From: stt@houdini.camb.inmet.com (Tucker Taft)
Subject: Re: Looking for implementation idea
Date: 1999/02/07
Date: 1999-02-07T00:00:00+00:00 [thread overview]
Message-ID: <F6suus.n1x.0.-s@inmet.camb.inmet.com> (raw)
In-Reply-To: m2yamagkdi.fsf@wf-rch.cirr.com
Corey Minyard (minyard@acm.org) wrote:
: ...
: One question for the Ada experts: Ada protected types don't work in
: SMP since they are task priority based, do they?
Ada protected types *do* work on a multi-processor.
They boost the priority to prevent unbounded priority inversion, not to lock.
On a mono-processor, it turns out that boosting the priority
is sufficient to accomplish mutual exclusion. On a multiprocessor,
the protected type will also need to acquire a (probably spin) lock.
: ... Or maybe I'm missing
: something. If they don't, maybe we should think about adding a real
: semaphore to the Ada spec.
No need. Protected types do the job, in a way that is independent
of the number of physical processors.
I'm curious -- where did you get the impression that protected
types did not work on a multiprocessor? I'm wondering how common
is this misconception...
: --
: Corey Minyard Internet: minyard@acm.org
: Work: minyard@nortelnetworks.com UUCP: minyard@wf-rch.cirr.com
-Tuck
--
-Tucker Taft stt@averstar.com http://www.averstar.com/~stt/
Technical Director, Distributed IT Solutions (www.averstar.com/tools)
AverStar (formerly Intermetrics, Inc.) Burlington, MA USA
next prev parent reply other threads:[~1999-02-07 0:00 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-02-07 0:00 Looking for implementation idea Thomas Handler
1999-02-07 0:00 ` Paul Duquennoy
1999-02-08 0:00 ` Thomas Handler
1999-02-07 0:00 ` Corey Minyard
1999-02-07 0:00 ` Tucker Taft [this message]
1999-02-07 0:00 ` Corey Minyard
1999-02-08 0:00 ` Tucker Taft
1999-02-07 0:00 ` Corey Minyard
1999-02-08 0:00 ` robert_dewar
1999-02-08 0:00 ` dennison
1999-02-08 0:00 ` robert_dewar
1999-02-08 0:00 ` Tucker Taft
1999-02-09 0:00 ` robert_dewar
1999-02-11 0:00 ` Ehud Lamm
1999-02-07 0:00 ` Larry Kilgallen
1999-02-08 0:00 ` dewar
1999-02-08 0:00 ` dennison
1999-02-08 0:00 ` robert_dewar
1999-02-07 0:00 ` Tom Moran
1999-02-07 0:00 ` Corey Minyard
1999-02-08 0:00 ` Thomas Handler
1999-02-07 0:00 ` Niklas Holsti
1999-02-08 0:00 ` Thomas Handler
1999-02-09 0:00 ` Niklas Holsti
1999-02-10 0:00 ` Thomas Handler
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