Implementation and evaluation of a best-effort scheduling algorithm in an embedded real-time system

This paper describes an implementation and the performance evaluation of the DASA/ND best-effort scheduling algorithm [4] in the muClinux(TM)/muCsimm(TM) micro-controller system Experimental results under synthetic workload show that in some cases, the DASA/ND scheduler outperforms both the EDF (Earliest Deadline First) and the RMS (Rate Monotonic Scheduling) schedulers [7]. Meanwhile, the system performance gracefully degrades as the aggregate CPU load increases. However, the scheduling overhead, in general, is not negligible, which may lead to poorer performance than non best-effort scheduling algorithms. It is found that the scheduling overhead strongly depends on the task set properties. Using the Regression Analysis technique, we developed a statistical model accounting for the scheduling overhead. We show that this model, combined with a simulation tool can well predict the system performance.