FW: RTEMS time overflow problem

[Nasim Zehra]

________________________________________
From: Nasim Zehra
Sent: Monday, June 29, 2009 8:17 PM
To: Thomas Dörfler
Subject: RE: RTEMS time overflow problem

thomas
   yes i did .The mode of the tasks are preemptable and also i know that priorities  does not change in rate monotonic and i applied different priority to different task according to their execution time which was the criteria of rate monotonic.

regards
---
nasim zahra
________________________________________
From: Thomas Dörfler [Thomas.Doerfler at embedded-brains.de]
Sent: Monday, June 29, 2009 6:32 PM
To: Nasim Zehra
Cc: rtems-users at rtems.org
Subject: Re: RTEMS time overflow problem

Masim,

unfortunately you did not mention how you created the tasks. did you
apply the scheduling priorities properly (Note: The rate monotonic
manager does NOT change task priorities. In just makes the tasks "ready"
at the proper time.).

Did you make the tasks preemptable?

wkr,
Thomas.

Nasim Zehra wrote:
> dear users
>    also tell me that if i select periods of tasks such that when they are executed ,they are in running condition and before they are deleted ,time over flow error is occurred.Is there any solution for that.
> i am having four tasks
> 1st--------executed in 2202 ticks
> 2nd-------// //            848
> 3rd-----------------------246
> 4th--------------------88
>  above mentioned ticks are equal to execution time of respective tasks.
> now i am selecting periods for them randomly so that upper bound condition for 4 tasks should be met according to rule of rate monotonic schedualing.like that
>  1st---------8000 period in terms of ticks
> 2nd---------3000
> 3rd---------2000
> 4th---------5000
>
> using these periods my U = 69.85%
> while theoritical U= 4(2(1/4) - 1)= 75.682%
>  so 69 %<75%
> => tasks are scheduable.
> but implementing it causes ime oveflow error on T simulator for leon3 processor.
>
> kindly help out.
>
> regards
> --------
> nasim
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> rtems-users at rtems.org
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