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From: slos <new.stephane.los@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada and linux real time
Date: Wed, 7 Mar 2012 04:10:14 -0800 (PST)
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Date: 2012-03-07T04:10:14-08:00
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On 7 mar, 09:23, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:
> On Tue, 6 Mar 2012 13:19:24 -0800 (PST), slos wrote:
> > I have tried some code on both RT and non RT kernels but was not
> > impressed by the difference.
>
> What kind of difference you expected to see?
>
> --
> Regards,
> Dmitry A. Kazakovhttp://www.dmitry-kazakov.de

I can't post the code from the place I am, so I will just describe it.

My little test schedules a periodic task with a period of let's say
10ms.

The periodic task then calls the Ada.Real_Time.Clock and measures the
difference to the scheduled time.
The difference is stored in an array of durations where each index
correspond to an interval.
Difference < 0.1 * period
Difference < 0.2 * period
Difference < 0.5 * period
Difference < 1.0 * period
etc...
The purpose is to characterise the scheduling.
Running the program for a while I get an image of how it behaves.
Using both RT and non RT kernels give about same finding.
Thousands are correct while some are clearly out of specified period.
And I have not put any load on the system yet.

I plan to use tools provided by OSADL to stress the system but of
course it means nothing if I need some real time Ada runtime to
achieve real time performance and can't get it for free.

BR
St=E9phane