Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!decwrl!ucbvax!VENUS.YCC.YALE.EDU!WHITCOMB%KOBOT
From: WHITCOMB%KOBOT@VENUS.YCC.YALE.EDU ("whitcomb%kobot.decnet@venus.ycc.yale.edu")
Newsgroups: comp.sys.transputer
Subject: Re: Transputer Scheduler.
Message-ID: <8903312242.AA06901@tcgould.TN.CORNELL.EDU>
Date: 31 Mar 89 22:48:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 49

Greetings:

  The T-800 support for scheduling and concurrency is described succinctly 
on pages 52-53 of the first listed reference.

  The essential facts are the following:

  (1) High priority processes run until they either terminate or block 
      themselves.  First come, first serve.  High priority processes
      are *not* timesliced.

  (2) Low priority processes run only when no high priority processes are
      available to run.

  (3) Low priority process run until they terminate, block themselves, or 
      until they have run for one to two *timeslice periods*.   
    
  (4) A *timeslice period* is 5120 cycles of the external clock.  This is
      about one mS at 5MHz.
  
  (5) Given n low priority processes, the maximum time a process will wait
      on the process queue for cpu time is 2n-2 timeslice periods.

  The manual gives a complete account, defining which actions will cause a 
process to block, exactly how the queues are handled, and the like.

  You note seems to suggest that there is a lack of documentation on this
topic.  This is not so.  If one wants understand how the machine works, 
and how the INMOS implementation of OCCAM is constructed, you absolutely 
must have the following references:

  Transputer Reference Manual
  ISBN 0-13-929001-X

  Transputer Technical Notes
  ISBN 0-13-929126-1

  Communicating Process Architecture
  ISBN0-13-629320-4

  Transputer Instruction Set
  ISBN 0-13-929100-8


  It is all there.  In excrucuating detail.

                The Best,

                    -Louis Whitcomb