Clock-driven Scheduling – Advantages and Disadvantages, Real Time System Notes | Sixth Semester, BSc.CSIT | Tribhuvan University (TU)

Clock-driven Scheduling – Advantages and Disadvantages, Real Time System Notes | Sixth Semester, BSc.CSIT | Tribhuvan University (TU)

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Advantages and disadvantages of Clock-driven Scheduling


Advantages
On clock-driven scheduling, decisions on what job executes at what time are made at specific time instants. It has its own advantages and they are as follows;

• Conceptual Simplicity:-
  We can take into account complex dependencies, communication delays, and resource contention among jobs in the choice and construction of static schedule making sure there will be no deadlock and unpredictable delays.
• Jobs can be scheduled according to different static schedules in different modes just by changing the table which represents static schedules.
• No need for concurrency control.
• Precedence constraint and other dependency can be taken care of by the choice of the schedule. So, there is no need for synchronization.
• When workload is mostly periodic and schedule is cyclic, timing constraints can be checked and enforced at frame boundary.
• Context switching and communication overhead can be kept low.
• Relatively easy to validate, test and certify.
• Possible to determine whether the system indeed meets all of its timing requirement by exhaustive simulation and testing.

Disadvantages

• System based on this approach is brittle i.e; relatively difficult to modify and maintain.
• Suited for system which are rarely modified.
• Release time of all jobs must be fixed.
• All combination of periodic task that might execute at the same time must be known a priori so a schedule for the combination can be precomputed.
• Not suitable for system that contain both hard and soft real time application.