IAR PowerPac RTOS User Guide

Performance and resource usageThis chapter covers the performance and resource usage of embOS. It explains how to benchmark IAR PowerPacRTOS and information about the memory requirements in typical systems which can be used to obtain sufficientestimates for most target systems.IntroductionHigh performance combined with low resource usage has always been a major design consideration. IAR PowerPacRTOS runs on 8/16/32-bit CPUs. Depending on which features are being used, even single-chip systems with less than2 Kbytes ROM and 1 Kbyte RAM can be supported by IAR PowerPac RTOS. The actual performance and resourceusage depends on many factors (CPU, compiler, memory model, optimization, configuration, etc.).Memory requirementsThe memory requirements of IAR PowerPac RTOS (RAM and ROM) differ depending on the used features of thelibrary. The following table shows the memory requirements for the different modules.Module Memory type Memory requirementsIAR PowerPac RTOS kernel ROM 1100 - 1600 bytes *IAR PowerPac RTOS kernel RAM 18 - 25 bytes *Mailbox RAM 9 - 15 bytes *Binary and counting semaphores RAM 3 bytesRecource semaphore RAM 4 - 5 bytes *Timer RAM 9 - 11 bytes *Event RAM 0 bytesTable 129: IAR PowerPac RTOS memory requirements* Depends on CPU, compiler, and library model usedBenchmarkingIAR PowerPac RTOS is designed to perform fast context switches. This section describes two different methods tocalculate the execution time of a context switch from a task with lower priority to a task with a higher priority.The first method uses port pins and requires an oscilloscope. The second method uses the high-resolution measurementfunctions. Example programs for both methods are supplied in the \Example directory of your IAR PowerPac RTOSshipment.Segger uses these programs to benchmark the IAR PowerPac RTOS performance. You can use these examples toevaluate the benchmark results. Note, that the actual performance depends on many factors (CPU, clock speed,toolchain, memory model, optimization, configuration, etc.).PPRTOS-2 127