From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f49.google.com (mail-ee0-f49.google.com [74.125.83.49]) by kanga.kvack.org (Postfix) with ESMTP id 1664F6B0031 for ; Mon, 6 Jan 2014 09:03:06 -0500 (EST) Received: by mail-ee0-f49.google.com with SMTP id c41so7902560eek.36 for ; Mon, 06 Jan 2014 06:03:06 -0800 (PST) Received: from moutng.kundenserver.de (moutng.kundenserver.de. [212.227.17.10]) by mx.google.com with ESMTPS id y48si4553616eew.142.2014.01.06.06.03.06 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 06 Jan 2014 06:03:06 -0800 (PST) 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 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" Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Wanpeng Li , Ingo Molnar , Andrew Morton , linux-mm@kvack.org, 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 -- 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