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From: steve@TITAN.TSD.ARLUT.UTEXAS.EDU (Steve Glicker)
Newsgroups: comp.lang.ada
Subject: Task/Process switch times
Message-ID: <8911221603.AA18220@titan.tsd.arlut.utexas.edu.tsd.arlut.utexas.edu>
Date: 22 Nov 89 16:03:34 GMT
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Over the last few months, I have been collecting numbers on
task/process switching speeds.  Several tests have been run were two
tasks or processes invoke each other several hundred thousand times,
execution time is then divided by switches...

The information I have collected is in the following table.  These
test have been conducted on an informal bases.  Does anyone have
estimates on the speed of lightweight UNIX processes, embedded systems
numbers, etc.?  I would also appreciate any references to work
published on this topic.

 Platform        Test             Switching Speed
==============  ================ =================

microVAX (VMS)  VMS processes    ~ 0.6  ms

microVAX (VMS)  DEC Ada tasks    ~ 0.6  ms

Sun 3/50 (UNIX) Function call    ~ 0.01 ms

Sun 3/50 (UNIX) Simula processes ~ 0.2  ms

Sun 3/50 (UNIX) Verdix Ada tasks ~ 0.3  ms

Sun 3/50 (UNIX) UNIX/C processes ~10.0  ms


I understand that the microVAXs ran at ~0.9 VAX 780 MIPS and the Sun
3/50 at ~1.5 VAX 780 MIPS.  In the cases of Ada and Simula a scheduler
supplied with the language was used.

Steve Glicker
(steve@titan.tsd.arlut.utexas.edu)