Major concerns regarding any RTOS selection

Question

Describe major concerns regarding any RTOS selection?

Answer 1

Interrupt Latency means the time taken through the processor to pass the control to ISR after the interrupt is build. Surely this is the hardware feature. Footprint of the OS matters since with the similar compiler and similar optimization techniques, Different OS's will have distinct footprint. Therefore it is can be looked upon while selecting the RTOS. RTOS can be selected looking at several API support it provides. Synchronization support,  Scheduler algos, & memory management of the OS.