From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFD] cgroup: about multiple hierarchies Date: Mon, 12 Mar 2012 15:39:44 -0700 Message-ID: <20120312223944.GJ23255@google.com> References: <20120221211938.GE12236@google.com> <20120312221050.GG23255@google.com> <1331590938.18960.57.camel@twins> <20120312222817.GI23255@google.com> <1331591568.18960.61.camel@twins> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=jyR4+VlryNe6sfJBz42lt0yLF4ljvRgwZ+qQsBPDeE8=; b=M1eHYsu+xCsLjjEL2OkYIQBSWVs0FYf21AURin0iM2okH1v3fwTO09FRMcMQkTm5IT Zbg9b5ibah8f1Bln6KLAxNQlvKPDXCkaC1QLW6rnweN7wWpvrYXuuRHUbLomynhBWhpj hZ4pcJosg9PXiG/Mhc9BsA3i9piekuSPcn3xi9DHrg54zRc4M9AKhXj7Q/WdySlzs45+ aq64pn/AsbixjqDxxvlTBQkF7GQIXB/pFcuHWNZWQIPsZmbQ8a0Vgr08lNvqBvQBZCIV QqQlC7MLB/G0DQ7/EbIQMxVnIeZ1sLWERKaYf+6gl3ZkU7JoYn5vqqa8k8QE8WIxWgIg mFYA== Content-Disposition: inline In-Reply-To: <1331591568.18960.61.camel@twins> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Zijlstra Cc: Li Zefan , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrew Morton , Kay Sievers , Lennart Poettering , Frederic Weisbecker , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vivek Goyal , Michal Schmidt Hello, On Mon, Mar 12, 2012 at 11:32:48PM +0100, Peter Zijlstra wrote: > I'm assuming that G31/G32's tasks end up in G3 in the first case, but > where do the tasks in G3 go to in the second case? Collapsed into the root group. The controller simply doesn't have anything configured at that layer. > Also, why allow non-hierarchical controllers to begin with? I would very > much argue for mandating that all controllers work the same wrt > hierarchy and if that means ditching hierarchy support we should do that > and modify cgroupfs to not allow creation of directories deeper than 1. > > But allowing controllers that implement hierarchy proper and controllers > that do not and then force them in the same mount point, that just > doesn't make any friggin sense what so ever. Hmmm... that could be a good final goal but I think supporting mapping to flat structure will simplify the transition much easier, or possible. That way, core transition can be mostly decoupled from controller updates. If we can get to the point where nesting is fully supported by every controller first, that would be awesome too. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757824Ab2CLWjv (ORCPT ); Mon, 12 Mar 2012 18:39:51 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:62289 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753418Ab2CLWjt (ORCPT ); Mon, 12 Mar 2012 18:39:49 -0400 Date: Mon, 12 Mar 2012 15:39:44 -0700 From: Tejun Heo To: Peter Zijlstra Cc: Li Zefan , containers@lists.linux-foundation.org, cgroups@vger.kernel.org, Andrew Morton , Kay Sievers , Lennart Poettering , Frederic Weisbecker , linux-kernel@vger.kernel.org, Vivek Goyal , Michal Schmidt Subject: Re: [RFD] cgroup: about multiple hierarchies Message-ID: <20120312223944.GJ23255@google.com> References: <20120221211938.GE12236@google.com> <20120312221050.GG23255@google.com> <1331590938.18960.57.camel@twins> <20120312222817.GI23255@google.com> <1331591568.18960.61.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1331591568.18960.61.camel@twins> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Mon, Mar 12, 2012 at 11:32:48PM +0100, Peter Zijlstra wrote: > I'm assuming that G31/G32's tasks end up in G3 in the first case, but > where do the tasks in G3 go to in the second case? Collapsed into the root group. The controller simply doesn't have anything configured at that layer. > Also, why allow non-hierarchical controllers to begin with? I would very > much argue for mandating that all controllers work the same wrt > hierarchy and if that means ditching hierarchy support we should do that > and modify cgroupfs to not allow creation of directories deeper than 1. > > But allowing controllers that implement hierarchy proper and controllers > that do not and then force them in the same mount point, that just > doesn't make any friggin sense what so ever. Hmmm... that could be a good final goal but I think supporting mapping to flat structure will simplify the transition much easier, or possible. That way, core transition can be mostly decoupled from controller updates. If we can get to the point where nesting is fully supported by every controller first, that would be awesome too. Thanks. -- tejun