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Shortest job next being executed. Shortest job next (SJN), also known as shortest job first (SJF) or shortest process next (SPN), is a scheduling policy that selects for execution the waiting process with the smallest execution time. [1] SJN is a non-preemptive algorithm. Shortest remaining time is a preemptive variant of SJN.
In the position-based aging model, the processing time of a job depends on the number of jobs processed before it, that is, on its position in the sequence. [17] In sum-of-processing-time-based aging model, the processing time of a job is a weakly-increasing function of the sum of normal (=unaffected by aging) processing times of the jobs ...
The SPT algorithm (Shortest Processing Time First), sorts the jobs by their length, shortest first, and then assigns them to the processor with the earliest end time so far. It runs in time O( n log n ), and minimizes the average completion time on identical machines, [ 1 ] P|| ∑ C i {\displaystyle \sum C_{i}} .
Earliest deadline first (EDF) or least time to go is a dynamic priority scheduling algorithm used in real-time operating systems to place processes in a priority queue. Whenever a scheduling event occurs (task finishes, new task released, etc.) the queue will be searched for the process closest to its deadline.
Least slack time (LST) scheduling is an algorithm for dynamic priority scheduling. It assigns priorities to processes based on their slack time . Slack time is the amount of time left after a job if the job was started now.
Job times must be independent of the job sequence. All jobs must be processed in the first work center before going through the second work center. All jobs are equally prioritised. Johnson's rule is as follows: List the jobs and their times at each work center. Select the job with the shortest activity time.
In a general job scheduling problem, we are given n jobs J 1, J 2, ..., J n of varying processing times, which need to be scheduled on m machines with varying processing power, while trying to minimize the makespan – the total length of the schedule (that is, when all the jobs have finished processing).
The release time, denoted r ij, is determined by adding up the processing times of job j on the machines that precede machine i in the job order of job j. The due date, denoted d ij, is determined by subtracting the processing times of job j on the machines succeeding the machine i in the job order from the makespan. Once all of this is ...