An Analytical Survey of Real Time System Scheduling Techniques

Real-time systems are systems that are time dependent. The time dependency nature of these systems compared to conventional operating systems such as the Unix time sharing multiuser and multitasking systems and its variants, single user and multitasking Microsoft windows systems and single user and single task palm and handheld device systems has given rise to several techniques in the management of computer resources. Scheduling is that all-important functionality of the operating system that ensures Operating systems and computers resources are managed in such a way as to ensure none of the competing processes is starved of such resources at any given point in time. In real time system, scheduling is effected using certain criteria that ensure processes complete their various tasks at a predetermined stipulated time of completion. The scheduling techniques depend on the two basic types of the existing real time systems; Hard and Soft Real-Time System. The pre-determined time of completion of tasks must be met in Hard Real Time Systems otherwise the resultant effect can be disastrous. Tasks in Real Systems that fail to complete within the pre-determined completion time are tolerable but not often desirable. In these two known types of Real-Time System, pre-emption and multitasking techniques are often used. In this study, a critical analysis of these scheduling techniques and their performance (strengths and weaknesses) in existing systems will be carried out and highlighted. The various scheduling techniques and their associated parameters are examined and analysed. In addition, a survey of known scheduling techniques in real time systems and approaches used by the different techniques are presented.