Figure 9-14. Shown is a snippet from both v$system_event (wait events) and v$sys_time_model (v$sys_time_model, DB CPU). Oracle does not include background CPU when calculating "CPU time."

Oracle processes are consuming only 15% of the available CPU capacity. Unless there is another instance or other processes consuming CPU, we would expect the operating system CPU utilization to between around 1% to 10% higher than the Oracle CPU utilization. While not shown in a figure, the v$osstat BUSY_TIME statistic is 228,056 cs, which means all operating system processes during the 60-minute interval consumed 2,280.56 seconds of CPU. Placing the CPU consumption (requirement) value into the utilization formula, we see the operating system CPU utilization is only 16%. So at this low CPU utilization, the operating system overhead is minimal.

Figure 9-15. Shown is an AWR report snippet from the v$sys_time_model used in this exercise. The total CPU consumption (service time) during the 60-minute interval is 2,091.82 seconds. This includes both server process (DB CPU) and background process (background cpu time) CPU consumption.