Thread Scheduling question


Raj Gundi
 

Hi,

 

This is a question related to thread scheduling. Imagine you have 2 custom threads in addition to the “main thread”. The custom threads are created static (K_THREAD_DEFINE) and are cooperative threads (let’s say the priority is -5) whereas the main thread is preemptive (priority 0). Now, as soon as the main thread is handed control (via switch_to_main_thread), it is possible the scheduler gets triggered and one of the cooperative threads gets scheduled. This may be undesirable since main thread may need to get some stuff done before the cooperative threads take over.

 

Is my reading of the above situation correct? If yes, I would like to see how this can be mitigated. One easy thing is to make main thread also cooperative (say, a priority of -6). The other is to lock the scheduler as soon as the main thread is entered and unlock only after the relevant stuff is addressed. Please let me know your views.

 

Regards,

Raj

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