Subject: Re: ballpark ratio users:cpu for a 86 NetBSD box?
To: None <current-users@NetBSD.ORG>
From: Mike Miscevic <email@example.com>
Date: 09/28/1994 12:27:03
On Wed, 28 Sep 1994, John F. Woods wrote:
> This is getting way off topic, but I'd like to make a couple of observations,
> if for no other reason than to cheer up the owners of non-Intel systems :-).
> Running a big multi-user system isn't just a matter of CPU speed, unless
> all your users are doing nothing but using xv to look at JPEG images.
> Delivered disk bandwidth is a crucial part of *most* multi-user mixes,
> and that's something that expensive workstations have generally supplied
> much better than PCs have (and PCI or no PCI, I'll believe that a given
> PC has a *controller* that delivers better performance when I see a real
> benchmark run on it).
> As an unusual example of this effect, when I brought up my NetBSD system
> full time, it was replacing an ancient CRDS Universe system, which contained
> a 12.5MHz 68020 central processor (and a 10MHz 68000 handling 12 serial
> ports). According to dhrystone, the new system was approximately ten times
> the horsepower of the old system (and the memory system was at least four
> times the speed, too, another important thing that often gets lost in
> clock-size wars). Yet as purchased, my 486/33 had great difficulty keeping
> up with the Universe system doing 38.4KB SLIP, and the Universe was still
> handling the modem at the time. (There have been improvements in NetBSD's
> driver software since then, so *maybe* it would now be a fair match :-).
Different people define "fair" in different ways...
So *maybe* you should buy equivalent multi-serial port hardware for the
NetBSD system before you make such an observation. Maybe something that
wouldn't generate an interrupt for each byte that it received? Can we say
hardware buffer? Now that would be a fair match :)
> And, of course, if I had actually been using all twelve serial ports, it
> would have been quite difficult to have matched the capability of the
> Universe. (And if I had maxed out the Universe at 68 ports?) Horsepower
> just isn't enough to make up for cripplingly braindamaged I/O design.
> Fortunately for the PC side of this argument, the CRDS Versabus SCSI channel
> board was really slow, so my disk bandwidth improved quite a bit :-). Though
> not by a factor of ten.
Mike Miscevic | net: firstname.lastname@example.org | Opinions expressed by
Rm 550, 160 Elgin St. | tel: (613) 781-4361 | me are not necessarily
Ottawa, Ont. K2P 2C4 | fax: (613) 238-7772 | those of my employer.