From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Re: [PATCHSET 1/3 v2 block/for-4.1/core] writeback: cgroup writeback support Date: Wed, 25 Mar 2015 11:40:22 -0400 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 Cc: axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jack-AlSwsSmVLrQ@public.gmane.org, hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, mhocko-AlSwsSmVLrQ@public.gmane.org, clm-b10kYP2dOMg@public.gmane.org, fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org, gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org To: Tejun Heo Return-path: Content-Disposition: inline In-Reply-To: <1427086499-15657-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.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