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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Timing Block of GNAT code in milliseconds
Date: 28 Apr 2005 21:26:00 +0100
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> I presume Real_Time uses Windows' performance counter which never
> jumps.  But I have no idea how Calendar behaves, especially in
> presence of some external time synchronization software like NTP.
> 
> Alas, both clock models are quite useless in a distributed
> environment.

I think that's going a bit far -- it has to depend what your
requirements are!

We are running on plain VxWorks and need millisecond sync over our
local network. If GNAT separated Real_Time from Calendar we could
probably have used Calendar; as it is we have our own similar package
which manages an offset from Calendar.

Any requirement much finer than millisecond sync is going to need
something more appropriate than plain old ethernet with a plain old
network stack (which takes about 150 us to traverse on this hardware
in the best of conditions!)

-- 
Simon Wright                               100% Ada, no bugs.