From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx199.postini.com [74.125.245.199]) by kanga.kvack.org (Postfix) with SMTP id D16C16B0044 for ; Mon, 6 Aug 2012 09:30:18 -0400 (EDT) Date: Mon, 6 Aug 2012 15:30:15 +0200 From: Michal Hocko Subject: Re: [PATCH V8 2/2] mm: memcg detect no memcgs above softlimit under zone reclaim Message-ID: <20120806133015.GC6150@dhcp22.suse.cz> References: <1343942664-13365-1-git-send-email-yinghan@google.com> <20120803140224.GC8434@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Ying Han Cc: Johannes Weiner , Mel Gorman , KAMEZAWA Hiroyuki , Rik van Riel , Hillf Danton , Hugh Dickins , KOSAKI Motohiro , Andrew Morton , linux-mm@kvack.org On Fri 03-08-12 09:28:22, Ying Han wrote: > On Fri, Aug 3, 2012 at 7:02 AM, Michal Hocko wrote: > > On Thu 02-08-12 14:24:24, Ying Han wrote: [...] > >> diff --git a/mm/vmscan.c b/mm/vmscan.c > >> index 88487b3..8622022 100644 > >> --- a/mm/vmscan.c > >> +++ b/mm/vmscan.c [...] > >> @@ -1879,10 +1883,15 @@ static void shrink_zone(struct zone *zone, struct scan_control *sc) > >> * we have to reclaim under softlimit instead of burning more > >> * cpu cycles. > >> */ > >> - if (!global_reclaim(sc) || sc->priority < DEF_PRIORITY || > >> - mem_cgroup_over_soft_limit(memcg)) > >> + if (ignore_softlimit || !global_reclaim(sc) || > >> + sc->priority < DEF_PRIORITY || > >> + mem_cgroup_over_soft_limit(memcg)) { > >> shrink_lruvec(lruvec, sc); > >> > >> + if (!mem_cgroup_is_root(memcg)) > >> + over_softlimit = true; > >> + } > >> + > > > > I think this is still not sufficient because you do not want to hammer > > root in the ignore_softlimit case. > > Are you worried about over-reclaiming from root cgroup while the rest > of the cgroup are under softimit? yes > Hmm.. That only affect the DEF_PRIORITY level, and not sure how bad it > is. Even if it was for DEF_PRIORITY it would mean that the root group is second class citizen which is definitely not good. > On the other hand, I wonder if it is necessary bad since the pages > under root cgroup are mainly re-parented pages which only get chance > to be reclaimed under global pressure. Hmm, I do not think this is true in general and you shouldn't rely on it. > > --Ying > > > -- > > Michal Hocko > > SUSE Labs -- Michal Hocko SUSE Labs -- 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