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From: ForthNet@willett.pgh.pa.us (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: Multi-tasking and Multi-user
Message-ID: <2887.UUL1.3#5129@willett.pgh.pa.us>
Date: 16 Jun 91 13:07:46 GMT
Organization: (n.) to be organized.  But that's not important right now.
Lines: 40


 Date: 06-14-91 (21:41)              Number: 162 of 162 (Echo)
   To: ELLIOTT CHAPIN                Refer#: 150
 From: JACK WOEHR                      Read: NO
 Subj: MULTI-TASKING AND MULTI-U     Status: PUBLIC MESSAGE
 Conf: FORTH (58)                 Read Type: GENERAL (+)

 -> Nothing specific; but I suppose it came to me in part because of Brad
 -> Rodriguez' article "Multiprocessor Forth Kernel" in
 -> Forth Dimensions vol. XI, #3.


         Anyway, for a small number of tasks, a prioritized round robin
 is just as effective as a prioritized queue. It's when you have a large
 number of tasks, as in a multiuser system (UNIX) or in a process control
 system (EMCS/Express from FInc) wherein you have to assure that certain
 critical tasks execute ahead of others, and complete their work before a
 lower priority task gets its first whack at processing, that queueing
 becomes important.

         There is no reason Forth couldn't task in any of these other
 ways, it's just tradition and the influence of the low overhead and
 deterministic behaviour of round-robin tasking that has influenced the
 Forth taskers you find in most systems.

         As to Determinism ... a recent program I wrote was so
 deterministic in its task ( four tasks) overhead that I was able to
 write music for one task that plays in rythm without any special tricks,
 just the very predictable time slice that the traditional round robin
 gives to it.

                 =jax=

 NET/Mail : RCFB Golden, CO (303) 278-0364 VESTA & Denver FIG for Forth!
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