The Research And Implementation Of FreeRTOS SMP System On ARM Platform

Under the background of the continuous development of modern technology,the performance requirements of embedded applications for embedded operating systems are increasingly high.With the bottleneck of reducing transistors and improving the main frequency,multi-core strategy has become the best choice to improve the system performance.In the embedded field,FreeRTOS favores by the majority of the industry and has been transplanted to more than 30 hardware platforms relying on its real-time,open source,reliability,ease of use,as well as multi-platform support and other characteristics.According to the global embedded market analysis report,FreeRTOS has been in the forefront for several years,with a wide range of applications.However,at present,there is still no official version of FreeRTOS that supports multi-core.As multi-core processors gradually occupy the market today,multi-core support is imminent.Therefore,it is of great significance to study the multi-core version of FreeRTOS.Based on the official ARM Cortex A53 single-core version of FreeRTOS and the existing embedded multi-core system scheme,this thesis designs and implements a SMP(Symmetric Multi-Processing)system scheme of FreeRTOS on the ARM platform.Under the principle of guaranteeing the original characteristics of FreeRTOS,the first N ready tasks with the highest priority in the operating system can be scheduled and in running state(N is the number of processor cores),and scheduling can be triggered on any core.After the system enters the normal running state,there is no difference between master and slave relations among all cores,and the function and authority are completely equal.And the system can automatically sleep or wake up the processor core according to the number of tasks to save power.In addition,the scheme adopts the global multilevel ready task waiting queue to keep the load balance among cores by the way of global scheduling,which can make full use of the processor resources and improve the system west energy.Through the research and analysis of multi-task priority preemption in SMP mode,this thesis also optimizes the task scheduling strategy,which can reduce the task stack and further improve the processor utilization.Finally,this thesis also realizes the synchronization,mutual exclusion and inter-core communication of SMP system ARMv8,and completes the exploration of multi-core version of FreeRTOS under the execution state of ARMv8's AArch64.Through testing and verification on Raspberry Pi 3B+hardware development board equipped with ARM Cortex A53,the FreeRTOS SMP system scheme proposed in this thesis can successfully handle large quantities of real-time tasks,and ensure the mutual exclusive and correct operation of tasks,and achieve the goal of improving the performance of FreeRTOS system on the basis of guaranteeing the original characteristics of FreeRTOS.