From mboxrd@z Thu Jan 1 00:00:00 1970 From: "tj@kernel.org" Subject: Re: [Lsf-pc] [LSF/MM ATTEND] Filesystems -- Btrfs, cgroups, Storage topics from Facebook Date: Thu, 2 Jan 2014 11:14:06 -0500 Message-ID: <20140102161406.GI11501@htj.dyndns.org> References: <1388439412.16965.27.camel@ret> <20131231084927.GA29449@gmail.com> <20131231124535.GE11920@quack.suse.cz> <1388495991.16965.36.camel@ret> <52C2D342.8000606@tao.ma> <1388504116.24668.0.camel@ret.masoncoding.com> <20140102064659.GF11920@quack.suse.cz> <1388676106.24668.14.camel@ret.masoncoding.com> <20140102160102.GH11501@htj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "jack@suse.cz" , "vgoyal@redhat.com" , "lizefan@huawei.com" , "gnehzuil.liu@gmail.com" , "tm@tao.ma" , "lsf-pc@lists.linux-foundation.org" , "linux-fsdevel@vger.kernel.org" To: Chris Mason Return-path: Received: from mail-qa0-f51.google.com ([209.85.216.51]:45830 "EHLO mail-qa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751753AbaABQOK (ORCPT ); Thu, 2 Jan 2014 11:14:10 -0500 Received: by mail-qa0-f51.google.com with SMTP id o15so13326444qap.17 for ; Thu, 02 Jan 2014 08:14:09 -0800 (PST) Content-Disposition: inline In-Reply-To: <20140102160102.GH11501@htj.dyndns.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hey, again. On Thu, Jan 02, 2014 at 11:01:02AM -0500, tj@kernel.org wrote: > What we're missing is a way to make such split visible in the upper > layers for writeback. It seems rather clear to me that that's the > right way to approach the problem rather than implementing separate > control for writebacks and somehow coordinate that with the rest. To clarify a bit. I think what we need to do is splitting bdi's for each active blkcg (at least the part which is relevant to propagating io pressure upwards). I really don't think a scheme where we try to somehow split bandwidth number between two separate enforcing mechanisms is something we should go after. Thanks. -- tejun