From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: Performance of SCST versus STGT Date: Mon, 21 Jan 2008 15:07:40 +0300 Message-ID: <47948B0C.7020702@vlnb.net> References: <20080117184052F.fujita.tomonori@lab.ntt.co.jp> <478F246C.4040400@vlnb.net> <20080117190558K.fujita.tomonori@lab.ntt.co.jp> <20080117174542.GC29650@osc.edu> <479096D2.8090003@vlnb.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: 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: Bart Van Assche Cc: James.Bottomley-JuX6DAaQMKPCXq6kfMZ53/egYHeGw8Jk@public.gmane.org, stgt-devel-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org, linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, FUJITA Tomonori , scst-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-scsi@vger.kernel.org Bart Van Assche wrote: > On Jan 18, 2008 1:08 PM, Vladislav Bolkhovitin wrote: > >>[ ... ] >>So, seems I understood your slides correctly: the more valuable data for >>our SCST SRP vs STGT iSER comparison should be on page 26 for 1 command >>read (~480MB/s, i.e. ~60% from Bart's result on the equivalent hardware). > > > At least in my tests SCST performed significantly better than STGT. > These tests were performed with the currently available > implementations of SCST and STGT. Which performance improvements are > possible for these projects (e.g. zero-copying), and by how much is it > expected that these performance improvements will increase throughput > and will decrease latency ? Sure, zero-copying cache support is well possible for SCST and hopefully will be available soon. The performance (throughput) improvement will depend from used hardware and data access pattern, but the upper bound estimation can be made knowing memory copy throughput on your system (1.6GB/s according to your measurements). For 10Gbps link with 0.9GB/s wire speed it should be up to 30%, for 20Gbps link with wire speed 1.5GB/s (PCI-E 8x limitation) - something up to 70-80%. Vlad