From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balbir Singh Subject: Re: [-mm] Add an owner to the mm_struct (v8) Date: Tue, 08 Apr 2008 08:09:57 +0530 Message-ID: <47FADAFD.7030202@linux.vnet.ibm.com> References: <20080404080544.26313.38199.sendpatchset@localhost.localdomain> <20080407150956.9a29573a.akpm@linux-foundation.org> Reply-To: balbir@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080407150956.9a29573a.akpm@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: menage@google.com, xemul@openvz.org, hugh@veritas.com, skumar@linux.vnet.ibm.com, yamamoto@valinux.co.jp, lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, taka@valinux.co.jp, linux-mm@kvack.org, rientjes@google.com, kamezawa.hiroyu@jp.fujitsu.com List-Id: linux-mm.kvack.org Andrew Morton wrote: > On Fri, 04 Apr 2008 13:35:44 +0530 > Balbir Singh wrote: > >> 1. Add mm->owner change callbacks using cgroups >> >> ... >> >> +config MM_OWNER >> + bool "Enable ownership of mm structure" >> + help >> + This option enables mm_struct's to have an owner. The advantage >> + of this approach is that it allows for several independent memory >> + based cgroup controllers to co-exist independently without too >> + much space overhead >> + >> + This feature adds fork/exit overhead. So enable this only if >> + you need resource controllers > > Do we really want to offer this option to people? It's rather a low-level > thing and it's likely to cause more confusion than it's worth. Remember > that most kernels get to our users via kernel vendors - to what will they > be setting this config option? > I suspect that this kernel option will not be explicitly set it. This option will be selected by other config options (memory controller, swap namespace, revoke*) >> config CGROUP_MEM_RES_CTLR >> bool "Memory Resource Controller for Control Groups" >> depends on CGROUPS && RESOURCE_COUNTERS >> + select MM_OWNER > > Presumably they'll always be setting it to "y" if they are enabling cgroups > at all. > >> --- linux-2.6.25-rc8/kernel/cgroup.c~memory-controller-add-mm-owner 2008-04-03 22:43:27.000000000 +0530 >> +++ linux-2.6.25-rc8-balbir/kernel/cgroup.c 2008-04-03 22:43:27.000000000 +0530 >> @@ -118,6 +118,7 @@ static int root_count; >> * be called. >> */ >> static int need_forkexit_callback; >> +static int need_mm_owner_callback; > > I suppose these should be __read_mostly. > Yes, good point. I'll send out v9 with this fix. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL