The utilization formula implies a linear relationship between requirements and utilization. In other words, if the requirements double, so will the utilization. When you are asked, "But how do you know it really works like this?" show the graph in Figure 9-7, or better yet, create one yourself. While no real Oracle system will match this perfectly, for CPU-intensive systems, the linearity is very evident.

Figure 9-7 is an example of using SQL executions as the workload (logical IO would have also worked very well). The solid line is the actual sample data plotted, and the dotted line is a linear trend line added by Microsoft Excel. The correlation between the real data and the trend line is 0.9328, which represents a very strong correlation! In the upcoming sections, I will demonstrate how to use this linear relationship when anticipating the impact of a firefighting solution.

Figure 9-7. Shown is a demonstration of the linear relationship between utilization and requirements. This graph is not based on theory or mathematical formulas, but data sampled from a CPU-intensive Oracle system. The solid line is based on the actual sample data, and the dotted line is a linear trend line. Their correlation coefficient is a very strong 0.9328.