A task is said to be schedulable if the total execution time of all its tasks is less than the farthest deadline. Criteria for selecting scheduling algorithm are -

i) CPU Utilization – Scheduling algorithm should always utilize CPU efficiency.

ii) Throughput – This indicates the number of tasks executed per unit time of time. Throughput of a good scheduler should be high.

iii) Turnaround time – It is the amount of time taken by a task for its completion. It includes time required to perform various activities-

• Time spent to access memory
• Time spent in ready queue
• Time spent in completing I/O operations
• Time spent in execution

iv) Waiting time – The time spent in ‘Ready’ queue to get COU time for execution is called waiting time.

v) Response time – The time elapsed between creation of a task and first response is called response time.