Summary: An Overview of Interrupt Accounting Techniques
for Multiprocessor Real­Time Systems #
Bj˜ orn B. Brandenburg Hennadiy Leontyev James H. Anderson
Abstract
The importance of accounting for interrupts in multiprocessor real­time schedulability anal­
sysis is discussed and three interrupt accounting methods, namely quantum­centric, task­centric,
and processor­centric accounting, are analyzed and contrasted. Additionally, two special cases,
dedicated interrupt handling (i.e., all interrupts are processed by one processor) and timer multi­
plexing (i.e., all jobs are released by a single hardware timer), are considered and corresponding
analysis is derived. All discussed approaches are evaluated in terms of schedulability based on
interrupt costs previously measured on a Sun Niagara multicore processor. The results show
that there is no single ``best'' accounting technique that is always preferable, but rather that the
relative performance of each approach varies significantly based on task set composition, i.e.,
the number of tasks and the maximum utilization.
1 Introduction
System overheads such as time lost to task switches and scheduling decisions must be accounted
for in real­time systems if temporal correctness is to be guaranteed (Cofer and Rangarajan, 2002;
Liu, 2000). Of these overheads, interrupts are notoriously troublesome for real­time systems since
they are not subject to scheduling and can significantly delay real­time tasks.
# Work supported by IBM, Intel, and Sun Corps.; NSF grants CNS 0834270, CNS 0834132, and CNS 0615197; and

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

Collections: Computer Technologies and Information Sciences