Multiprocessing? (Was: [MacPerl] acgi vs cgi (fwd))

[Howard Soroka <howards@netcom.com>]

>Ummmmmmmm.....no.  Multiprocessing does not equal multiple
>processors.  Multiprocessing means Multiple Processes.  The
>Mac kind-of does multiprocessing.  You can check this out
>by first bringing up BBEdit, MacPerl, QPQ, and Netscape.
>Check under the "?" area.  You will see all of these things
>are running on the system.  They are (if you want to
>stretch the actual means of the word) multiprocessing.  In
>my humble opinion though - what they are actually doing is
>a form of timesharing.  But others will probably disagree.
>

Sure enough, I diasagree. Back when I was in Famous Programmer's School in the early cretaceous period ('81, '82-ish) we believed these terms went with these (highly informal) definitions:

Multiprocessing: Use of more than one CPU (not possible with ONE CPU), presumably for some noble computational purpose (as opposed to say, paperweights).

Multitasking: More than one process running on a given single CPU. This is also known as Time-Sharing no matter how you slice it. You can't multitask on a single CPU without sharing time, unless you're in some other universe where guys like Newton and Einstein are considered idiots.

Parallel processing: something cool you could do if you had more than one processor and the ability to split up pieces of a program so that those multiple processors each ran a chunk of the program (thread) simultaneously, in the interest of getting better overall performance of the WHOLE program. Analogous to having nine women be pregnant for one month and getting a baby as a result, instead of one woman pregnant for nine months and getting the same result. Except that it's do-able.

Since I'm mostly lurking here, and reserve the right to be stupid, I invite others to tell me that my CS education is obsolete and everything I've said is wrong. It's important to me that I know whether or not my memory is working.

Cheers,

Howard



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