Date: Thu, 16 Sep 1999 21:40:29 -0400 (AST) From: Ian Grigg <iang@systemics.com> To: freebsd-smp@FreeBSD.ORG, somsky@annwn.phys.washington.edu Subject: Re: Examples of FreeBSD SMP success? Message-ID: <199909170140.VAA05868@systemics.com> In-Reply-To: <19990916171751.A19950@annwn.phys.washington.edu>
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Back in the 80's I once worked on a job to install a biggish
unix box into a Quango [1]. It fairly quickly became apparent
that:
1. multi-cpus were more expensive than singles,
when adjusted for overall performance.
2. the cost of the project exceeded the cost of
the hardware.
Under those conditions, even thought the ticket price
of the singles was better, I justified to the bean counters
that multi was superior because they wouldn't have to pay for
another replacement project in 1 year's time [2]. We bought
a Sequent, which effectively projected a 5 year useful life
rather than 2 years, thus saving 1.5 project costs.
I.e., multi-cpus are more expensive, unless you face some
bureaucratic cost as well, in which case they will pay for
themselves over the extended project life.
That was then. Now, you can get dual for a bit more than
the price of single [3]. So, assuming 2 cpus, factor 1 is no
longer relevant. I've been specifying and buying duals for
about a year now, and about half of them are running with
dual cpus [4]. I've got the peace of mind knowing that for
the other half, they'll still be good machines in 2 years [5].
You're mad if you don't buy duals, even if you don't use
the extra slot. There is more time spent in getting them
twining, and there *are* some instabilities, as mentioned
on the group from time to time. But, 2x500 is way better
than 1x500 in a year's time when all the niggles are
forgotten, performance is at 1.9, but your budget doesn't
support any more machines.
iang
[1] Quasi-autonomous national government agency.
[2] project time was one year!
[3] following comments don't apply to quads and up.
[4] duals run FreeBSD and Linux. singles are m$.
[5] All are ASUS P2B-DS, but I'll probably switch over to
Abit P6B duals next time.
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