From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: [Scst-devel] [Stgt-devel] Performance of SCST versus STGT Date: Thu, 17 Jan 2008 16:44:31 +0300 Message-ID: <478F5BBF.3080905@vlnb.net> References: <20080117184052F.fujita.tomonori@lab.ntt.co.jp> <478F246C.4040400@vlnb.net> <20080117190558K.fujita.tomonori@lab.ntt.co.jp> <478F2F46.9040103@vlnb.net> <20080117122956.GA3567@porcupine.cita.utoronto.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-relay-01.mailcluster.net ([77.221.130.213]:47222 "EHLO mail-relay-01.mailcluster.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750952AbYAQNod (ORCPT ); Thu, 17 Jan 2008 08:44:33 -0500 In-Reply-To: <20080117122956.GA3567@porcupine.cita.utoronto.ca> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Robin Humble Cc: FUJITA Tomonori , James.Bottomley@hansenpartnership.com, scst-devel@lists.sourceforge.net, stgt-devel@lists.berlios.de, linux-scsi@vger.kernel.org Robin Humble wrote: > On Thu, Jan 17, 2008 at 01:34:46PM +0300, Vladislav Bolkhovitin wrote: > >>Hmm, I can't find which IB hardware did he use and it's declared Gbps >>speed. He declared only "Mellanox 4X SDR, switch". What does it mean? > > > SDR is 10Gbit carrier, at most about ~900MB/s data rate. > DDR is 20Gbit carrier, at most about ~1400MB/s data rate. Thanks. Then the single threaded rate with one outstanding command between SCST SRP on 8Gbps link vs STGT iSRP on 10Gbps link (according to that paper) is 600MB/s vs ~480MB/s (page 26). Still SCST based target is about 60% faster. > On Thu, 17 Jan 2008 10:27:08 +0100 "Bart Van Assche" wrote: > >>Test performed: read 2 GB of data in blocks of 1 MB from a target (hot >>cache -- no disk reads were performed, all reads were from the cache). >>Test command: time dd if=/dev/sde of=/dev/null bs=1M count=2000 >> >> STGT read SCST read >> performance (MB/s) performance (MB/s) >>Ethernet (1 Gb/s network) 77 89 >>IPoIB (8 Gb/s network) 82 229 >>SRP (8 Gb/s network) N/A 600 >>iSER (8 Gb/s network) 80 N/A > > > it kinda looks to me like the tgt iSER tests were waaay too slow to be > using RDMA :-/ > I use tgt to get 500MB/s writes over iSER DDR IB to real files (not > ramdisk). Reads are a little slower, but that changes a bit with distro > vs. mainline kernels.