Scheduling Polices and soft realtime doubts in RTAI/Fusion

Paolo Mantegazza mantegazza at aero.polimi.it
Mon Jul 11 21:04:53 CEST 2005


Rodrigo Rosenfeld Rosas wrote:
> First of all, thank you a lot for your reply. There are still some minor 
> doubts that I hope you'll be able to elucidate me.
> 
> When the tasks have the same priority how can I know if the policy will 
> be FIFO or RR? And how can I choose which of them to use?
> 
> When you say:
> [RMS can easily be mapped on prio-based scheduling schemes.]
> 
> You mean that I should change the code to add RMS or just to define 
> previously the task priorities accordling to their periods? I think you 
> meant the last one ("prio-based"), right?
> 

In RTAI call "rt_spv_RMS", whenever needed, and your periodic tasks 
should be scheduled according to RMS policy automatically.

> [EDF requires a bit more work when doing this without some native 
> support of the scheduler as it is the case with fusion.]
> 
> Sorry, my English is not that good. Did you want to mean that fusion has 
> native support or not? Which is the case in fusion? And if it has 
> support, how can I enable it?
> 

Instead of callin rt_task_wait_period call rt_task_set_resume_end_times, 
see "/showroom/v3.x/kern/edf". Notice that all edf tasks automatically 
assume a priority greater than any existing task.


PAolo.





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