CPU Configuration Guidelines for vPars

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Figure 10. The CPU utilization objective is achieved with 4 CPU’s.
3.2 Determining Maximum CPU Configuration
The objective of this section is to experimentally determine the maximum number of CPU’s that a
specific workload will need in order to satisfy a 60% increase in workload from the steady state run
made in the previous section.
With top running, increase the file system and disk stress workload by approximately 60% and
observe the CPU utilization of the system. The average utilization across the 4 CPU’s in the system is
94.2% (100% - 5.8% idle) as shown in Figure 11, which is well above the stated objective of 60%.
Add a CPU from the real time processor set to the default processor set (pset 0) as shown in Figure
12.
Now run the file system and disk stress on the 5 CPU’s in the default processor set. The CPU
utilization for this run must be summed across the 5 CPU’s in the default processor set and then
averaged (see Figure 13) to come up with 25.8% idle which translates to 74.2% utilized. Adding
another CPU to the default processor set and running the workload against it produced an average
idle of 36.8% which translates to 63.2% utilized (Figure 14). This is close to the stated objective so 6
CPU’s will be the maximum number of CPU’s that are need for this workload.
Figure 11. CPU utilization has exceeded the stated objective.