3.5 Intervals

---

3.5 Intervals

Measurement requires that we have a domain or environment in which we are measuring. In computer systems the environment is the systems clocks and the instruction execution cycle. Another major environment is the high-order systems functions. In order to measure these items we need to focus on their interval of execution. An interval represents a period of time bounding the initiation of an event sequence of interest and the end of this event sequence (Figure 3.3).

Figure 3.3: Example of intervals

In Figure 3.3, the interval I₁ is composed of Event 1's time tag and Event 2's time tag. Intervals are used as a means to measure an event's sequences period of execution or the period of time between such executions (in Figure 3.3, interval 2). Two intervals are the same if they represent the same sequence of events (they are related) and the time interval between the events is equivalent. Two intervals representing two separate sequences of different events can also have equivalent intervals, but they are unrelated.

---