From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752223AbaEBJgd (ORCPT ); Fri, 2 May 2014 05:36:33 -0400 Received: from cantor2.suse.de ([195.135.220.15]:48545 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752188AbaEBJga (ORCPT ); Fri, 2 May 2014 05:36:30 -0400 Date: Fri, 2 May 2014 11:36:28 +0200 From: Michal Hocko To: Johannes Weiner Cc: Andrew Morton , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Greg Thelen , Michel Lespinasse , Tejun Heo , Hugh Dickins , Roman Gushchin , LKML , linux-mm@kvack.org Subject: Re: [PATCH 1/4] memcg, mm: introduce lowlimit reclaim Message-ID: <20140502093628.GC3446@dhcp22.suse.cz> References: <1398688005-26207-1-git-send-email-mhocko@suse.cz> <1398688005-26207-2-git-send-email-mhocko@suse.cz> <20140430225550.GD26041@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140430225550.GD26041@cmpxchg.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 30-04-14 18:55:50, Johannes Weiner wrote: > On Mon, Apr 28, 2014 at 02:26:42PM +0200, Michal Hocko wrote: > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 19d620b3d69c..40e517630138 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -2808,6 +2808,29 @@ static struct mem_cgroup *mem_cgroup_lookup(unsigned short id) > > return mem_cgroup_from_id(id); > > } > > > > +/** > > + * mem_cgroup_reclaim_eligible - checks whether given memcg is eligible for the > > + * reclaim > > + * @memcg: target memcg for the reclaim > > + * @root: root of the reclaim hierarchy (null for the global reclaim) > > + * > > + * The given group is reclaimable if it is above its low limit and the same > > + * applies for all parents up the hierarchy until root (including). > > + */ > > +bool mem_cgroup_reclaim_eligible(struct mem_cgroup *memcg, > > + struct mem_cgroup *root) > > Could you please rename this to something that is more descriptive in > the reclaim callsite? How about mem_cgroup_within_low_limit()? I have intentionally used somethig that is not low_limit specific. The generic reclaim code does't have to care about the reason why a memcg is not reclaimable. I agree that having follow_low_limit paramter explicit and mem_cgroup_reclaim_eligible not is messy. So something should be renamed. I would probably go with s@follow_low_limit@check_reclaim_eligible@ but I do not have a strong preference. > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index c1cd99a5074b..0f428158254e 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c [...] > > +static void shrink_zone(struct zone *zone, struct scan_control *sc) > > +{ > > + if (!__shrink_zone(zone, sc, true)) { > > + /* > > + * First round of reclaim didn't find anything to reclaim > > + * because of low limit protection so try again and ignore > > + * the low limit this time. > > + */ > > + __shrink_zone(zone, sc, false); > > + } > > } > > > > /* Returns true if compaction should go ahead for a high-order request */ > > I would actually prefer not having a second round here, and make the > low limit behave more like mlock memory. If there is no reclaimable > memory, go OOM. This was done in my previous attempt and I prefer OOM myself but it is also true that starting with a more relaxed limit and adding an option for hard guarantee later when we have a clear usecase is a better approach. Although I can see potential in go-oom-rather-than-reclaim configurations, usecases I am primarily interested in won't overcommit on low_limit. That being said, I like the idea of having the hard guarantee but I also think it should be configurable. I can post those patches in this thread but I feel it is too early as nobody has explicitly asked for this yet. -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f53.google.com (mail-ee0-f53.google.com [74.125.83.53]) by kanga.kvack.org (Postfix) with ESMTP id A65A36B0036 for ; Fri, 2 May 2014 05:36:31 -0400 (EDT) Received: by mail-ee0-f53.google.com with SMTP id b15so1819654eek.12 for ; Fri, 02 May 2014 02:36:31 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id v41si1111835eew.74.2014.05.02.02.36.29 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 02 May 2014 02:36:30 -0700 (PDT) Date: Fri, 2 May 2014 11:36:28 +0200 From: Michal Hocko Subject: Re: [PATCH 1/4] memcg, mm: introduce lowlimit reclaim Message-ID: <20140502093628.GC3446@dhcp22.suse.cz> References: <1398688005-26207-1-git-send-email-mhocko@suse.cz> <1398688005-26207-2-git-send-email-mhocko@suse.cz> <20140430225550.GD26041@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140430225550.GD26041@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Greg Thelen , Michel Lespinasse , Tejun Heo , Hugh Dickins , Roman Gushchin , LKML , linux-mm@kvack.org On Wed 30-04-14 18:55:50, Johannes Weiner wrote: > On Mon, Apr 28, 2014 at 02:26:42PM +0200, Michal Hocko wrote: > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 19d620b3d69c..40e517630138 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -2808,6 +2808,29 @@ static struct mem_cgroup *mem_cgroup_lookup(unsigned short id) > > return mem_cgroup_from_id(id); > > } > > > > +/** > > + * mem_cgroup_reclaim_eligible - checks whether given memcg is eligible for the > > + * reclaim > > + * @memcg: target memcg for the reclaim > > + * @root: root of the reclaim hierarchy (null for the global reclaim) > > + * > > + * The given group is reclaimable if it is above its low limit and the same > > + * applies for all parents up the hierarchy until root (including). > > + */ > > +bool mem_cgroup_reclaim_eligible(struct mem_cgroup *memcg, > > + struct mem_cgroup *root) > > Could you please rename this to something that is more descriptive in > the reclaim callsite? How about mem_cgroup_within_low_limit()? I have intentionally used somethig that is not low_limit specific. The generic reclaim code does't have to care about the reason why a memcg is not reclaimable. I agree that having follow_low_limit paramter explicit and mem_cgroup_reclaim_eligible not is messy. So something should be renamed. I would probably go with s@follow_low_limit@check_reclaim_eligible@ but I do not have a strong preference. > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index c1cd99a5074b..0f428158254e 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c [...] > > +static void shrink_zone(struct zone *zone, struct scan_control *sc) > > +{ > > + if (!__shrink_zone(zone, sc, true)) { > > + /* > > + * First round of reclaim didn't find anything to reclaim > > + * because of low limit protection so try again and ignore > > + * the low limit this time. > > + */ > > + __shrink_zone(zone, sc, false); > > + } > > } > > > > /* Returns true if compaction should go ahead for a high-order request */ > > I would actually prefer not having a second round here, and make the > low limit behave more like mlock memory. If there is no reclaimable > memory, go OOM. This was done in my previous attempt and I prefer OOM myself but it is also true that starting with a more relaxed limit and adding an option for hard guarantee later when we have a clear usecase is a better approach. Although I can see potential in go-oom-rather-than-reclaim configurations, usecases I am primarily interested in won't overcommit on low_limit. That being said, I like the idea of having the hard guarantee but I also think it should be configurable. I can post those patches in this thread but I feel it is too early as nobody has explicitly asked for this yet. -- 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