Affiliations: College of Information Engineering, China Jiliang
University, Hangzhou 310018, China | College of Computer Science, Zhejiang University,
Hangzhou, Zhejiang, 310027, China | Faculty of Informatics & Electronics, Zhejiang
Sci-Tech University, Hangzhou, Zhejiang, 310018, China
Abstract: In real-time systems, an efficient and stable implementation of
timer is crucial to the timing requirements of tasks. The traditional methods
take O(n^{2}) time overhead to maintain timers in the
periodic task model. In this paper, we present a new implementation method –
S-Method, which takes O(n) time overhead. This method calculates all
trigger instants of periodic tasks within a hyperperiod off-line, and assigns
these instants to corresponding periodic timers. The timer system checks
whether a trigger instant arrives in the timer Interrupt Service Routine (ISR),
and activates tasks periodically without additional timer update overhead, such
as deletion and insertion for new timeout. Experiments show that this method
can reduce the time of timer update and increase stability and predictability in timer update time.
