From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4FB6583B.4050708@redhat.com> Date: Fri, 18 May 2012 22:10:03 +0800 From: Asias He MIME-Version: 1.0 Subject: Re: Why fio triggers reading of device serial number References: <4FB5EA0D.7030402@redhat.com> <4FB5EC0B.7010304@redhat.com> <4FB61DD8.7020800@kernel.dk> In-Reply-To: <4FB61DD8.7020800@kernel.dk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit To: Jens Axboe Cc: fio@vger.kernel.org List-ID: On 05/18/2012 06:00 PM, Jens Axboe wrote: > 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. OK. Thanks, Jens. -- Asias