Summary: Supporting Lock­free Synchronization in Pfair­scheduled
Systems #
Philip Holman
Department of Computer Science, University of North Carolina
Chapel Hill, North Carolina 27599­3175 USA
James H. Anderson
Department of Computer Science, University of North Carolina
Chapel Hill, North Carolina 27599­3175 USA
Abstract
We consider various techniques for implementing shared objects and for account­
ing for object­sharing overheads in Pfair­scheduled multiprocessor real­time sys­
tems. Lock­free objects are more economical than locking techniques when imple­
menting relatively simple objects such as bu#ers, stacks, queues, and lists. In this
paper, we explain how to bound the duration of lock­free object accesses under
Pfair multiprocessor scheduling. We also show that these durations can be reduced
by combining tasks into supertasks, i.e., a group of tasks that are scheduled as a
single entity; this is because the use of supertasks can prevent interfering tasks from
executing in parallel, thereby reducing the worst­case durations of object accesses.
Indeed, we show that supertasking can even enable the use of less costly unipro­
cessor synchronization techniques when all tasks sharing an object reside in the

Source: Anderson, James - Department of Computer Science, University of North Carolina at Chapel Hill

Collections: Computer Technologies and Information Sciences