OCR A Level Computer Science
1.2.1d: Scheduling: round robin, first come first served, multi-level feedback queues, shortest job first and shortest remaining time.
1.2.1d: Scheduling: round robin, first come first served, multi-level feedback queues, shortest job first and shortest remaining time.
| Keyword | Definition |
|---|---|
| First Come First Served (FCFS) | A scheduling algorithm that assigns tasks to the CPU in the order in which they arrive. This ensures that tasks are executed in the order in which they are submitted, but can lead to long wait times for tasks that arrive later in the queue. |
| Multi-Level Feedback Queues (MLFQ) | A scheduling algorithm that uses multiple queues to organize tasks, with each queue having a different priority level. Tasks are assigned to the queue based on their priority, and the CPU executes the tasks in each queue in turn. This allows the CPU to prioritize tasks with higher priority and improve the overall performance of the system. |
| Round Robin | A scheduling algorithm that assigns tasks to the CPU in a circular fashion, giving each task a fixed amount of time to execute before moving on to the next task. This ensures that each task gets a fair share of the CPU's time, but can lead to poor performance if some tasks take longer to execute than the time slice allocated to them. |
| Scheduling | The process of determining which tasks should be executed by a computer's CPU and in what order. Scheduling algorithms aim to optimize the use of the CPU and other resources to ensure that tasks are completed efficiently and in a timely manner. |
| Shortest Job First (SJF) | A scheduling algorithm that assigns tasks to the CPU based on their estimated execution time. Tasks with shorter estimated execution times are given higher priority and executed before tasks with longer estimated execution times. This can improve the overall performance of the system, but can be difficult to implement in practice because it requires accurate estimates of task execution times. |
| Shortest Remaining Time (SRT) | A scheduling algorithm that is similar to SJF, but takes into account the remaining execution time of each task rather than the estimated execution time. This allows the CPU to adjust its scheduling decisions as a task is executing, and can improve the overall performance of the system. However, like SJF, it requires accurate estimates of task execution times and can be difficult to implement in practice. |
