From owner-freebsd-scsi@FreeBSD.ORG Thu Apr 29 23:25:25 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 18BE916A4CF for ; Thu, 29 Apr 2004 23:25:25 -0700 (PDT) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id A05FC43D4C for ; Thu, 29 Apr 2004 23:25:23 -0700 (PDT) (envelope-from scottl@freebsd.org) Received: from freebsd.org (g4.samsco.home [192.168.0.12]) by pooker.samsco.org (8.12.10/8.12.10) with ESMTP id i3U6Sxu6092842; Fri, 30 Apr 2004 00:28:59 -0600 (MDT) (envelope-from scottl@freebsd.org) Message-ID: <4091F11A.8010605@freebsd.org> Date: Fri, 30 Apr 2004 00:24:26 -0600 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7a) Gecko/20040214 X-Accept-Language: en-us, en MIME-Version: 1.0 To: "J.D. Bronson" References: <6.1.0.6.2.20040429063234.024493d8@localhost> In-Reply-To: <6.1.0.6.2.20040429063234.024493d8@localhost> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=0.0 required=3.8 tests=none autolearn=no version=2.63 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on pooker.samsco.org cc: freebsd-scsi@freebsd.org Subject: Re: AHC_ALLOW_MEMIO 5.2.1 X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Apr 2004 06:25:25 -0000 J.D. Bronson wrote: > >Date: Wed, 28 Apr 2004 23:12:18 -0600 > >From: Scott Long > >User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; > >rv:1.7a) Gecko/20040214 > >To: Andy Farkas > >CC: "J.D. Bronson" , freebsd-scsi@freebsd.org > >Subject: Re: AHC_ALLOW_MEMIO 5.2.1 > > > >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. > > > >Scott > > Could it be possible to add a comment line to the driver so that if one > enabled MEMIO, that dmesg could reflect that it was using MEMIO or not? > > Right now, if I enable it - I cannot tell (to my knowledge) that it is > working or not. > > Thanks! > > Enable bootverbose. Scott