Re: Help clear up a misconception about SMP systems

Mike A. Harris (mharris@ican.net)
Sat, 10 Oct 1998 02:00:55 -0400 (EDT)

On Fri, 9 Oct 1998, Alex Buell wrote:

>Can you help clear up a misconception about SMP that I have at the
>moment?
>
>When two or more processors come into play, what is the increase rate of
>processing over a single processor? Is does it works out as 100% increase
>over that of a single processor or is it limited by other factors such as
>caching, disk i/o or whatever?
>
>I'm guessing it's a 100% increase.

No. I don't have an SMP system, nor have I used one, but I know
a bit about them.

For one, any programs you have, unless multithreaded will sit on
one CPU or the other. So if you boot up, and run program "Foo",
unless foo is multithreaded, it will run the same as on UP
system, perhaps even a bit slower. If you have a bunch of
processes running, however, each individual process will run no
faster than on a single CPU system, but you can run more
processes now. Multithreaded applications can take full power of
the multi CPU though, since different threads can operating on
different CPU's.

That is my (possibly incorrect) understanding anyways.

--
Mike A. Harris  -  Computer Consultant  -  Linux advocate


Linux software galore:  http://freshmeat.net




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