Date: Mon, 8 Sep 1997 03:06:47 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: ahd@kew.com (Drew Derbyshire) Cc: roberto@keltia.freenix.fr, current@FreeBSD.ORG Subject: Re: lousy disk perf. under cpu load (was IDE vs SCSI) Message-ID: <199709080306.UAA16822@usr07.primenet.com> In-Reply-To: <341344B3.57D10484@kew.com> from "Drew Derbyshire" at Sep 7, 97 08:20:03 pm
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> Because you can take an EIDE drive and put it on a system with 1990 > vintage IDE controller, and only take a performance hit. Upward > compatibility means a lot to any user. I have a 1994 vintage IDE controller. It is a CMD640B. I take a bit more than a performance hit. Unfortunately, the thing is welded to my motherboard. I have a 1990 vintage IDE controller. It has no buffers between it and the ISA connector. I take a bit more than a performance hit. Sure, it's possible to work around the first (not the second, though) in software. Between the CMD640B and the flawed Intel IDE chipset, we are talking about more than 60% of the E/IDE systems in existance. > This reminds me of the "Turning PC into workstations" line at the top of > the FreeBSD home page. To beat NT Workstation at it's own game, you > have beat on it's own hardware. Do you want to turn the maximum number > of systems (embracing the most common PC hard drive and CD-ROM types) > into workstations? Or make them _think_ their EIDE hard drive and ATAPI > CD-ROM _limits_ them from turning their PC into a FreeBSD Workstation? The E/IDE CDROM on channel 2 of my CDM640B system will not function correctly under NT. I can make if function under Windows 95 only by going into the "Advanced..." button of the "Performance" tab of the "Properties" page for "My Computer" and disabling protected mode disk interrupt handling and 32 bit Protected mode disk drivers (my BIOS on that machine does not have the necessary option to workaround the bug, and it's not Flashable). > To me, the entire "SCSI rules" tone some people use reminds of Mac > users, and I don't want think most people on this list wish for Bill > Gates to want or need to bail out FreeBSD. :-) This is not an issue of the software refusing to work with some hardware; it is an issue of some hardware being flawed by design. In some cases there are workarounds. In others, the hardware is simply too flawed. DOS works because, as a real mode non-reeentrant interrupt handler, it doesn't issue commands so fast that a unbuffered data latch on an ISA bus doesn't cause it problems. You could achieve the same thing in BSD by hitting the "Turbo" button to turn your 200MHz Pentime Pro into an 8MHz AT. Or FreeBSD could work around that in software, too, by putting in buzz-loops to the effect that the machine turns into an 8MHz AT "only" during disk accesses. As far as a "bailout" by Bill of FreeBSD, I'm sure Jordan would be happy to go public and sell him $180,000,000 in non-voting stock in FreeBSD, Inc., just as Bill has $180,000,000 in non-voting stock in Apple, Inc.. 8-) 8-). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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