From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753473AbbAWIAj (ORCPT ); Fri, 23 Jan 2015 03:00:39 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:2847 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751942AbbAWIAh (ORCPT ); Fri, 23 Jan 2015 03:00:37 -0500 Message-ID: <54C1FF44.1090902@huawei.com> Date: Fri, 23 Jan 2015 15:59:00 +0800 From: "Ouyang Zhaowei (Charles)" User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: =?UTF-8?B?Um9nZXIgUGF1IE1vbm7DqQ==?= CC: , , , Subject: xen-blkfront: weird behavior of "iostat" after VM live-migrate which xen-blkfront module has indirect descriptors Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.30.65] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020202.54C1FF55.0183,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 105b6262ecf276f5c83705b5f15d9c47 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Roger, We are testing the indirect feature of xen-blkfront module these days. And we found that, after VM live-migrate a couple of times, the "%util" of iostat keeps being 100%, and there are several requests stock in "avgqu-sz". We have checked some later version of Linux, and it happens on Ubuntu 14.04, Ubuntu 14.10 and RHEL 7.0. The iostat shows like below: avg-cpu: %user %nice %system %iowait %steal %idle 0.00 0.00 0.00 0.00 0.00 100.00 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util xvda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.00 0.00 0.00 0.00 0.00 100.00 dm-0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Could you tell us that why is this happening, is this a bug? Thanks! Ouyang Zhaowei