Path: utzoo!utgpu!water!watmath!clyde!rutgers!mcnc!rti!sas!jcz
From: jcz@sas.UUCP (John Carl Zeigler)
Newsgroups: comp.arch
Subject: Re: Single tasking the wave of the future?
Summary: Multi - tasking . . .
Message-ID: <310@sas.UUCP>
Date: 10 Dec 87 03:39:30 GMT
References: <201@PT.CS.CMU.EDU> <388@sdcjove.CAM.UNISYS.COM> <988@edge.UUCP> <151@sdeggo.UUCP>
Organization: SAS Institute Inc.,Cary NC,25712
Lines: 38


It might be informative to remember why multi-tasking was invented
in the first place.   Back in the 60's Mr Warbucks wandered down to the
Data Processing Department to see what kind of trouble that particular
budgetary sink-hole was getting into.    He wandered into the Computer
Room and spied a Computer Programmer with a couple cases of cards
turning dials and flipling switches.   "Hi, what are you doing," he asked.
   "Oh, Hello Mr. Warbucks.  I am testing our new Social Security Accounting
and Collating System.   Here, watch this."
   With that he flipped one of the switches and a machine began spewing
cards into a box.   After a few hundred cards had dropped, one popped out
into a slot.  "See, here is your card," explained the Programmer.
   "That's nice, but what does that light mean?" he said,
pointing to a warm red light on the front panel.
   "That's the WAIT light,  It goes on whenever the CPU is idle."
   "But, it NEVER went off!"
   "Right!  I have made this program so fast that the light doesn't have
time to stop glowing enough for you to see it."
   "You mean for most of the time the machine wasn't doing anything!"
   "Well, that is one way to look at it."
   "Why couldn't it have been doing something else????   I am not going
pay a hundred times your salary a year just to have the damn thing
WAITing!!!!   Get that fixed!"

Seriously.   I do not mind having my computer doing something else
while I am thinking, or while the disk drive is thinking, either.
Most applications are NOT CPU bound.  Most are I/O bound.  The overhead
of task switching will always be paid for by the increased utility of
the machine.  (not forgetting that L = yW, (y is upside down))
Until we get a better architectural paradigm than the current
'Von Neuman Bottle-Neck', that is.    Any discussion on that??


-- 
--jcz
John Carl Zeigler
SAS Institute Inc.
Cary, NC  27511           (919) 467-8000        ...!mcnc!rti!sas!jcz