Embedded Operating System Process Scheduling And Realization

Embedded system has been widely used in every field and its speed ofdevelopment is amazing, as the kernel of its software, the embeddedoperating system is the hotspot of research in information industry. Thisthesis is based on the study of how to rebuild embedded Linux in differentapplication environment.RM(Rate Monotonic) algorithm is a typical static priority real timescheduling algorithm, the mission's priority is determined by its period,the longer period, the lower priority. Firstly, the thesis analyzes theprocess scheduling principle of hinux and some critical problems in thereal time improvement; To realize a real time operating system, andbecause hinux has a large kernel, its developing tools are hard to use,it's not easy to realize a real time operating system in few days. So,on the basis of analysing Schedulability test of RM, we use the necessaryand sufficient condition of schedulability which is given by hehoczky torealize RM algorithm under Windows environment, we test the algorithm byscheduling the appointed processes cluster, and analyze the results ofthe experiment, we can see the algorithm is preemptive from the result,and it can meet the needs of real time attribute. The algorithm can beused in embedded Linux according to the specified real time system.To solve the problems of the fairness and real time attributes betweendifferent user of Linux, on the bases of analyzing Fair-share schedulingalgorithm, the thesis advances an improved Fair-Share Scheduling——UTRSalgorithm(User Timeslice Round Scheduling) which is aimedat solving theproblem of priority reverse, we realize it in Linux 2.4.20 kernel, andcompare it with FSS in algorithm performance. By validating, the algorithmis satisfied with the fairness between different users.