From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f52.google.com (mail-ee0-f52.google.com [74.125.83.52]) by kanga.kvack.org (Postfix) with ESMTP id E7A9A6B0035 for ; Tue, 22 Apr 2014 05:25:14 -0400 (EDT) Received: by mail-ee0-f52.google.com with SMTP id e49so4382318eek.11 for ; Tue, 22 Apr 2014 02:25:14 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u5si58891860een.143.2014.04.22.02.25.12 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 22 Apr 2014 02:25:13 -0700 (PDT) Date: Tue, 22 Apr 2014 11:25:08 +0200 From: Michal Hocko Subject: Re: [PATCH] Documentation/memcg: warn about incomplete kmemcg state Message-ID: <20140422092508.GA29311@dhcp22.suse.cz> References: <1398066420-30707-1-git-send-email-vdavydov@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1398066420-30707-1-git-send-email-vdavydov@parallels.com> Sender: owner-linux-mm@kvack.org List-ID: To: Vladimir Davydov Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Mon 21-04-14 11:47:00, Vladimir Davydov wrote: > Kmemcg is currently under development and lacks some important features. > In particular, it does not have support of kmem reclaim on memory > pressure inside cgroup, which practically makes it unusable in real > life. Let's warn about it in both Kconfig and Documentation to prevent > complaints arising. > > Signed-off-by: Vladimir Davydov Thanks! This should have been merged log time ago... Acked-by: Michal Hocko > --- > Documentation/cgroups/memory.txt | 5 +++++ > init/Kconfig | 6 ++++++ > 2 files changed, 11 insertions(+) > > diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt > index 2622115276aa..af3cdfa3c07a 100644 > --- a/Documentation/cgroups/memory.txt > +++ b/Documentation/cgroups/memory.txt > @@ -270,6 +270,11 @@ When oom event notifier is registered, event will be delivered. > > 2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM) > > +WARNING: Current implementation lacks reclaim support. That means allocation > + attempts will fail when close to the limit even if there are plenty of > + kmem available for reclaim. That makes this option unusable in real > + life so DO NOT SELECT IT unless for development purposes. > + > With the Kernel memory extension, the Memory Controller is able to limit > the amount of kernel memory used by the system. Kernel memory is fundamentally > different than user memory, since it can't be swapped out, which makes it > diff --git a/init/Kconfig b/init/Kconfig > index 427ba60d638f..4d6e645c8ad4 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -993,6 +993,12 @@ config MEMCG_KMEM > the kmem extension can use it to guarantee that no group of processes > will ever exhaust kernel resources alone. > > + WARNING: Current implementation lacks reclaim support. That means > + allocation attempts will fail when close to the limit even if there > + are plenty of kmem available for reclaim. That makes this option > + unusable in real life so DO NOT SELECT IT unless for development > + purposes. > + > config CGROUP_HUGETLB > bool "HugeTLB Resource Controller for Control Groups" > depends on RESOURCE_COUNTERS && HUGETLB_PAGE > -- > 1.7.10.4 > -- 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