > and it's failed so it must be empty already. > > > > > While the assumption is correct we can do it by checking the current > > > > > number of pages in the cache. This will also reduce a work on other CPUs > > > > > with an empty stock. > > > > > > > > > > Signed-off-by: Michal Hocko > > > > > > > > > > > > At the first look, when a charge against TransParentHugepage() goes > > > > into the reclaim routine, stock->nr_pages != 0 and this will > > > > call additional kworker. > > > > > > True. We will drain a charge which could be used by other allocations > > > in the meantime so we have a good chance to reclaim less. But how big > > > problem is that? > > > I mean I can add a new parameter that would force checking the current > > > cpu but it doesn't look nice. I cannot add that condition > > > unconditionally because the code will be shared with the sync path in > > > the next patch and that one needs to drain _all_ cpus. > > > > > > What would you suggest? > > By 2 methods > > > > - just check nr_pages. > > Not sure I understand which nr_pages you mean. The one that comes from > the charging path or stock->nr_pages? > If you mean the first one then we do not have in the reclaim path where > we call drain_all_stock_async. > stock->nr_pages. > > - drain "local stock" without calling schedule_work(). It's fast. > > but there is nothing to be drained locally in the paths where we call > drain_all_stock_async... Or do you mean that drain_all_stock shouldn't > use work queue at all? I mean calling schedule_work against local cpu is just waste of time. Then, drain it directly and move local cpu's stock->nr_pages to res_counter. 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