* Oracle consumed 93% of the available database server CPU capacity, which contains 12 CPU cores. Utilization is simply consumption divided by capacity. The total CPU capacity equals the interval duration (60 minutes) multiplied by the 12 CPU cores; that is, 720 minutes, or 43,200 seconds. Said another way, within any one-hour period, a 12 CPU core server can provide up to 720 minutes of CPU power. Statspack showed Oracle CPU consumption was 39,960 seconds. Therefore, Oracle used 39,960 seconds of the available 43,200 seconds of CPU, which is 93%.15

If you were to draw the response-time curve, it would look something like Figure 1-4. (Keep in mind this is an abstraction, and I took certain liberties, which will be fully explained in Chapters 5 and 9.) Looking at the response-time curve in Figure 1-4, you can see that, at an arrival rate (workload) of 1,510 uc/sec, there is a clear problem, because the system is operating in the elbow of the curve. There is a possibility that service levels are still being met, so this situation does not represent a problem. However, just a slight increase in the arrival rate (workload) will very likely cause a service level breach.

Figure 1-4. This response time curve is based on 12 CPU cores with a service time of 0.0074 sec/uc. In this example, the arrival rate is 1,510 uc/sec, which mathematically equates to an average queue time of 0.0059 sec/uc, an average CPU utilization of 93%, and a response time of 0.0133 sec/uc.