The long-term scheduler executes much less frequently; minutes may sep- arate the creation of one new process and the next. The long-term scheduler controls the degree of multiprogramming (the number of processes in mem- ory). If the degree of multiprogramming is stable, then the average rate of process creation must be equal to the average departure rate of processes leaving the system. Thus, the long-term scheduler may need to be invoked only when a process leaves the system. Because of the longer interval between executions, the long-term scheduler can afford to take more time to decide which process should be selected for execution

The long term scheduler spools processes from the disk and puts them into memory where they fall in line for cpu time