This preview shows page 1. Sign up to view the full content.
Unformatted text preview: hat the OS routine handling keystrokes requires, on average, 100,000 clock cycles per keystroke. What fraction of the processor load is consumed by all of the keystroke processing? Note that this is a very pessimistic analysis of the load induced by keyboard usage. It’s hard to imagine a real-life scenario with so many users typing this fast. 9.1.1 Process Scheduling and Timer Interrupts
External events such as keystrokes, disk operations, and network activity generate interrupt signals that make the operating system scheduler take over and possibly switch to a different process. Even in the absence of such events, we want the processor to switch from one process to another so that it will appear to the users as if the processor is executing many programs simultaneously. For this reason, computers have an external timer that periodically generates an interrupt signal to the processor. The spacing between these interrupt signals is called the interval time. When a timer interrupt occurs, the operating system schedule...
View Full Document