Measuring Real-Time Performance Of An RTOS - Express Logic

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Preemptive Context Switching • Threads run until preempted by a higher priority thread. • This test consists of 5 threads that each have a unique priority. – All threads except the lowest priority thread are in a suspended state. – The lowest priority thread resumes the next highest priority thread. – That thread resumes the next highest priority thread and so on until the highest priority thread executes. – Each thread increments its run count and then suspends. – Once processing returns to the lowest priority thread, it increments its run counter and once again resumes the next highest priority thread - starting the whole process over again. Thread0 Count Suspend Loop Thread1 Count Resume Thread0 Suspend Loop Thread2 Count Resume Thread1 Suspend Loop Thread3 Count Resume Thread2 Suspend Loop Thread4 Count Resume Thread3 Loop 10
Interrupt Handling • Must consider two components • Interrupt Latency (“<strong>Time</strong> to ISR”) – How long are interrupts disabled? • Task Activation Overhead (“<strong>Time</strong> to Task”) – How quickly can a thread/task respond? • “Hurry Up and Wait” Can Be Misleading • Low interrupt latency, but delayed task activation – Can OS services be called from ISR? • “Split-Level” Interrupt Handling – Low level ISR responds to hardware – High Level ISR/Task calls OS services – Task performs processing 11
Page 1 and 2: Express Logic, Inc. © 2006, Expres
Page 3 and 4: Most Important RTOS Capabilities
Page 5 and 6: Thread-Metric: An Open RTOS Benchma
Page 7 and 8: How Are Services Measured? • Lots
Page 9: Cooperative Context Switching • T
Page 13 and 14: Message Processing • A Thread sen
Page 15 and 16: Memory Allocation • Applications
Page 17 and 18: Test Environment • ARM Versatile
Page 19 and 20: How To Get The Code • Download fr

Measuring Real-Time Performance Of An RTOS - Express Logic

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