From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: Performance of SCST versus STGT Date: Thu, 17 Jan 2008 13:34:46 +0300 Message-ID: <478F2F46.9040103@vlnb.net> References: <20080117184052F.fujita.tomonori@lab.ntt.co.jp> <478F246C.4040400@vlnb.net> <20080117190558K.fujita.tomonori@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080117190558K.fujita.tomonori-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: stgt-devel-bounces-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org Errors-To: stgt-devel-bounces-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org To: FUJITA Tomonori Cc: James.Bottomley-JuX6DAaQMKPCXq6kfMZ53/egYHeGw8Jk@public.gmane.org, stgt-devel-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org, linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, scst-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-scsi@vger.kernel.org FUJITA Tomonori wrote: > On Thu, 17 Jan 2008 12:48:28 +0300 > Vladislav Bolkhovitin wrote: > > >>FUJITA Tomonori wrote: >> >>>On Thu, 17 Jan 2008 10:27:08 +0100 >>>"Bart Van Assche" wrote: >>> >>> >>> >>>>Hello, >>>> >>>>I have performed a test to compare the performance of SCST and STGT. >>>>Apparently the SCST target implementation performed far better than >>>>the STGT target implementation. This makes me wonder whether this is >>>>due to the design of SCST or whether STGT's performance can be >>>>improved to the level of SCST ? >>>> >>>>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 >>>> >>>>These results show that SCST uses the InfiniBand network very well >>>>(effectivity of about 88% via SRP), but that the current STGT version >>>>is unable to transfer data faster than 82 MB/s. Does this mean that >>>>there is a severe bottleneck present in the current STGT >>>>implementation ? >>> >>> >>>I don't know about the details but Pete said that he can achieve more >>>than 900MB/s read performance with tgt iSER target using ramdisk. >>> >>>http://www.mail-archive.com/stgt-devel-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org/msg00004.html >> >>Please don't confuse multithreaded latency insensitive workload with >>single threaded, hence latency sensitive one. > > > Seems that he can get good performance with single threaded workload: > > http://www.osc.edu/~pw/papers/wyckoff-iser-snapi07-talk.pdf 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? > But I don't know about the details so let's wait for Pete to comment > on this. I added him on CC > Perhaps Voltaire people could comment on the tgt iSER performances. >