Dynamic memory (or run-time memory) usage is under direct control of the application. As a result, the static memory (or fixed memory) usage of ThreadX is determined by the development tools e.g., theĬompiler, linker, and locator. ThreadX resides along with the application program. Unlike ISRs, however, Application Timers cannot interrupt each other. Just like ISRs, Application Timers most often interrupt thread execution. Such timers are used byĪpplications to perform time-outs, periodics, and/or watchdog services. Types of Program Execution Application TimersĪpplication Timers are similar to ISRs, except the hardware implementation (usually a single periodic hardware interrupt is used) is hidden from the application. However, interrupts may also occur inside of an executing ISR or an Application Timer.įIGURE 2. In most cases, interrupts occur during thread execution (or in the thread scheduling loop). This predefined program area is commonly called an Interrupt Service Routine. On detection of an interrupt, the processor saves key information about the current program execution (usually on the stack), then transfers control to a predefined program area. Without interrupts it would be extremely difficult to respond to changes in the external world in a timely manner. Interrupts are the cornerstone of real-time systems. This process of continually executing and scheduling threads is the most common type of program execution in ThreadX applications. After the thread is finished (or another higher-priority thread becomes ready), execution transfers back to the thread scheduling loop to find the next highest priority ready thread. When a ready thread is found, ThreadX transfers control to it. The scheduling loop looks for an application thread ready for execution. Thread ExecutionĪfter initialization is complete, ThreadX enters its thread scheduling loop. Initialization includes all program execution between processor reset and the entry point of the thread scheduling loop.

InitializationĪs the name implies, this is the first type of program execution in a ThreadX application. More detailed information about each of these types is found in subsequent sections of this chapter. There are four types of program execution within a ThreadX application: Initialization, Thread Execution, Interrupt Service Routines (ISRs), and Application Timers.įigure 2 shows each different type of program execution. Each functional component is presented in an easy-to-understand manner. A simplified study of scheduler for real time and embedded system domain.This chapter contains a description of the high-performance Azure RTOS ThreadX kernel from a functional perspective. International Journal of Computer Science and Information Security, 2009, 6(2):61-66 Google Scholar A new scheduling algorithms for real time tasks. IEEE/ACM Transactions on Networking, 2003, 11(4):592-601 Google Scholar Digital Library Fair scheduling with tunable latency:A round-robin approach. Information Technology Journal, 2007, 6(2):288-293 Google Scholar Cross Ref Proceeding of the Fourth IEEE-GCC Conference on Towards Techno-Industrial Innovations.2007:424-428 Google Scholar Burst round robin as a proportional share scheduling algorithm. Journal of Applied Sciences, 2006, 6(9):2036-2039 Google Scholar Cross Ref A new multilevel CPU scheduling algorithm. International Journal on Computer Science and Engineering, 2010, 2(4):1064-1066 Google Scholar An improved round robin scheduling algorithm for CPU scheduling. Rakesh K Y, Abhishek K M, Navin P, et al.Improving Waiting Time of Tasks Scheduled Under Preemptive Round Robin Using Changeable Time Quantum. American Journal of Applied Sciences, 2009, 6(10):1831-1837 Google Scholar Cross Ref Self-adjustment time quantum in round robin algorithm deending on burst time of the now running processes. International Journal of Computer Applications, 2012, 5(5):10-15 Google Scholar A new proposed dynamic quantum with re-adjusted round robin scheduling algorithm and its performance analysis.

Using a timeslice