Interarrival Time Improvement for Timer Interrupts

• Main Authors: Zhi-Guo Shao, 邵治國
• Other Authors: Chih-Wen Hsueh
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/55222557991181627256

碩士 === 國立中正大學 === 資訊工程研究所 === 91 === In a real-time system, timing constrains of real-time tasks must be satisfied otherwise it might not only be valueless but also sometimes harmful. Thus, fine timing control is an important feature in a real-time system. A simple approach to do the fine control is to improve interarrival time of timer interrupts i.e. reduce interarrival time and increase its timing accuracy. There are basically two modes to generate timer interrupts, periodic and aperiodic. Some previous works use the aperiodic mode to improve the interarrival time, however it is limited by the setup time of hardware timers. To solve the problem, we study and analyze system architectures of uniprocessor and multiprocessor with multiple hardware timers where timer interrupts are generated aperiodically. Furthermore, to reduce the overhead caused by aperiodic timer interrupts, we propose an adjustable periodic method (APM) using periodic mode. Experiments show that APM can reduce about five percentages of the overhead. In order to improve timing granularity and accuracy, related system issues on kernel, software timer and system time are also presented.