From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx124.postini.com [74.125.245.124]) by kanga.kvack.org (Postfix) with SMTP id 3B5266B005D for ; Tue, 21 Aug 2012 05:32:47 -0400 (EDT) Message-ID: <503354FF.1070809@parallels.com> Date: Tue, 21 Aug 2012 13:29:35 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH V8 1/2] mm: memcg softlimit reclaim rework References: <1343942658-13307-1-git-send-email-yinghan@google.com> <20120803152234.GE8434@dhcp22.suse.cz> <501BF952.7070202@redhat.com> <20120806133324.GD6150@dhcp22.suse.cz> <5031EF4C.6070204@parallels.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Ying Han Cc: Michal Hocko , Rik van Riel , Johannes Weiner , Mel Gorman , KAMEZAWA Hiroyuki , Hillf Danton , Hugh Dickins , KOSAKI Motohiro , Andrew Morton , linux-mm@kvack.org On 08/20/2012 10:30 PM, Ying Han wrote: > Not exactly. Here reclaiming from root is mainly for "reclaiming from > root's exclusive lru", which links the page includes: > 1. processes running under root > 2. reparented pages from rmdir memcg under root > 3. bypassed pages > > Setting root cgroup's softlimit = 0 has the implication of putting > those pages to likely to reclaim, which works fine. The question is > that if no other memcg is above its softlimit, would it be a problem > to adding a bit extra pressure to root which always is eligible for > softlimit reclaim ( usage is always greater than softlimit). > > As an example, it works fine in our environment since we don't > explicitly put any process under root. Most of the pages linked in > root lru would be reparented pages which should be reclaimed prior to > others. Keep in mind that not all environments will be specialized to the point of having root memcg empty. This basically treats root memcg as a trash bin, and can be very detrimental to use cases where actual memory is present in there. It would maybe be better to have all this garbage to go to a separate place, like a shadow garbage memcg, which is invisible to the filesystem, and is always the first to be reclaimed from, in any circumstance. -- 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