From owner-freebsd-scsi@FreeBSD.ORG Fri Jun 4 09:56:09 2004 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 15EED16A4CE; Fri, 4 Jun 2004 09:56:09 -0700 (PDT) Received: from srv1.cosmo-project.de (srv1.cosmo-project.de [213.83.6.106]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3C34743D55; Fri, 4 Jun 2004 09:56:08 -0700 (PDT) (envelope-from ticso@cicely12.cicely.de) Received: from cicely5.cicely.de (cicely5.cicely.de [IPv6:3ffe:400:8d0:301:200:92ff:fe9b:20e7]) (authenticated bits=0) i54Gu1aI031616 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=OK); Fri, 4 Jun 2004 18:56:04 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (cicely12.cicely.de [IPv6:3ffe:400:8d0:301::12]) by cicely5.cicely.de (8.12.10/8.12.10) with ESMTP id i54GsuUi033745 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 4 Jun 2004 18:54:56 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (localhost [127.0.0.1]) by cicely12.cicely.de (8.12.11/8.12.11) with ESMTP id i54GsuZb085425; Fri, 4 Jun 2004 18:54:56 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: (from ticso@localhost) by cicely12.cicely.de (8.12.11/8.12.11/Submit) id i54GsssT085424; Fri, 4 Jun 2004 18:54:54 +0200 (CEST) (envelope-from ticso) Date: Fri, 4 Jun 2004 18:54:54 +0200 From: Bernd Walter To: Scott Long Message-ID: <20040604165453.GF51677@cicely12.cicely.de> References: <6.1.0.6.2.20040428074703.024548b8@localhost> <20040429135222.L64510@hewey.af.speednet.com.au> <40908EB2.4090803@freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <40908EB2.4090803@freebsd.org> X-Operating-System: FreeBSD cicely12.cicely.de 5.2-CURRENT alpha User-Agent: Mutt/1.5.6i X-Spam-Status: No, hits=-4.9 required=3.0 tests=BAYES_00 autolearn=ham version=2.61 X-Spam-Report: * -4.9 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] X-Spam-Checker-Version: SpamAssassin 2.61 (1.212.2.1-2003-12-09-exp) on cicely5.cicely.de cc: freebsd-scsi@freebsd.org cc: Andy Farkas Subject: Re: AHC_ALLOW_MEMIO 5.2.1 X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: ticso@cicely.de List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Jun 2004 16:56:09 -0000 On Wed, Apr 28, 2004 at 11:12:18PM -0600, Scott Long wrote: > Andy Farkas wrote: > > >On Wed, 28 Apr 2004, J.D. Bronson wrote: > > > > > >>What happened to this kernel option on 5.2.1? > >> > >>AHC_ALLOW_MEMIO > >> > >> > >>It does not seem to be in any file at all anymore? > >> > >> -JDB > > > > > >Its in /sys/conf/NOTES :) > > > >The generated file opt_aic7xxx.h will contain it. > > > >I sometimes enable this option in my kernels. Whether it does anything or > >not (performance-wise or other), I don't know. > > > > On x86, MEMIO is generally faster and causes the CPU to spin less than > IOPORT cycles do. It can result in a minor but measurable speed > difference, though the effects of HyperThreading, when in use, could > offset the benefits. In any case, the reason that this option exists > is to work around motherboards that incorrectly do write-combining on > MEMIO registers, something that most ahc/ahd chips do not support nor > handle well. We added a somewhat sophisticated runtime test for this > to the driver last year, so there really isn't a reason to not enable > the option. If you do and the test detects problems, it will > automatically throttle back to IOPORT. We should probably just remove > the option all-together, and just use the sysctl/tunable as a backup in > case problems develope. The write combining might be a good explanation why I never had success with ahc controllers on several different alpha models. I will check for this. Alpha CPUs don't know about IO and setup IO space from normal memory address range on their primary busses, however behind PCI-PCI bridges only memory space is available. Non bridged controllers tend to fail after some usage and the memory range probing fails most of the time. -- B.Walter BWCT http://www.bwct.de bernd@bwct.de info@bwct.de