From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763314Ab3ECS56 (ORCPT ); Fri, 3 May 2013 14:57:58 -0400 Received: from mail-ye0-f170.google.com ([209.85.213.170]:48064 "EHLO mail-ye0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763256Ab3ECS54 (ORCPT ); Fri, 3 May 2013 14:57:56 -0400 Date: Fri, 3 May 2013 11:57:51 -0700 From: Tejun Heo To: Vivek Goyal Cc: Jens Axboe , lkml , Li Zefan , containers@lists.linux-foundation.org, Cgroups Subject: Re: [PATCHSET] blk-throttle: implement proper hierarchy support Message-ID: <20130503185751.GA22860@mtj.dyndns.org> References: <20130502175701.GL19814@mtj.dyndns.org> <20130502181747.GH30020@redhat.com> <20130502182933.GN19814@mtj.dyndns.org> <20130502184514.GI30020@redhat.com> <20130502184953.GP19814@mtj.dyndns.org> <20130502190732.GK30020@redhat.com> <20130502193139.GL30020@redhat.com> <20130502231307.GT19814@mtj.dyndns.org> <20130503175652.GB6062@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130503175652.GB6062@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 On Fri, May 03, 2013 at 01:56:52PM -0400, Vivek Goyal wrote: > > Yeah, I think that's what *should* be happening but not what I'm > > seeing. I'm seeing ~15% penalty. > > What test are you running. I am running a simple dd with directIO and > I am not seeing any penalty. Combination of dd and a test program that I've been using for some while which can generate concurrent direct random IOs. Attaching the source code for the latter. > # set limit to 1000000 bytes/second both in parent and child cgroup > # dd if=/dev/vdb of=/dev/null iflag=direct > > I will capture blktrace and analyze it though to understand better > what's happening. Try using larger block size. It looks like dispatch windows being reset depending on timing is hurting the overall bandwidth. It becomes pronounced with larger IOs. Thanks. -- tejun