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From: hmm@julien.informatik.uni-dortmund.de (Hans Martin Mosner)
Newsgroups: comp.lang.smalltalk
Subject: Re: anyone using time-sliced scheduling w/st80?
Message-ID: <3117@laura.UUCP>
Date: 22 Mar 91 13:07:47 GMT
References: <HUGGINS.91Mar12085614@dino.ti.com>
Sender: news@laura.UUCP
Reply-To: hmm@julien.informatik.uni-dortmund.de (Hans Martin Mosner)
Organization: georg Heeg Objektorientierte SystemTechnologien (HOST)
Lines: 15

For a customer project, we have implemented more priority levels and
timeslicing in PPS Smalltalk-80 release 2.3 and 2.5.  For the user
interface code and other things to keep working, the priority levels
UserSchedulingPriority and above must not be timesliced.  So we lifted
them and introduced a number of background priorities in addition to
UserBackgroundPriority.  Processes at these priority are regularly put
at the end of their respective scheduling queues by a high-priority
process (I think we currently have slices of 200 msecs or so).  Doing
the priority level extension is a bit tricky, but the timeslicing in
itself is very straightforward.
Of course you need something like the "Good Citizenry" code by PPS
so that the background processes can run at all, but we had that in
the images anyway.

Hans-Martin