Emulating soft real-time scheduling using traditional operating system schedulers

Abstract

Real-time scheduling algorithms are usually only available in the kernels of real-time operating systems, and not an more general purpose operating systems, like Unix. For some soft real-time problems, a traditional operating system may be the development platform of choice. This paper addresses methods of emulating real-tame scheduling algorithms on top of standard time-share schedulers. We examine (through simulations) three strategies for priority assignment within a traditional multi-tasking environment. The results show that the emulation algorithms are comparable in performance to the real-time algorithms and in some instances outperform them.

Measurement of Performance

“…Firm timers together with a preemptible kernel and suitable scheduling have been shown to be effective in supporting time-sensitive applications on a commodity operating system. Priority adjustments allow a measure of control over when processes will run, enabling the emulation of real-time services [1]. This is essentially similar to the implementation of hard real-time support in the kernel, except for the fact that it is done by an external process, and can only use the primitives provided by the underlying commodity system.…”

PETRANET: a Power Efficient Transaction Management Technique for Real-Time Mobile Ad-hoc Network Databases

“…Currently PETRANET does not modify the operating system scheduler, still it sets different priorities for the incoming transactions [5]. The real time scheduler sets priorities based on the transactions' slack time.…”

An Implementation of Budget-Based Resource Reservation for Real-Time Linux

“…There were also many other research and implementation results on the QoS support for real-time applications. In particular, Adelberg, et al [9] presented a real-time emulation program to build soft real-time scheduling on the top of UNIX. Childs and Ingram [10] chose to modify the Linux source code by adding a new scheduling class called SCHED QOS which let applications specify the amount of CPU time per period 1 .…”