Research On Real-time Performance Of The Embedded Linux Kernel

In numerous embedded operation systems, embedded Linux system is widely used inembedded system development because of its opened source codes, good scalable andportability performance. However, Linux is firstly designed as a time-sharing system toimprove the system throughput and overall performance. It is difficult to meet somerequirements of embedded real-time application systems, so it is necessary to research thereal-time performance of embedded Linux kernel.Based on the research of Linux kernel, the advantages of Linux as embeddedoperation system and the shortcomings of real-time performance are analyzed in the paper,and the main emphasis is how to improve the real-time performance of Linux. The taskscheduling strategy is the critical issue of real-time performance of Linux. According to thetask_struct definition of Linux, the paper use multi-level feedback scheduler for nonreal-time tasks and use FIFO (First Input First Output) and RR (Round-Robin) schedulerfor real-time tasks. The paper put forward two methods to improve the real-timeperformance of embedded Linux kernel. (1) Using dual kernel, RT-Linux is transplanted toLinux as the real-time kernel to process the real-time tasks. The system uses virtualinterrupt mechanism and interrupt response is processed by real-time kernel to solve theproblem of the interrupt mask. (2) Loading real-time scheduler improve systemperformance in terms of Linux task scheduling mechanism. For static periodic task, thesystem uses the RM scheduler，and it assigns short-period task higher priority. Fordynamic task, the system uses the EDF scheduler. According to the task of the earliestdeadline, it assigns early-deadline task higher priority. The test results indicate that themethods can effectively improve the real-time performance of embedded Linux kernel.