A thread's priority can vary during its execution, either from direct manipulation by the thread itself or from the kernel adjusting the thread's priority as it receives a message from a higher-priority thread.
In addition to priority, you can also select the scheduling algorithm that the kernel will use for the thread. Although our libraries provide a number of different ways to get and set the scheduling parameters, your best choices are pthread_getschedparam(), pthread_setschedparam(), and pthread_setschedprio(). For information about the other choices, see “Scheduling policies” in the Programming Overview chapter of the QNX Neutrino Programmer's Guide.