From owner-freebsd-arm@FreeBSD.ORG Sat Mar 5 12:49:09 2011 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 35E5D1065670 for ; Sat, 5 Mar 2011 12:49:09 +0000 (UTC) (envelope-from ticso@cicely7.cicely.de) Received: from raven.bwct.de (raven.bwct.de [85.159.14.73]) by mx1.freebsd.org (Postfix) with ESMTP id 9CC968FC1B for ; Sat, 5 Mar 2011 12:49:08 +0000 (UTC) Received: from mail.cicely.de ([10.1.1.37]) by raven.bwct.de (8.13.4/8.13.4) with ESMTP id p25Cn1aQ060670 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sat, 5 Mar 2011 13:49:02 +0100 (CET) (envelope-from ticso@cicely7.cicely.de) Received: from cicely7.cicely.de (cicely7.cicely.de [10.1.1.9]) by mail.cicely.de (8.14.4/8.14.4) with ESMTP id p25Cmo98043530 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 5 Mar 2011 13:48:50 +0100 (CET) (envelope-from ticso@cicely7.cicely.de) Received: from cicely7.cicely.de (localhost [127.0.0.1]) by cicely7.cicely.de (8.14.2/8.14.2) with ESMTP id p25CmooL043354; Sat, 5 Mar 2011 13:48:50 +0100 (CET) (envelope-from ticso@cicely7.cicely.de) Received: (from ticso@localhost) by cicely7.cicely.de (8.14.2/8.14.2/Submit) id p25CmnBO043353; Sat, 5 Mar 2011 13:48:49 +0100 (CET) (envelope-from ticso) Date: Sat, 5 Mar 2011 13:48:49 +0100 From: Bernd Walter To: Ian Lepore Message-ID: <20110305124849.GW86812@cicely7.cicely.de> References: <201103042020.p24KKBL7007848@freefall.freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201103042020.p24KKBL7007848@freefall.freebsd.org> X-Operating-System: FreeBSD cicely7.cicely.de 7.0-STABLE i386 User-Agent: Mutt/1.5.11 X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED=-1, BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 autolearn=unavailable version=3.3.0 X-Spam-Checker-Version: SpamAssassin 3.3.0 (2010-01-18) on spamd.cicely.de Cc: freebsd-arm@freebsd.org Subject: Re: arm/155214: [patch] MMC/SD IO slow on Atmel ARM with modern large SD cards X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: ticso@cicely.de List-Id: Porting FreeBSD to the StrongARM Processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 05 Mar 2011 12:49:09 -0000 On Fri, Mar 04, 2011 at 08:20:11PM +0000, Ian Lepore wrote: > The following reply was made to PR arm/155214; it has been noted by GNATS. > > From: Ian Lepore > To: ticso@cicely.de > Cc: FreeBSD-gnats-submit@freebsd.org > Subject: Re: arm/155214: [patch] MMC/SD IO slow on Atmel ARM with modern > large SD cards > Date: Fri, 04 Mar 2011 13:10:12 -0700 > > On Thu, 2011-03-03 at 00:52 +0100, Bernd Walter wrote: > > On Wed, Mar 02, 2011 at 02:53:18PM -0700, Ian Lepore wrote: > Since 15mhz/4bit is still twice the data throughput of 30mhz/1bit I > decided to do some crude benchmarking to see if it's worth the trouble > of making 4-bit work correctly. The results appear below. In > summary, there is definitely a benefit to using 4-bit transfers, but > the improvement isn't nearly as dramatic as the change from single- to > multi-block IO. 4bit transport has a more interesting point than bandwidth. An 64k read with 15MHz/1bit will have ~35ms calculated latency just for the data transport, which I consider a pretty high value. Nevertheless I'm still exited about your multiblock support and your measured values already look fantastic. > Based on the benchmark results, and the fact that I don't really have > the time to take on the dev/mmc changes right now, I think we should > adopt the multi-block patches and stick with 30mhz/1-bit for now. I completely agree with you. The main problem was write performance and this is clearly solved to match with media capabilities - not to speak that the former single block writes also had an increased media wear. -- B.Walter http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.