From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030525Ab2CTLtu (ORCPT ); Tue, 20 Mar 2012 07:49:50 -0400 Received: from merlin.infradead.org ([205.233.59.134]:43011 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030322Ab2CTLtt (ORCPT ); Tue, 20 Mar 2012 07:49:49 -0400 Date: Tue, 20 Mar 2012 12:49:43 +0100 From: Jens Axboe To: Tejun Heo Cc: vgoyal@redhat.com, linux-kernel@vger.kernel.org, ctalbott@google.com, rni@google.com Subject: Re: [PATCHSET] block: remove ioc_*_changed() Message-ID: <20120320114943.GM7505@kernel.dk> References: <1332195059-2750-1-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1332195059-2750-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 19 2012, Tejun Heo wrote: > Hello, guys. > > The changed notification used by cfq is rather odd. cfq caches the > associated cfqqs per cic and uses the changed notification to expire > those lookup caches. > > The explicit notification mechanism might make sense if determining > whether the current cache is up-to-date is difficult or expensive; > however, that isn't the case here. Determining whether ioprio or > cgroup has changed is straight-forward and inexpensive. > > This patchset updates cfq to so that it remembers the current ioprio > and blkcg in the cic and determines whether cfqq's need to be reset > without using the changed notification and drops the changed > notification code. > > 0001-blkcg-add-blkcg-id.patch > 0002-cfq-pass-around-cfq_io_cq-instead-of-io_context.patch > 0003-cfq-don-t-use-icq_get_changed.patch > 0004-block-remove-ioc_-_changed.patch > > 0001 adds unique u64 id to each blkcg so that policies can tell > whether the associated blkcg has changed. > > 0002 makes cfq pass around cic internally instead of ioc. This is a > cleanup in itself and necessary for the next patch. > > 0003 updates cfq to not use changed notification. > > 0004 removes code implementing changed notification. > > This patchset is on top of > > block/for-3.4/core 671058fb2a2aac4e70f01b316b06bc59b98bd138 > + [1] blkcg: fix percpu stat allocation and remove stats_lock, take#2 > > and available in the following git branch > > git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git blk-ioc-remove-changed Thanks Tejun, applied [1] and this one to for-3.4/core. -- Jens Axboe