From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753622Ab2AWScM (ORCPT ); Mon, 23 Jan 2012 13:32:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37399 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752749Ab2AWScL (ORCPT ); Mon, 23 Jan 2012 13:32:11 -0500 Date: Mon, 23 Jan 2012 13:32:07 -0500 From: Vivek Goyal To: Tejun Heo Cc: axboe@kernel.dk, ctalbott@google.com, rni@google.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/17] blkcg: shoot down blkio_groups on elevator switch Message-ID: <20120123183207.GL25986@redhat.com> References: <1327202725-3383-1-git-send-email-tj@kernel.org> <1327202725-3383-9-git-send-email-tj@kernel.org> <20120123152055.GD25986@redhat.com> <20120123153913.GB12652@google.com> <20120123155216.GF25986@redhat.com> <20120123155745.GD12652@google.com> <20120123161042.GG25986@redhat.com> <20120123161619.GE12652@google.com> <20120123162553.GI25986@redhat.com> <20120123171049.GH12652@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120123171049.GH12652@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 23, 2012 at 09:10:49AM -0800, Tejun Heo wrote: [..] > No matter what we do for #2, #1 requires ordering between policy > selection and configuration. You're saying that #2, combined with the > fact that blk-throtl can't be built as module or disabled on runtime, > allows side-stepping the issue for at least blk-throtl. That doesn't > sound like a good idea to me. People are working on different > elevators implementing different cgroup strategies. There is no sane > way around requiring "choosing of policies" to happen before > "configuration of chosen policies". This is not just specific to blk-throttle. If in future throttling policy is removable like elevator, then it will be fine to reset the throttling related configuration upon removal of throttling policy. But resetting throttling configuration without policy going anywhere does not sound good. Thanks Vivek