Performance analysis of tasks synchronization for real time operating systems

Real time operating systems (RTOS) have a growing importance in the development of embedded projects based on microcontrollers (MCUs). They allow the development of multitasking applications providing deterministic behavior and basic services for inter-task communication. When it is selected an RTOS, it must take into account several criteria such as: license costs, memory footprint, predictability, and latency in handling of the critical operations triggered by internal or external events. This latency can also be influenced by the time required for task context switching operation. In this paper, we compare the time for task context switching in the case of four RTOSs used on ARM Cortex™-M based microcontrollers: FreeRTOS, uC-OS/II, Keil RTX, and RT-Thread. For these RTOSs, the time for task context switching is measured if synchronization is performed through events, semaphores and mailboxes. The tests are performed on ARM Cortex™-M4 and ARM Cortex™-M0+ based MCUs.