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Sangchul HAN Heeheon KIM Xuefeng PIAO Minkyu PARK Seongje CHO Yookun CHO
This letter proves the finish time predictability of EDZL (Earliest Deadline Zero Laxity) scheduling algorithm for multiprocessor real-time systems, which is a variant of EDF. Based on the results, it also shows that EDZL can successfully schedule any periodic task set if its total utilization is not greater than (m+1)/2, where m is the number of processors.
Seongje CHO Suk-Kyoon LEE Sang AHN Kwei-Jay LIN
For real-time systems, multiprocessor support is indispensable to handle the large number of requests. Existing on-line scheduling algorithms such as Earliest Deadline First Algorithm (EDF) and Least Laxity Algorithm (LLA) may not be suitable for scheduling hard real-time tasks on multiprocessors. Although EDF has a low context switching overhead, it can produce arbitrarily low processor utilization. LLA has been shown as suboptimal, but has the potential for higher context switching overhead. We propose new on-line scheduling algorithms Earliest Deadline/Least Laxity (ED/LL) and Earliest Deadline Zero Laxity (EDZL) for identical multiprocessors. We show that ED/LL is suboptimal for multiprocessors and EDZL is suboptimal for two processors. Experimental results show that ED/LL and EDZL have low context switching overhead and low deadline miss rate.