Re: insmod priority

> Dear list,
> I am wondering what happens when running more than one real-time 
> Application on an RTLinux System. The second module is loaded by 
> executing the insmod command. Does the insmod process have a lower 
> priority than the already running real-time threads, or will it preempt 
> them? This might especially be a problem when the init_module function 
> needs much processing power.

INsmod is called in non-RT (Linux) context and has lower priority than
any running RT-task. so if you want to startup a set of rt-tasks in a
synced way you need to initialize them and then let them all wait 
(i.e. pthread_barier) bofore starting up processing

> Another thing I am not sure about are the fifo handlers. Is the handler 
> called when all real-time threads are idle, or will it preempt them?

a fifo handler will be called when a write to the fifo is done from user-space
- this write can't happen if the rt-system is active so the handler can't
be called unless the rt-system is inactive. a RT-thread will preempt a fifo
handler that was triggert from user-space. With the fifos rt-handler it 
depends on who calles the write - the fifos rt-handler will be executed in 
the context of the calling process so it can be preempted by higher priority
processes (if interrupted outside of the spinn-lock protected code sequence)

hofrat
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