Using Supertasks to Improve Processor Utilization in Multiprocessor Real-Time Systems

We revisit the problem of supertasking in Pfair-scheduled multiprocessor systems. In this approach, a set of tasks, called component tasks, is assigned to a server task, called a supertask, which is then scheduled as an ordinary Pfair task. Whenever a supertask is scheduled, its processor time is allocated to its component tasks according to an internal scheduling algorithm. Hence, supertasking is an example of hierarchal scheduling. In this paper, we present a generalized “reweighting” algorithm. The goal of reweighting is to assign a fraction of a processor to a given supertask so that all timing requirements of its component tasks are met. The generalized reweighting algorithm we present breaks new ground in three important ways. First, component tasks are permitted to have non-integer execution costs. Consequently, supertasking can now be used to ameliorate schedulability loss due to the integer-cost assumption of Pfair scheduling. To the best of our knowledge, no other techni...

• Type: Conference
• Year: 2003
• Where: ECRTS
• Authors: Philip Holman, James H. Anderson
• Keywords: Component Tasks, ECRTS 2003, Internal Scheduling Algorithm, Schedulability Loss