Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754029AbbETQoY (ORCPT ); Wed, 20 May 2015 12:44:24 -0400 Received: from cantor2.suse.de ([195.135.220.15]:34913 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753158AbbETQoX (ORCPT ); Wed, 20 May 2015 12:44:23 -0400 Date: Wed, 20 May 2015 17:44:19 +0100 From: Mel Gorman To: Johannes Weiner Cc: Michal Hocko , Andrew Morton , Tejun Heo , Linux-CGroups , Linux-MM , LKML 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> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1428 Lines: 33 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 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/