Longest Job First (LJF) is a non-preemptive scheduling algorithm. This algorithm is based upon the burst time of the processes. The processes are put into the ready queue based on their burst times i.e., in descending order of the burst times. As the name suggests this algorithm is based upon the fact that the process with the largest burst time is processed first. The burst time of only those processes is considered that have arrived in the system until that time.
1. This algorithm gives very high average waiting time and average turn-around time for a given set of processes. This may lead to convoy effect.
2. It may happen that a short process may never get executed and the system keeps on executing the longer processes.
3. It reduces the processing speed and thus reduces the efficiency and utilization of the system.
Checkout the simulation of Longest Job First