When gathering CPU requirements, we typically look at the time model system statistics (v$sys_time_model) or the instance statistics (v$sysstat). In previous chapters, I have presented how to gather CPU requirements from the v$sesstat, v$sysstat, v$ses_time_mode, and v$sys_time_model views.

The second part of Figure 9-2 shows a few instance statistics from a Statspack report. Based on this data, during the Statspack reporting interval, Oracle processes consumed-that is, required-1,675,794 centiseconds of CPU, which is 16,757.94 seconds of CPU.

The time model system statistics provide more accurate CPU consumption details. Figure 9-3 shows the Time Model System Stats section of the Statspack report shown in Figures 9-1 and 9-2. According to the time model statistics, Oracle processes (server and background) consumed 16,881.6 seconds of CPU during the reporting interval of 149.97 minutes. Notice that in this case, there is little difference between the instance (shown in Figure 9-2) and time model (shown in Figure 9-3) CPU consumption statistics.