From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com ([209.85.220.54]:64567 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751643AbaIUDio (ORCPT ); Sat, 20 Sep 2014 23:38:44 -0400 Received: by mail-pa0-f54.google.com with SMTP id fb1so2456781pad.13 for ; Sat, 20 Sep 2014 20:38:43 -0700 (PDT) Received: from Akira-Hayakawas-MacBook-Pro.local (e0109-106-188-109-152.uqwimax.jp. [106.188.109.152]) by mx.google.com with ESMTPSA id hb1sm5676325pbd.85.2014.09.20.20.38.41 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 20 Sep 2014 20:38:43 -0700 (PDT) Message-ID: <541E483F.50805@gmail.com> Date: Sun, 21 Sep 2014 12:38:39 +0900 From: Akira Hayakawa MIME-Version: 1.0 Subject: [Question] What if the parameter for --size option is smaller than the target device? Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: fio@vger.kernel.org Hi, I am writing a test with fio tool (2.0.8) and I am facing a problem. I just want to submit 512B random write to a block device. In my case, the size of the device is 2MB and the amount of writes (specified by --size option) is 32MB. like this (A line from device-mapper-test-suite. Is my command wrong?): ProcessControl.run("fio --name=test --filename=#{dev.path} --rw=randwrite --ioengine=libaio --direct=1 --size=#{@param[0]}m --bs=512") The problem is, the runtime is too short. The block device is just a single HDD so, it will be 30sec or so. But it's actually 3sec... My guess is that fio uses min(device size, param to --size) as the amount of writes here. To investigate it, I increased the size of the device to x10 and saw the runtime gets x10. My questions are: 1. Is my guess correct? 2. What shall I do to make fio work as I want it to do? Thanks, - Akira