When a job finishes, we first swap back jobs from disk before allowing new jobs to start

When a job finishes, we first swap back jobs from disk before allowing new jobs to start. When a job is blocked (either because it wants to do I/O or because our short-term scheduling algorithm says to switch to another job), we have a choice of leaving it in memory or swapping it out. One way of looking at this scheme is that it increases the multiprogramming level (the number of jobs ``in memory'') at the cost of making it (much) more expensive to switch jobs