CPU utilization refers to the level of CPU used by different processes in the system. When a CPU is over used, alerts are sent to the administrators for fixing the problem as CPU is utilized only few by a few processes and the rest of the processes are in queue for a long time. In a shared hosting environment, administrators have to check CPU usage for a hosting account. They generally limit each account to no more than 25% of CPU utilization. In a shared hosting environment when CPU utilization increases, it degrades the overall performance of the system.
The concept of multiprogramming is used for improving the CPU utilization. When there are multiple processes running then CPU utilization can be calculated by the formula:
CPU utilization = 1 – p^n
where, p is the time spend by a process and n is the number of processes simultaneously in memory. Here, n is also known as degree of multiprogramming.