From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 774806B025F for ; Fri, 6 Oct 2017 08:05:08 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id y8so9396013wrd.0 for ; Fri, 06 Oct 2017 05:05:08 -0700 (PDT) Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com. [67.231.153.30]) by mx.google.com with ESMTPS id n7si1750607edn.262.2017.10.06.05.05.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 06 Oct 2017 05:05:06 -0700 (PDT) Date: Fri, 6 Oct 2017 13:04:35 +0100 From: Roman Gushchin Subject: Re: [v11 4/6] mm, oom: introduce memory.oom_group Message-ID: <20171006120435.GA22702@castle.dhcp.TheFacebook.com> References: <20171005130454.5590-1-guro@fb.com> <20171005130454.5590-5-guro@fb.com> <20171005143104.wo5xstpe7mhkdlbr@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20171005143104.wo5xstpe7mhkdlbr@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, Vladimir Davydov , Johannes Weiner , Tetsuo Handa , David Rientjes , Andrew Morton , Tejun Heo , kernel-team@fb.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org On Thu, Oct 05, 2017 at 04:31:04PM +0200, Michal Hocko wrote: > Btw. here is how I would do the recursive oom badness. The diff is not > the nicest one because there is some code moving but the resulting code > is smaller and imho easier to grasp. Only compile tested though Thanks! I'm not against this approach, and maybe it can lead to a better code, but the version you sent is just not there yet. There are some problems with it: 1) If there are nested cgroups with oom_group set, you will calculate a badness multiple times, and rely on the fact, that top memcg will become the largest score. It can be optimized, of course, but it's additional code. 2) cgroup_has_tasks() probably requires additional locking. Maybe it's ok to read nr_populated_csets without explicit locking, but it's not obvious for me. 3) Returning -1 from memcg_oom_badness() if eligible is equal to 0 is suspicious. Right now your version has exactly the same amount of code (skipping comments). I assume, this approach just requires some additional thinking/rework. Anyway, thank you for sharing this! > --- > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index 085056e562b1..9cdba4682198 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -122,6 +122,11 @@ void cgroup_free(struct task_struct *p); > int cgroup_init_early(void); > int cgroup_init(void); > > +static bool cgroup_has_tasks(struct cgroup *cgrp) > +{ > + return cgrp->nr_populated_csets; > +} > + > /* > * Iteration helpers and macros. > */ > diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c > index 8dacf73ad57e..a2dd7e3ffe23 100644 > --- a/kernel/cgroup/cgroup.c > +++ b/kernel/cgroup/cgroup.c > @@ -319,11 +319,6 @@ static void cgroup_idr_remove(struct idr *idr, int id) > spin_unlock_bh(&cgroup_idr_lock); > } > > -static bool cgroup_has_tasks(struct cgroup *cgrp) > -{ > - return cgrp->nr_populated_csets; > -} > - > bool cgroup_is_threaded(struct cgroup *cgrp) > { > return cgrp->dom_cgrp != cgrp; -- 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