Time Management in the EPOS Operating System

• Giovani Gracioli UFSC
• Danillo Moura Santos UFSC
• Roberto de Matos UFSC
• Lucas Francisco Wanner UFSC
• Antônio Augusto Fröhlich UFSC

Abstract

One of the tasks of an operating system is to handle time events. Traditionally, time management is based on periodical interrupts from one of the system’s hardware timers (ticks). However, this approach presents limitations, such as lack of precision, large overhead, and large power consumption. These limitations have motivated the use of non-periodical timers (e.g. one-shot timers), specially in specific-purpose operating systems with timing restrictions, such as embedded, real-time, and multimedia systems. This work presents a comparison between single-shot and periodical timer implementations in the time management abstractions in the EPOS operating system. We present the impact of the different implementation in terms of memory footprint, number of context switches, number of interrupt handler executions and run time in different execution scenarios.

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