Task priority choice and periodicity

Hi there,

I wonder how to choose the scheduling priority of my homemade tasks ? Is there a brief of all exisiting task and priority to see how can I adjust mine ?
And also how can I managed the periodicity of the scheduling process of my deamon task ?

By default the dev guide is at SCHED_PRIORITY_DEFAULT + 40. But I don’t know where it stand compare to other deamon. And there is no information about the scheduled periodicity.