From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755143AbZBCTOY (ORCPT ); Tue, 3 Feb 2009 14:14:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752116AbZBCTOM (ORCPT ); Tue, 3 Feb 2009 14:14:12 -0500 Received: from smtp-out.google.com ([216.239.33.17]:28864 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754144AbZBCTOK (ORCPT ); Tue, 3 Feb 2009 14:14:10 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:content-transfer-encoding: x-gmailtapped-by:x-gmailtapped; b=n45pO0Ced+UdtuS29wtoiHlMDxfQPDVzrtPtU5Khm/Q2mRxSnTJJzrMYRZlO/DTxo kF7z5zeMGn3Wm9Erx6WlA== MIME-Version: 1.0 In-Reply-To: <20090203185117.GB3359@mini-me.seanius.net> References: <20090202200013.GU3643@vespa.holoscopio.com> <1233606371.15779.32.camel@radis.liafa.jussieu.fr> <20090202205246.GA28593@glandium.org> <20090202214153.GV3643@vespa.holoscopio.com> <20090203102416.GA8886@redhat.com> <87ljsnzo4v.fsf@benfinney.id.au> <1233671913.8902.53.camel@abacate.horta> <6599ad830902030855h1753f4a4o3a303b4dbddf10de@mail.gmail.com> <20090203184915.GA10004@glandium.org> <20090203185117.GB3359@mini-me.seanius.net> Date: Tue, 3 Feb 2009 11:14:03 -0800 Message-ID: <6599ad830902031114t7de1b570p4ed5ec497e2e150e@mail.gmail.com> Subject: Re: cgroup mount point From: Paul Menage To: sean finney Cc: Gustavo Noronha , debian-devel@lists.debian.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-GMailtapped-By: 172.25.146.38 X-GMailtapped: menage Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 3, 2009 at 10:51 AM, sean finney wrote: > On Tue, Feb 03, 2009 at 07:49:15PM +0100, Mike Hommey wrote: >> > Having one virtual filesystem mounted on top of another virtual >> > filesystem seems like a recipe for problems. >> >> Like with /sys/fs/fuse/connections ? Come on, there is no problem with a >> virtual filesystem mounted on top of another. > > or /proc/bus/usb or /dev/shm or /dev/pts... :) > /dev is a bit different though - even if it's mounted as a udev fs, you can create a new directory in there to act as a mount point. Cgroups supports multiple hierarchies on different mount points. So if you have two cgroups hierarchies - say one for CPU/network and one for memory isolation, you could create /dev/cgroup/cpunet and /dev/cgroup/memory and mount the two hierarchies. But sysfs doesn't allow you to create new subdirectories to act as mountpoints. If we can have a /sys/cgroups directory which allows you to create arbitrary subdirs to act as mountpoints, that could be OK. Or just fake it by mounting a tmpfs on /sys/cgroups and then create mount points in there, but that seems like a bit of a hack. Paul