From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761942Ab3EBSuB (ORCPT ); Thu, 2 May 2013 14:50:01 -0400 Received: from mail-qe0-f54.google.com ([209.85.128.54]:52527 "EHLO mail-qe0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761824Ab3EBSt7 (ORCPT ); Thu, 2 May 2013 14:49:59 -0400 Date: Thu, 2 May 2013 11:49:53 -0700 From: Tejun Heo To: Vivek Goyal Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, lizefan@huawei.com, containers@lists.linux-foundation.org, cgroups@vger.kernel.org Subject: Re: [PATCHSET] blk-throttle: implement proper hierarchy support Message-ID: <20130502184953.GP19814@mtj.dyndns.org> References: <1367455189-6957-1-git-send-email-tj@kernel.org> <20130502173428.GA4771@redhat.com> <20130502175701.GL19814@mtj.dyndns.org> <20130502181747.GH30020@redhat.com> <20130502182933.GN19814@mtj.dyndns.org> <20130502184514.GI30020@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130502184514.GI30020@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, May 02, 2013 at 02:45:14PM -0400, Vivek Goyal wrote: > I did not understand this point. In flat model, application issuing > at configured page will not get penalized. > > This penalty is coming from the fact that we are moving bios after the > wait and make them wait in another queue. > > In flat model there is no such problem. So to me, it is the problem > of how hierarchical scheduling is implemented. In flat model, I did > not have to deal with it. But seen from the parent, the child isn't different from any other issuer in flat hierarchy. It's just being repeated, so if you assume a process which behaves in the exact same manner, that process would get penalized too. e.g. imagine an application which throttles itself and issues exactly 1MB/s amount of data in direct IO. It'd get penalized the same way, right? > Ok. Not having a perfect algorithm now is fine. We can always redo it > later. I think we can do source-based RR on bio_lists[] fetching which is simple enough and should be able to avoid most of the problems, right? Thanks. -- tejun