From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753985AbcGTPbT (ORCPT ); Wed, 20 Jul 2016 11:31:19 -0400 Received: from mail-yw0-f179.google.com ([209.85.161.179]:36347 "EHLO mail-yw0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754236AbcGTPbJ (ORCPT ); Wed, 20 Jul 2016 11:31:09 -0400 Date: Wed, 20 Jul 2016 11:30:52 -0400 From: Tejun Heo To: =?utf-8?B?5byg55yf?= Cc: aaronlee0817@163.com, axboe@kernel.dk, mlin@kernel.org, shli@kernel.org, linux-kernel@vger.kernel.org, cgroup@vger.kernel.org, linux-block@vger.kernel.org, zhen1.zhang@samsung.com, yanzi.zhang@samsung.com, jiale0817.li@samsung.com Subject: Re: Cgroup: iops throttle problem Message-ID: <20160720153052.GE4574@htj.duckdns.org> References: <3aad6640.14fc7.155fe37ba10.Coremail.zhangzhen507@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3aad6640.14fc7.155fe37ba10.Coremail.zhangzhen507@163.com> User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Mon, Jul 18, 2016 at 09:35:12PM +0800, 张真 wrote: > Hello > My name is Zhen Zhang , me and Jiale Li recently test and analyze the cgroup > blkio functions. > We tested the buffered read a file using bio when the > blkio.throttle.read_iops_device is set 1000. > The fio result file displays the iops is 13720 larger than 1000 when blocksize > is 4K in fio. blk-throttle does allow bursts so the iops might go over the set limit for a short period. Over time, it shouldn't be over the set limit. > We set different blocksize in fio: > 4K, 8K , 16K, 32K, 64K, 128K, 256K, 512K, 1024K > > The iops in fio: > 13035, 7258, 3711, 1698, 907, 460, 228, 102, 54 Looks like you were hitting the natural bandwidth limit of the device. > When bs is less than 64K, the iops is larger than 1000, when bs is larger than > 64K, the iops is less than 1000. > We tested it on ubuntu 16.04 with kernel 4.4.0 > > Dose this a problem of blkio iops throttle? I don't know how the test was run but consistently going over the set limit isn't the expected behavior. Thanks. -- tejun