From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mondschein.lichtvoll.de ([194.150.191.11]:39053 "EHLO mail.lichtvoll.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753621Ab1HCUdy (ORCPT ); Wed, 3 Aug 2011 16:33:54 -0400 From: Martin Steigerwald Subject: Re: Measuring IOPS Date: Wed, 3 Aug 2011 22:33:52 +0200 References: <201107291737.40463.Martin@lichtvoll.de> <201108032131.36188.Martin@lichtvoll.de> (sfid-20110803_222903_776209_B9762BAA) In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201108032233.52591.Martin@lichtvoll.de> Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Jeff Moyer Cc: fio@vger.kernel.org Am Mittwoch, 3. August 2011 schrieb Jeff Moyer: > Martin Steigerwald writes: > > - ioengine=libaio > > - direct=1 > > - and then due to direct I/O alignment requirement: bsrange=2k-16k > > > > So I now also fully understand that ioengine=sync just refers to the > > synchronous nature of the system calls used, not on whether the I/Os > > are issued synchronously via sync=1 or by circumventing the page > > cache via direct=1 > > > > Attached are results that bring down IOPS on read drastically! I > > first let sequentiell.job write out the complete 2 gb with random > > data and then ran the iops.job. > > If you want to measure the maximum iops, then you should consider > driving iodepths > 1. Assuming you are testing a sata ssd, try using a > depth of 64 (twice the NCQ depth). Yes, I thought about that too, but then also read about the "recommendation" to use an iodepth of one in a post here: http://www.spinics.net/lists/fio/msg00502.html What will be used in regular workloads - say Linux desktop on an SSD here? I would bet that Linux uses what it can get? What about server workloads like mail processing on SAS disks or fileserver on SATA disks and such like? Twice of merkaba:~> hdparm -I /dev/sda | grep -i queue Queue depth: 32 * Native Command Queueing (NCQ) ? Why twice? Thanks, -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7