Earliest Due Date (Edd) This Scheduling Method

Earliest Due Date (EDD)

This scheduling method is suitable for print jobs with strict deadlines. This scheduling rule orders the sequence of print jobs to be performed from the print job with the earliest due date to the print job with the latest due date (Hochbaum, 1999). EDD establishes processes in priority queue and whenever a scheduling event occurs and is released, the queue is then screened to get the next task closest to its deadline. The chosen task is then, next scheduled for execution in order to meet its corresponding deadline. Since it support fixed priorities, it is easy to predict whether the overload conditions will meet the deadlines. The processing time may be measured in hours, days, weeks or months depending on the nature of the print job. Review of historical performances of similar events and tasks is critical in establishing accurate estimated finish time. The most significant aspect in this method is print job flow time, which is the length of time it takes for an order to complete from the order placement.

Shortest Processing Time (SPT)

The SPT is a sequencing process, which assigns print jobs according to their processing time durations. This method is simple because projects in the processing line are ranked by time it takes to complete them, here, the print job with the shortest processing is considered first while the print job with the longest time is done last (Rose, 2001). This method is suitable when minimization of the average flow time is required; it reduces cycle times of each print job. In addition, for effective performance, SPT requires initial time estimation for each print job. Whenever a machine is freed, the shortest print job ready at the time will begin processing.

In the single machine environment with ready time at 0 for all print jobs, SPT is most suitable in minimizing the flow time. It helps minimize the maximum waiting time and the mean lateness of any individual print job ( Torres, Lopez & Wojciechowski 2008).

Nevertheless, SPT is not suitable in situations where there are many orders. It is however useful in situations that would result in several delays with most print jobs having longer processing time. In addition, SPT is likely to result in tardiness and long waiting time for most processes that may be important but have longer processing time.

Longest Processing Time (LPT)

LPT is a print job transmission rule that allocates the highest priority to jobs with the largest processing time. By scheduling the longest print job first, schedulers reduce the number of outstanding long print jobs at the end of the schedule. The longest processing time rule orders the print jobs in the order of decreasing processing times. Whenever an activity is completed, the largest print job ready at the time will be dispatched for execution. This method is used to find the minimum make span of a schedule. It schedules the longest print jobs first so that no one large print job remains uncompleted at the end of the schedule that may drastically lengthen the completion time of the last print job (Kleinrock, 1975). Typically, LPT is the worst way to perform scheduling since it arranges print jobs from the longest to the shortest. In most cases, this schedule fallout into a larger average flow time than expected.

First-Come, First-Served (FCFS)

FCFS is a scheduling policy where client requests are attended to in the order to arrive without biases or preferences. This print job priority method processes print job orders that arrive at a production center first (University of Iowa, 2009). Nevertheless, the arrival time is the determinative factor in this scheduling rule. Often described as the simplest print job-sequencing technique, FCFS, unlike SPT and LPT requires no time estimation for scheduling. If the first come, first serve option is toggled then the program will schedule the print jobs from top of the list to bottom of the list.