From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: Intel X25-M MLC SSD benchmarks Date: Wed, 10 Dec 2008 20:44:24 -0700 Message-ID: <20081211034423.GA26095@parisc-linux.org> References: <20081210213937.GC25548@parisc-linux.org> <83CA05F64804AF43B8F733C4ABDFAA51022D04D7@mail1.bitband.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:47746 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751027AbYLKDol (ORCPT ); Wed, 10 Dec 2008 22:44:41 -0500 Content-Disposition: inline In-Reply-To: <83CA05F64804AF43B8F733C4ABDFAA51022D04D7@mail1.bitband.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Raz Ben-Yehuda Cc: linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org On Thu, Dec 11, 2008 at 12:12:37AM +0200, Raz Ben-Yehuda wrote: > I did not want to dive into details because it does not matter. Whether > noop,deadline, deadline parameters... > As for the controller I used 4 different controllers. Adaptec,AHCI and > Intel as Integrated chips on the 1025W-UR supermicro motherboard, and a > 4-th controller SuperMicro UIO Adaptec aac card. > All gave same results for most dd writes commands. > dd if=/dev/zero of=/dev/sda bs=1M count=1000 oflag=direct , and many > other variants such erase block size ( 128K ) , several erase block size > and so on. Kernel is 2.6.18-8.el5. OK, I suspect you aren't giving the drive enough work to do for it to perform at its best. Try doing something like this: for i in $(seq 0 9); do \ dd if=/dev/zero of=/dev/sda bs=1M count=1000 oflag=direct \ seek=$(($i * 1000)) & \ done > I used all on a supermicro 1025W-UR. Disks have a SAS interface, 80GB. > Also, I would like to note, I have 8 disks in array, while each one > perform READS 250 MB/s, together I degrade to 200 MB/s each. As for That doesn't surprise me; you're probably hitting a limitation either of the array or the cable itself. A SAS cable can run up to 6Gbps, which will be around 600MB/s. So three drives should be able to saturate your SAS cable. If you're using an x4 link, that goes up to 2400MB/s which should be ample for 8 drives ... maybe you're using a 3Gbps cable which would limit each drive to 150MB/s. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."