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Schedulable Utilization Bounds for EPDF Fair Multiprocessor Scheduling

Summary: Schedulable Utilization Bounds for EPDF Fair
Multiprocessor Scheduling
UmaMaheswari C. Devi and James H. Anderson
Department of Computer Science,
The University of North Carolina, Chapel Hill, NC 27599, U.S.A.
Email: {uma,anderson}@cs.unc.edu
Abstract. The earliest-pseudo-deadline-first (EPDF) algorithm is less expensive
than other known Pfair algorithms, but is not optimal for scheduling recurrent
real-time tasks on more than two processors. Prior work established sufficient
per-task weight (i.e., utilization) restrictions that ensure that tasks either do not
miss their deadlines or have bounded tardiness when scheduled under EPDF. Im-
plicit in these restrictions is the assumption that total system utilization may equal
the total available processing capacity (i.e., the total number of processors). This
paper considers an orthogonal issue -- that of determining a sufficient restriction
on the total utilization of a task set for it to be schedulable under EPDF, assuming
that there are no per-task weight restrictions. We prove that a task set with total
utilization at most 3M+1
is correctly scheduled under EPDF on M processors,
regardless of how large each task's weight is. At present, we do not know whether


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


Collections: Computer Technologies and Information Sciences