From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754046AbYCMHNo (ORCPT ); Thu, 13 Mar 2008 03:13:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751621AbYCMHNO (ORCPT ); Thu, 13 Mar 2008 03:13:14 -0400 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:39457 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751141AbYCMHM5 (ORCPT ); Thu, 13 Mar 2008 03:12:57 -0400 Date: Thu, 13 Mar 2008 02:12:53 -0500 From: Paul Jackson To: Max Krasnyanskiy Cc: menage@google.com, mingo@elte.hu, a.p.zijlstra@chello.nl, linux-kernel@vger.kernel.org Subject: Re: boot cgroup questions Message-Id: <20080313021253.a99fc8d1.pj@sgi.com> In-Reply-To: <47D87BE5.4010702@qualcomm.com> References: <47D73086.2030008@qualcomm.com> <6599ad830803111827n1cb8e2c7i47c2ef3f3bb58995@mail.gmail.com> <47D7411E.1000009@qualcomm.com> <6599ad830803111936jd940deam8584bc971c3b6f41@mail.gmail.com> <47D74595.4080100@qualcomm.com> <6599ad830803112009y18d9e43ft8e3fc4a551d891da@mail.gmail.com> <20080311235939.1ebee8e3.pj@sgi.com> <47D81FE1.6030205@qualcomm.com> <20080312135746.89456f2a.pj@sgi.com> <47D82AD2.1070108@qualcomm.com> <20080312143253.3dd72c7f.pj@sgi.com> <47D83858.4030806@qualcomm.com> <20080312153712.bc5df7a1.pj@sgi.com> <47D8593A.6040503@qualcomm.com> <20080312183059.6716d630.pj@sgi.com> <47D87BE5.4010702@qualcomm.com> Organization: SGI X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.12.0; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > How about we add support for sym links to the cgroup fs ? Still pollutes the primary cpuset name space ... you have all the directories X, X/A, and X/B as well as the symlinks A and B. Symlinks allow for one path that needs to be 'aliased' to another, but they are a one-way map; without an exhaustive search of the potential namespace, one can't invert them, or determine if they can't be inverted. Tools have to constantly make heuristic decisions whether to default to dereferencing the symlink, or not, and often have to provide alternatives for the non-default choice. They are a pain in the backside even if designed in and expected up front. If added as critical structure after the fact, something breaks, pretty much for sure. For one minor example, code I've probably buried someplace that does "find /dev/cpuset -type d" to find all cpusets would break. Or the one-line /sbin/cpuset_release_agent script: rmdir /dev/cpuset/$1 is broken -- fails to clean-up associated symlinks, and can't avoid race conditions if it tries to add code to do that. > Crazy idea. Agreed ;) But nice picture ;). -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.940.382.4214