From: jgrimm@TorreyPinesCA.ncr.com (Jeffrey Grimmett 9999)
Subject: Re: Oh my God! Help my friend not buy an IBM!
Organization: NCR (Torrey Pines Development Center)
Disclaimer: This posting does not necessarily reflect the opinions of NCR.
Date: Fri, 20 Nov 92 17:25:23 GMT

Quoth dnavas@oracle.uucp (David Navas):

]> Let's take this example, shall we?
]> Ray Tracer in background, Editor in foreground:
]> 
]> Amiga:
]>     Ray Tracer and Editor get round-robin scheduled so Editor will get no more
]>     than 50% of the CPU.  If these are the only two tasks, it will also get
]>     no less than about 50% of the CPU....

Whooooooooooooaaaaa!  Slow down, sparky, before you start this experiment you
best get a bit more information.

In the case you describe above, the time allocation will not be 50-50 UNLESS
both programs are requiring CPU time constantly AND if they both happen to be
at the same priority.

Most ray tracers I've come across are smart enough to assign a lower pri to
the actual trace engine, so that other tasks can interrupt as needed.

Now, in the case you're describing above (one that I am very familiar with,
BTW), assume both have the same pri for a minute... even at that, I bet you
find the ray tracer getting more than 50% during normal editor operation, as
most people can't type so fast as to require half the clock cycles of a 7MHZ
chip, much less an 020+ !  In some cases, yep, there will be CPU-intensive
operations from the text processor, such as search-and-replace in a 1 meg
text file or something similar.  However, the ray tracer, while tracing rays,
is running more or less constantly so it'll take all the CPU time it can get.

BTW, even if the ray tracer is higher pri than the editor, chances are you
won't be locked out as the input handlers, drivers, workbench, etc etc
generally operate at a very hi priority as compared with most tasks.  Wouldn't
make sense to lock out the keyboard, eh?  :-)

]> OS/2:
]>     Editor gets as much CPU as it needs.
]>     Ray Tracer gets the rest.  Exactly like Amiga case 2:

Actually, just like the Amiga PERIOD.  Where's this 50/50 fantasy coming
from, anyway?

]> Would someone please tell me, besides the fact that OS/2 has a better -default-
]> option for handling bg/fg processes, what the devil the difference is here?

Well, aside from the fact that you were wrong to begin with, see my other posts
on OS/2.  personally I feel it's the only real option for beemers, but then
I don't plan on beeming any time soon.

]> Again, I am assuming (stupid me) that OS/2 2.0's priority classing and
]> scheduling have remain unchanged from 1.3.  They may, indeed, have changed,
]> but I do not know exactly how.

Don't worry about the OS/2 side, you still need work on the Amiga side....

-- 
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Jeff Grimmett [SuperBitMap BBS]          * fido!1:202/1401.0 [619-460-7290]
jeff_grimmett@f1401.n202.z1.fidonet.org  * jgrimm@TorreyPinesCA.ncr.com
 The opinions expressed in this message are thoughtful, reasoned, and logical.
      	It goes without saying that they are not those of my employer.
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