If the database server is the bottleneck, then the database server bottleneck will be either CPU, IO, or some lock/blocking (for example, enqueues) issue. Your graph will reflect either the general queue time increase of an IO bottleneck or the steep and dramatic elbow of a CPU bottleneck. Figure 9-8 is a good guide, as it contrasts both the CPU and IO bottlenecks.

Based on v$osstat data shown in Figure 9-6 and the reporting interval shown in Figure 9-2, we calculated in the subsequent sections the server is running at 100% CPU utilization. While the wait event situation is not shown, the Statspack report shows the top wait event is clearly CBC latch contention. Based on the instance CPU consumption data shown in Figure 9-3, the reporting interval shown in Figure 9-2, and the CPU core number shown in Figure 9-6, we calculated an Oracle CPU utilization of 94%. Clearly, there is a CPU bottleneck.

When you choose an appropriate unit of work, the response-time graph will be a good representation of the real system. This will make presenting the graph very natural and understandable, and will naturally lead into your performance solutions discussion.