Timer Interrupt

Timing measurement

• Element events (CPU instructions) have duration of only a few nanoseconds

• However, OS operates on macroscopic time scale (ms)

• Computer flow of time is discrete so it treat events in same time interval occurred simultaneously

Components of time measurements

1. Hardware clock devices
• RTC
• CPU Cycle Counter
• Kernel Clock

2. Kernel data structures and functions to measure time

3. Timing-related system calls