The performance parameters of RTOSs are the most vital considerations for a system developer as they determine the performance of the entire system. The paper first discusses a fundamental overview of the most important of these parameters and how they affect system performance. It is observed that scheduling is the most vital parameter. Further, the paper provides an intuitive description of three famous Open-Source RTOSs-RT Linux, FreeRTOS and eCos-based on the parameters, kernel architecture and applications. Effort is made to include details which will simplify the task of a developer who wishes to use these RTOSs. Finally, the paper provides simple and universally implementable benchmarking methods for measurement of parameters for any RTOS. It is our effort to organize the complex and often contradictory information about RTOSs and present it in a manner through which the decision-making process is simplified.

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