From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754710AbaAFODj (ORCPT ); Mon, 6 Jan 2014 09:03:39 -0500 Received: from moutng.kundenserver.de ([212.227.17.10]:61379 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750805AbaAFODi (ORCPT ); Mon, 6 Jan 2014 09:03:38 -0500 Message-ID: <1389016976.5536.10.camel@marge.simpson.net> Subject: Re: [PATCH] sched/auto_group: fix consume memory even if add 'noautogroup' in the cmdline From: Mike Galbraith To: Peter Zijlstra Cc: Wanpeng Li , Ingo Molnar , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Mon, 06 Jan 2014 15:02:56 +0100 In-Reply-To: <20140106121719.GH31570@twins.programming.kicks-ass.net> References: <1388139751-19632-1-git-send-email-liwanp@linux.vnet.ibm.com> <20140106121719.GH31570@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 X-Provags-ID: V02:K0:vd0z/8Z1TsJps7mepPNryOdJgdwheyvhwzaP45N52JK sdmLPp5dHTLNGXijmj+qXAd18I1uxt4GqrbAdGjDsevcxchRmb h8BJQrD3dmeZa3IMGoLN+FcL/wu9xeLVOvyj28YlB6ltdKa9EY sxrcfV4H6vG2CG+A2uvqCNd2SbYH/OpQBFC+H4mNZD/dEp+nbQ nMERDkWUtGZUbJEHQPR07euZUBE7SHBmFKWZhYdG983f1s2Owm gIR/ZWnnqwsvj/eQJXVqkVyDbxrVT/PeU5v16jfSsEHAZbYaBp dUuvKySDJlqPXwqcVXxvbmOMu+vyolk8AYQyXzouEBSnw9G4Mt CGQy1RjXAbOY0NjQxpmlJzF3HGt8zVTsGRp4kod/LpPD773bQZ +m51CiMJk0+1A== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2014-01-06 at 13:17 +0100, Peter Zijlstra wrote: > On Fri, Dec 27, 2013 at 06:22:31PM +0800, Wanpeng Li wrote: > > We have a server which have 200 CPUs and 8G memory, there is auto_group creation > > I'm hoping that is 8T, otherwise that's a severely under provisioned > system, that's a mere 40M per cpu, does that even work? > > > which will almost consume 12MB memory even if add 'noautogroup' in the kernel > > boot parameter. In addtion, SLUB per cpu partial caches freeing that is local to > > a processor which requires the taking of locks at the price of more indeterminism > > in the latency of the free. This patch fix it by check noautogroup earlier to avoid > > free after unnecessary memory consumption. > > That's just a bad changelog. It fails to explain the actual problem and > it babbles about unrelated things like SLUB details. > > Also, I'm not entirely sure what the intention was of this code, I've so > far tried to ignore the entire autogroup fest... > > It looks like it creates and maintains the entire autogroup hierarchy, > such that if you at runtime enable the sysclt and move tasks 'back' to > the root cgroup you get the autogroup behaviour. > > Was this intended? Mike? Yeah, it was intended that autogroups always exist if you config it in. We could make is such that noautogroup makes it irreversibly off/dead. People with 200 ram starved CPUs can turn it off in their .config too :) -Mike