From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from casper.infradead.org ([85.118.1.10]:54219 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754113Ab2ERKBT (ORCPT ); Fri, 18 May 2012 06:01:19 -0400 Message-ID: <4FB61DD8.7020800@kernel.dk> Date: Fri, 18 May 2012 12:00:56 +0200 From: Jens Axboe MIME-Version: 1.0 Subject: Re: Why fio triggers reading of device serial number References: <4FB5EA0D.7030402@redhat.com> <4FB5EC0B.7010304@redhat.com> In-Reply-To: <4FB5EC0B.7010304@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Asias He Cc: fio@vger.kernel.org On 05/18/2012 08:28 AM, Asias He wrote: > Hi, List > > I noticed that fio triggers reading of device serial number when fio > starts (one read) and stops (lots of read). I was wondering if fio was > reading the sysfs attribute directly in fio's code, > e.g./sys/block/vda/serial, or it triggered something which make udevd to > read it. > > trace-cmd shows it seems udevd is reading: > > udevd-6856 [006] xxx: function: dev_attr_show > udevd-6856 [006] xxx: function: virtblk_serial_show > > Any ideas? Thanks. Probably mtime changing of the special file inode, causing some udev rule to attempt to re-read the id/serial. Fio doesn't read the serial number. -- Jens Axboe