The use of communication-closed layers to support imprecise scheduling for distributed, real-time programs

The concept of communication-closed layers (CCL) of distributed programs that was introduced by the author (1989) is adapted for scheduling real-time tasks in a tightly-bound environment. A simple scheduling mechanism for tightly-bound concurrent programs based on CCL is proposed. This scheduling strategy supports an imprecise computation approach and hence it can be used for real-time systems where deadlines are met with acceptable precision. It is flexible because the priorities given to the tasks within a layer can be controlled by different factors and they are user defined. Logical units for scheduling are decided at the design phase using layering and hence the programmer has more control over scheduling of the program rather than writing programs that suit a particular scheduler. This scheduling mechanism is general and can be utilized for single or multi-processor systems in a centralized or distributed environment