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From: BrianG <briang000@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada.Execution_Time
Date: Thu, 30 Dec 2010 19:40:08 -0500
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Date: 2010-12-30T19:40:08-05:00
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Dmitry A. Kazakov wrote:
> On Tue, 28 Dec 2010 14:14:57 +0000, Simon Wright wrote:
> 
>> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>>
>>> And conversely, the catastrophic accuracy of the VxWorks real-time
>>> clock service does not hinder its usability for real-time application.
>> Catastrophic?
>>
...
> 
> Yes, this thing. In our case it was Pentium VxWorks 6.x. (The PPC we used
> prior to it had poor performance) The problem was that Ada.Real_Time.Clock
> had the accuracy of the clock interrupts, i.e. 1ms, which is by all
> accounts catastrophic for a 1.7GHz processor. You can switch some tasks
> forth and back between two clock changes.
>  

So, we're talking about GNAT's use of VxWorks' features as
"catastrophic"?  That's not how I read the original statement.

(We use GNAT on VxWorks, but since we don't (yet) really use tasks, and 
have our own "delay" equivalent to match external hardware, I don't see 
its performance - but since I'm used to GNAT on DOS/Windows, I don't 
have very high expectations.  It sounds like I should keep that opinion.)

--BrianG