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Date:      Fri, 22 Jan 1999 23:15:10 -0500 (EST)
From:      "John S. Dyson" <dyson@iquest.net>
To:        rcarter@pinyon.org (Russell L. Carter)
Cc:        dyson@iquest.net, dufault@hda.com, dillon@apollo.backplane.com, hackers@FreeBSD.ORG
Subject:   Re: Error in vm_fault change
Message-ID:  <199901230415.XAA62055@y.dyson.net>
In-Reply-To: <199901230331.UAA18297@psf.Pinyon.ORG> from "Russell L. Carter" at "Jan 22, 99 08:31:38 pm"

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Russell L. Carter said:
> %> 
> %Your comments about "goals" are correct.  The obsolete notion of priority
> %is specious.
> 
> No, it isn't.
> 
> People (or rather organizations) are now using "OSS unix" stuff to
> do things like control flight and targeting and other interesting
> stuff.  The lingo is based on "priority".   Who gives a shit
> about interactive users ;-).  Meeting deadlines is probably
> orthogonal to system throughput.
> 
Deadlines are a major parameter.  Even responsiveness to users
is a form of deadline.  Priority is only a short term scheduling
hint, and doesn't really describe the resource requirements.  Priority
is a snapshot of what needs to run at an instant in time.  Priority
as a time invariant scalar (or even as the unix style slowly changing
priority) isn't flexible enough anymore.  Since we are talking here
about resource mgmt, constraining ourselves to thinking about "priority"
is just too inflexible.

When looking into alternative scheduling mechanisms, priority
just doesn't describe an adequate solution to the new range
of problems (multimedia scheduling, realtime data, timesharing),
that need to be solved concurrently (perhaps with the same
resources.)

-- 
John                  | Never try to teach a pig to sing,
dyson@iquest.net      | it makes one look stupid
jdyson@nc.com         | and it irritates the pig.

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