From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754521AbbCYPlI (ORCPT ); Wed, 25 Mar 2015 11:41:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60279 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754494AbbCYPlE (ORCPT ); Wed, 25 Mar 2015 11:41:04 -0400 Date: Wed, 25 Mar 2015 11:40:22 -0400 From: Vivek Goyal To: Tejun Heo Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, jack@suse.cz, hch@infradead.org, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, lizefan@huawei.com, cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz, clm@fb.com, fengguang.wu@intel.com, david@fromorbit.com, gthelen@google.com Subject: Re: [PATCHSET 1/3 v2 block/for-4.1/core] writeback: cgroup writeback support Message-ID: <20150325154022.GC29728@redhat.com> References: <1427086499-15657-1-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1427086499-15657-1-git-send-email-tj@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 23, 2015 at 12:54:11AM -0400, Tejun Heo wrote: > > > How to test > ----------- > > * Boot with kernel option "cgroup__DEVEL__legacy_files_on_dfl". > > * umount /sys/fs/cgroup/memory > umount /sys/fs/cgroup/blkio > mkdir /sys/fs/cgroup/unified > mount -t cgroup -o __DEVEL__sane_behavior cgroup /sys/fs/cgroup/unified > echo +blkio > /sys/fs/cgroup/unified/cgroup.subtree_control > > * Build the cgroup hierarchy (don't forget to enable blkio using > subtree_control) and put processes in cgroups and run tests on ext2 > filesystems and blkio.throttle.* knobs. > [..] > This patchset is on top of > > block/for-4.1/core bfd343aa1718 ("blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set") > + [1] [PATCH] writeback: fix possible underflow in write bandwidth calculation > > and available in the following git branch. > > git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-cgroup-writeback-20150322 > Hi Tejun, Great Work. I tried to do some basic testing and it seems to work. I used "review-cgroup-writeback-switch-20150322" branch for my testing. I have 32G of RAM on my system and I setup a write bandwidth of 1MB/s on the disk and allowed a dd to run. That dd quickly consumed 5G of page cache before it reached to a steady state. Sounds like too much of cache consumption which will be drained at a speed of 1MB/s. Not sure if this is expected or bdi back-pressure is not being applied soon enough. Thanks Vivek