From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx202.postini.com [74.125.245.202]) by kanga.kvack.org (Postfix) with SMTP id 7BB566B002B for ; Mon, 15 Oct 2012 20:51:21 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 3FC193EE0C7 for ; Tue, 16 Oct 2012 09:51:19 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id D5B0545DEBC for ; Tue, 16 Oct 2012 09:51:18 +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 BBE8B45DEBB for ; Tue, 16 Oct 2012 09:51:18 +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 AA28C1DB8040 for ; Tue, 16 Oct 2012 09:51:18 +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 5BF5E1DB803F for ; Tue, 16 Oct 2012 09:51:18 +0900 (JST) Message-ID: <507CAF77.1020409@jp.fujitsu.com> Date: Tue, 16 Oct 2012 09:51:03 +0900 From: Kamezawa Hiroyuki MIME-Version: 1.0 Subject: Re: [PATCH] doc: describe memcg swappiness more precisely memory.swappiness==0 References: <20121011085038.GA29295@dhcp22.suse.cz> <1349945859-1350-1-git-send-email-mhocko@suse.cz> <20121015220354.GA11682@dhcp22.suse.cz> <20121015220725.GB11682@dhcp22.suse.cz> In-Reply-To: <20121015220725.GB11682@dhcp22.suse.cz> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , linux-mm@kvack.org, David Rientjes , KOSAKI Motohiro , Johannes Weiner , LKML (2012/10/16 7:07), Michal Hocko wrote: > And a follow up for memcg.swappiness documentation which is more > specific about spwappiness==0 meaning. > --- > From 1bc3a94fea728107ed108edd42df464b908cd067 Mon Sep 17 00:00:00 2001 > From: Michal Hocko > Date: Mon, 15 Oct 2012 11:43:56 +0200 > Subject: [PATCH] doc: describe memcg swappiness more precisely > > since fe35004f (mm: avoid swapping out with swappiness==0) memcg reclaim > stopped swapping out anon pages completely when 0 value is used. > Although this is somehow expected it hasn't been done for a really long > time this way and so it is probably better to be explicit about the > effect. Moreover global reclaim swapps out even when swappiness is 0 > to prevent from OOM killer. > > Signed-off-by: Michal Hocko Nice :) Acked-by: KAMEZAWA Hiroyuki > --- > Documentation/cgroups/memory.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt > index c07f7b4..71c4da4 100644 > --- a/Documentation/cgroups/memory.txt > +++ b/Documentation/cgroups/memory.txt > @@ -466,6 +466,10 @@ Note: > 5.3 swappiness > > Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only. > +Please note that unlike the global swappiness, memcg knob set to 0 > +really prevents from any swapping even if there is a swap storage > +available. This might lead to memcg OOM killer if there are no file > +pages to reclaim. > > Following cgroups' swappiness can't be changed. > - root cgroup (uses /proc/sys/vm/swappiness). > -- 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