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Date: Fri, 18 Dec 1998 16:03:38 +0000
From: Karl Pielorz <kpielorz@tdx.co.uk>
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To: =?iso-8859-1?Q?Jos=E9=20M=AA?= Alcaide <jose@we.lc.ehu.es>
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Subject: Re: SMP benchmarks
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"José Mª Alcaide" wrote:
 
> After reading a recent message from Jordan (I lost its reference)
> about the "makeworldbench" test results, I was a bit worried: is one
> of the two CPUs of my new computer being wasted by the FreeBSD
> kernel? Uh-oh! Then I did a little test running one of the BYTE
> benchmarks (arithoh). I did three runs with one, two and three
> simultaneous processes. These are the results:
>
> [snip]
>
> In summary, at least making pure arithmetic computing, SMP does
> its work.

Yes, this is what I was saying to Jordan - as the FreeBSD kernel currently has
a 'big lock' around it, meaning on an SMP machine AFAIK only one CPU can be
'in the kernel' at a time, if the other tries - it will get blocked (and
probably go carry on with something else?)

SMP is still a winner on FreeBSD though - because of Unix's nature to be very
'multi-processed', i.e. when you run Apache you don't just run 1 instance of
apache, you run 4 or 5 (or more as the load increases) - so you get to the
advantages of more CPU's - up until the system gets kernel bound (or IO
bound)...

This is what your test results proved... :)

So, if you have something like rc5des - your better off running 2 copies of it
on an SMP system... ;-)

-Kp

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