Software vs Hardware Implementations for Real-Time Operating Systems

In the development of the embedded systems a very important role is played by the real-time operating system (RTOS). They provide basic services for multitasking on small microcontrollers and the support to implement the deadlines imposed by critical systems. The RTOS used can have important consequences in the performance of the embedded system. In order to eliminate the overhead generated by RTOS, the RTOS primitives have begun to be implemented in hardware. Such a solution is the nMPRA architecture (Multi Pipeline Register Architecture - n degree of multiplication) that implements in hardware of all primitives of an RTOS. This article makes a comparison between software RTOS and nMPRA systems in terms of response time to an external event. For comparison, we use three of the most commonly used RTOS in developing embedded systems: FreeRTOS, uC/OS-III and Keil RTX. These RTOSs are executed on a microcontroller that works at the same frequency as the implementations of the nMPRA architecture on a FPGA system.