Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753540AbaKDNlR (ORCPT ); Tue, 4 Nov 2014 08:41:17 -0500 Received: from cantor2.suse.de ([195.135.220.15]:47442 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751104AbaKDNlO (ORCPT ); Tue, 4 Nov 2014 08:41:14 -0500 Date: Tue, 4 Nov 2014 14:41:10 +0100 From: Michal Hocko To: Johannes Weiner Cc: Kamezawa Hiroyuki , Andrew Morton , Vladimir Davydov , Tejun Heo , David Miller , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch 1/3] mm: embed the memcg pointer directly into struct page Message-ID: <20141104134110.GD22207@dhcp22.suse.cz> References: <1414898156-4741-1-git-send-email-hannes@cmpxchg.org> <54589017.9060604@jp.fujitsu.com> <20141104132701.GA18441@phnom.home.cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141104132701.GA18441@phnom.home.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 Tue 04-11-14 08:27:01, Johannes Weiner wrote: > From: Johannes Weiner > Subject: [patch] mm: move page->mem_cgroup bad page handling into generic code fix > > Remove obsolete memory saving recommendations from the MEMCG Kconfig > help text. The memory overhead is still there. So I do not think it is good to remove the message altogether. The current overhead might be 4 or 8B depending on the configuration. What about " Note that setting this option might increase fixed memory overhead associated with each page descriptor in the system. The memory overhead depends on the architecture and other configuration options which have influence on the size and alignment on the page descriptor (struct page). Namely CONFIG_SLUB has a requirement for page alignment to two words which in turn means that 64b systems might not see any memory overhead as the additional data fits into alignment. On the other hand 32b systems might see 8B memory overhead. " > Signed-off-by: Johannes Weiner > --- > init/Kconfig | 12 ------------ > 1 file changed, 12 deletions(-) > > diff --git a/init/Kconfig b/init/Kconfig > index 01b7f2a6abf7..d68d8b0780b3 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -983,18 +983,6 @@ config MEMCG > Provides a memory resource controller that manages both anonymous > memory and page cache. (See Documentation/cgroups/memory.txt) > > - Note that setting this option increases fixed memory overhead > - associated with each page of memory in the system. By this, > - 8(16)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory > - usage tracking struct at boot. Total amount of this is printed out > - at boot. > - > - Only enable when you're ok with these trade offs and really > - sure you need the memory resource controller. Even when you enable > - this, you can set "cgroup_disable=memory" at your boot option to > - disable memory resource controller and you can avoid overheads. > - (and lose benefits of memory resource controller) > - > config MEMCG_SWAP > bool "Memory Resource Controller Swap Extension" > depends on MEMCG && SWAP > -- > 2.1.3 > -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/