From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f180.google.com (mail-wi0-f180.google.com [209.85.212.180]) by kanga.kvack.org (Postfix) with ESMTP id 934156B0133 for ; Wed, 20 May 2015 12:44:23 -0400 (EDT) Received: by wibt6 with SMTP id t6so66748140wib.0 for ; Wed, 20 May 2015 09:44:23 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id t1si4742616wif.84.2015.05.20.09.44.21 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 20 May 2015 09:44:22 -0700 (PDT) Date: Wed, 20 May 2015 17:44:19 +0100 From: Mel Gorman Subject: Re: [PATCH 2/2] mm, memcg: Optionally disable memcg by default using Kconfig Message-ID: <20150520164419.GT2462@suse.de> References: <1432126245-10908-1-git-send-email-mgorman@suse.de> <1432126245-10908-3-git-send-email-mgorman@suse.de> <20150520162421.GB2874@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20150520162421.GB2874@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Michal Hocko , Andrew Morton , Tejun Heo , Linux-CGroups , Linux-MM , LKML On Wed, May 20, 2015 at 12:24:21PM -0400, Johannes Weiner wrote: > > > > Low thread counts get a small boost but it's within noise as memcg overhead > > does not dominate. It's not obvious at all at higher thread counts as other > > factors cause more problems. The overall breakdown of CPU usage looks like > > > > 4.0.0 4.0.0 > > chargefirst-v2r1disable-v2r1 > > User 41.81 41.45 > > System 407.64 405.50 > > Elapsed 128.17 127.06 > > This is a worst case microbenchmark doing nothing but anonymous page > faults (with THP disabled), and yet the performance difference is in > the noise. I don't see why we should burden the user with making a > decision that doesn't matter in theory, let alone in practice. > > We have CONFIG_MEMCG and cgroup_disable=memory, that should be plenty > for users that obsess about fluctuation in the noise. There is no > reason to complicate the world further for everybody else. FWIW, I agree and only included this patch because I said I would yesterday. After patch 1, there is almost no motivation to disable memcg at all let alone by default. -- Mel Gorman 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