Limited Direct Execution

In order to virtualize the CPU, the operating system needs to somehow share the physical CPU among many jobs running seemingly at the same time.

Answer

The basic idea is simple, run 1 process for a little while, then run another one. => aka time-sharing .

But hence it’ll raise 2 problems

Caution

• Performance: how to not add excessive overhead to the system
• Control: how can we run processes efficiently while retaining control over the CPU