Explain any four scheduling criteria.

1 Answer

Answer :

1. CPU utilization: In multiprogramming the main objective is to keep CPU as busy as possible. CPU utilization can range from 0 to 100 percent.

2.Throughput: It is the number of processes that are completed per unit time. It is a measure of work done in the system. When CPU is busy in executing processes, then work is being done in the system. Throughput depends on the execution time required for any process. For long processes, throughput can be one process per unit time whereas for short processes it may be 10 processes per unit time.

3. Turnaround time: The time interval from the time of submission of a process to the time of completion of that process is called as turnaround time. It is the sum of time period spent waiting to get into the memory, waiting in the ready queue, executing with the CPU, and doing I/O operations.

4.Waiting time: It is the sum of time periods spent in the ready queue by a process. When a process is selected from job pool, it is loaded into the main memory (ready queue). A process waits in ready queue till CPU is allocated to it. Once the CPU is allocated to the process, it starts its execution and if required request for resources. When the resources are not available that process goes into waiting state and when I/O request completes, it goes back to ready queue. In ready queue again it waits for CPU allocation.

5.Response time: The time period from the submission of a request until the first response is produced is called as response time. It is the time when system responds to the process request not the completion of a process. In the system, a process can Produce some output fairly early and can continue computing new results while previous results are being output to the user.

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