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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Ada.Execution_Time
Newsgroups: comp.lang.ada
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Date: Tue, 28 Dec 2010 17:34:06 +0100
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Date: 2010-12-28T17:34:07+01:00
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On Tue, 28 Dec 2010 16:18:11 +0000, Simon Wright wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> 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.
> 
> Our experience was that where there are timing constraints to be met, or
> cyclic timing behaviours to implement, a milliscond is OK.
> 
> We did consider running the VxWorks tick at 100 us but this was quite
> unnecessary!

We actually have it set at 100 us, I believe.

But we need high accuracy clock not for switching tasks. It is for time
stamping and frequency measurements.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de