From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 3/3] writeback, blkio: add documentation for cgroup writeback support Date: Tue, 16 Jun 2015 17:54:36 -0400 Message-ID: <20150616215436.GE22637@mtj.duckdns.org> References: <1434146254-26220-1-git-send-email-tj@kernel.org> <1434146254-26220-4-git-send-email-tj@kernel.org> <20150615172823.GA5783@redhat.com> <20150615182345.GB18517@mtj.duckdns.org> <20150615233519.GB30059@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Theodore Ts'o , Vivek Goyal , axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: Content-Disposition: inline In-Reply-To: <20150615233519.GB30059-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.vger.kernel.org Hello, Ted. On Mon, Jun 15, 2015 at 07:35:19PM -0400, Theodore Ts'o wrote: > So if there is some way we can signal to any cgroup that that might be > throttling writeback or disk I/O that the jbd/jbd2 process should be > considered privileged, that would be a good since it would allow us to > avoid a potential priority inversion problem. I see. In the long term, I think we might need to come up with a way to overcharge a slower cgroup to avoid blocking faster ones for cases where some IOs are depended upon by more than one cgroups. That'd take quite a bit of work from blkcg side. Will think more about it. Thanks. -- tejun