From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 56AAA6B0253 for ; Thu, 5 Oct 2017 07:46:25 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id g10so10883616wrg.2 for ; Thu, 05 Oct 2017 04:46:25 -0700 (PDT) Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com. [67.231.153.30]) by mx.google.com with ESMTPS id i34si3667494edi.396.2017.10.05.04.46.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 Oct 2017 04:46:24 -0700 (PDT) Date: Thu, 5 Oct 2017 12:45:51 +0100 From: Roman Gushchin Subject: Re: [v10 3/6] mm, oom: cgroup-aware OOM killer Message-ID: <20171005114551.GA6338@castle.dhcp.TheFacebook.com> References: <20171004154638.710-1-guro@fb.com> <20171004154638.710-4-guro@fb.com> <20171004201524.GA4174@castle> <20171005102707.GA12982@castle.dhcp.TheFacebook.com> <20171005111230.i7am3patptvalcat@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20171005111230.i7am3patptvalcat@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Shakeel Butt , Linux MM , Vladimir Davydov , Johannes Weiner , Tetsuo Handa , David Rientjes , Andrew Morton , Tejun Heo , kernel-team@fb.com, Cgroups , linux-doc@vger.kernel.org, LKML On Thu, Oct 05, 2017 at 01:12:30PM +0200, Michal Hocko wrote: > On Thu 05-10-17 11:27:07, Roman Gushchin wrote: > > On Wed, Oct 04, 2017 at 02:24:26PM -0700, Shakeel Butt wrote: > [...] > > > Sorry about the confusion. There are two things. First, should we do a > > > css_get on the newly selected memcg within the for loop when we still > > > have a reference to it? > > > > We're holding rcu_read_lock, it should be enough. We're bumping css counter > > just before releasing rcu lock. > > yes > > > > > > > Second, for the OFFLINE memcg, you are right oom_evaluate_memcg() will > > > return 0 for offlined memcgs. Maybe no need to call > > > oom_evaluate_memcg() for offlined memcgs. > > > > Sounds like a good optimization, which can be done on top of the current > > patchset. > > You could achive this by checking whether a memcg has tasks rather than > explicitly checking for children memcgs as I've suggested already. Using cgroup_has_tasks() will require additional locking, so I'm not sure it worth it. -- 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