From: mueller@informatik.hu-berlin.de (Frank Mueller)
Subject: Re: tasking in Ada and Annex D question
Date: 1999/02/03
Date: 1999-02-03T00:00:00+00:00 [thread overview]
Message-ID: <79925b$mo7$1@hahn.informatik.hu-berlin.de> (raw)
In-Reply-To: 798u7r$b2k$2@plug.news.pipex.net
OK, one more comment:
>So I believe that in Ada95, the
>concurrency of tasks is much more important than the performance
>of task switches, because tasks are not used that much any more
>for time-consuming synchronization (reader/writer buffer tasks,
>semaphore tasks, etc.).
Well, think again. If you have as many processors as tasks *and* you
use protected functions/procedures only *and* your system supports
multiprocessing (kernel threads), you may be right.
In most realistic case, and any time you use protected entries, you
wrong, IMHO. Your tasks will context switch upon synchronization.
And the context switching time will have an impact on the performance.
For more details, read our SigAda'98 paper:
"The Rendezvous is Dead -- Long Live the Protected Object" by D. Macos and F.
Mueller in ACM SIGAda'98, Nov 1998, pages 287-293,38
available as postscript on
http://www.informatik.hu-berlin.de/~mueller/publications.html
The punch line: The rendezvous may not be completely dead but protected objects
are preferable where they can be used (and the paper says exactly where).
--
Frank Mueller E-Mail: mueller@informatik.hu-berlin.de WWW: http://www.informatik.hu-berlin.de/~mueller
next prev parent reply other threads:[~1999-02-03 0:00 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-01-31 0:00 tasking in Ada and Annex D question nabbasi
1999-02-01 0:00 ` Dr. Hubert B. Keller
1999-02-02 0:00 ` Markus Kuhn
1999-02-02 0:00 ` robert_dewar
1999-02-02 0:00 ` Markus Kuhn
1999-02-02 0:00 ` Niklas Holsti
1999-02-03 0:00 ` Ehud Lamm
1999-02-03 0:00 ` robert_dewar
1999-02-02 0:00 ` robert_dewar
1999-02-02 0:00 ` Roger Racine
1999-02-02 0:00 ` robert_dewar
1999-02-03 0:00 ` Nick Roberts
1999-02-03 0:00 ` Frank Mueller [this message]
1999-02-03 0:00 ` Frank Mueller
1999-02-03 0:00 ` Roger Racine
1999-02-03 0:00 ` Tom Moran
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