Shortest Remaining Time Next (SRTN) Scheduling

Introduction:
Shortest Remaining Time Next (SRTN) scheduling is a CPU scheduling algorithm that selects the process with the smallest remaining burst time to execute next. It is a preemptive algorithm, meaning that a running process can be interrupted and replaced by a process with a shorter burst time.

Preemptive Scheduling:
SRTN scheduling is a preemptive scheduling algorithm because it allows a running process to be interrupted and replaced by a process with a shorter burst time. The algorithm constantly checks for the process with the smallest remaining burst time and switches to that process if it has a shorter burst time than the currently running process. This ensures that the process with the shortest remaining time is always given priority.

Example:
Suppose we have three processes P1, P2, and P3 with burst times of 5ms, 3ms, and 4ms respectively. Initially, P2 starts executing as it has the smallest burst time. However, after 2ms, a new process P4 with a burst time of 2ms arrives. Since P4 has a smaller burst time than P2, the algorithm preempts P2 and executes P4. This continues until all processes are completed.

Advantages of Preemptive Scheduling:
1. Provides better response time: Preemptive scheduling ensures that processes with shorter burst times are given priority, resulting in faster response times for interactive applications.
2. Better utilization of resources: By allowing processes with shorter burst times to execute first, preemptive scheduling optimizes the use of CPU resources.

Non-preemptive Scheduling:
SRTN scheduling cannot be implemented as a non-preemptive scheduling algorithm. Non-preemptive scheduling does not allow a running process to be interrupted before completing its burst time. In non-preemptive scheduling, the process with the smallest burst time is selected to execute next, but it continues executing until completion without interruption.

Conclusion:
In conclusion, Shortest Remaining Time Next (SRTN) Scheduling is a preemptive scheduling algorithm that selects the process with the smallest remaining burst time to execute next. It provides advantages such as better response times and resource utilization. However, it cannot be implemented as a non-preemptive scheduling algorithm.