* CPU available is the time interval multiplied by the number of CPU cores. In Figure 4-12, the time interval is 10 minutes, which is 600 seconds (10 _ 60). The number of CPU cores is four, so the CPU power available is 2,400 seconds (600s _ 4 cores, or 4 cores _ 10 minutes _ 60 seconds / 1 minute).

Therefore, the average CPU utilization is only 7% (0.0719 = 172.50 seconds / 2,400 seconds). At only 7% CPU utilization, regardless of the number of CPU cores, the system is operating nowhere near the response-time curve elbow.

Based on v$osstat data, you also can calculate the average operating system CPU utilization. Just remember the CPU consumed requires two samples: the initial and the final. If you take only one sample, you will probably notice the bogus utilization calculation will far exceed 100%. The CPU consumed is the final BUSY_TIME value minus the initial value. The CPU time available will be the sample interval multiplied by the number of CPU cores. And don't forget to convert all time to the same unit, such as seconds.