Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!munnari.oz.au!csc.anu.edu.au!manuel!ccadfa!prolix!dac
From: dac@prolix.ccadfa.oz.au (Andrew Clayton)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: Single user OS schedulers (Was Re: How do we change the scheduler?)
Message-ID: <189704d7.ARN27ab@prolix.ccadfa.oz.au>
Date: 27 Jan 91 11:19:19 GMT
References: <1991Jan23.213736.28220@Neon.Stanford.EDU> 
 <1991Jan24.152931.1325@NCoast.ORG><1991Jan25.073516.29644@Neon.Stanford.EDU> 
 <1991Jan26.035750.11786@NCoast.ORG><1991Jan27.014242.2863@Neon.Stanford.EDU>
Reply-To: ccadfa.cc.adfa.oz.au!prolix!dac@munnari.OZ.AU
Followup-To: comp.sys.amiga.advocacy
Organization: I'm not an Organization - I'm a person!
Lines: 44

In article <1991Jan27.014242.2863@Neon.Stanford.EDU>, Evan J Torrie writes:

>   But it IS the OS's [duty|right|job] to be as transparent to the user
> as possible.  If the OS causes my interaction with the computer to be
> difficult (because of slow response), then it's interfering with what
> I want to do (remember, this is restricted to a single user system)  

Huh?  The OS doesn't interfere with your DECISION to run multiple programs at
the same time.  By default, spawned programs have a priority of zero (0) thus
they *share equitably* the CPU resource.

>   Perhaps we should take a vote:
> 
>   How many of you would prefer the application you're interacting with
> in the foreground to be jerky, in return for your background ray
> tracer or compile getting a few extra timeslices?
>   How many would prefer the application to be smoother, in return for
> stealing some timeslices from your background tasks?

Duh!  Lets make the OS democratic!  :-).  *YOU*, all by your lonesome, get to
make the decision if you want processes to have priority.  Most people don't
mess with the scheduler.  It's best left alone.

>   Even if I run a raytracer at priority -1, and then another compute
> bound task, (say calculating Pi at priority 0), then the raytracer
> will starve...  To a person coming from a Unix background, this is not
> attractive (in fact, one might be tempted to not even call it "true"
> multitasking [ducking for cover :-)]).

So, Evan, why do you mess with priority in the first place?  Leave the tasks
at the default (zero) priority, and they will peacefully coexist and SHARE the
resource.  If you want to do something that is input sensitive, (like edit a
file), then CHANGE the priority of the CPU hog program to -1.  A shift of 1
either up or down in priority has a HUGE effect on the other tasks.

In other words, if it ain't broke, don't fuck with it.

> Evan Torrie.  Stanford University, Class of 199?       torrie@cs.stanford.edu   

Dac
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 _l _  _   // Andrew Clayton. Canberra, Australia.         I Post  .
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