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Table Of Contents
Table 147. CPU Performance Enhancement Advice (Continued)
# Resolution
5 Upgrade the physical CPUs or cores on the host if necessary.
6 Use the newest version of hypervisor software, and enable CPU-saving features such as TCP Segmentation Offload, large
memory pages, and jumbo frames.
CPU Usage
The CPU Usage chart displays CPU usage of the 10 virtual machines on the host with the most CPU
usage.
This chart is located in the Virtual Machines view of the host Performance tab.
Table 148. Counters
Name Description
virtual_machine Amount of CPU actively being used by each virtual machine on the host. 100% represents all CPUs.
For example, if a virtual machine has one virtual CPU that is running on a host with four CPUs and
the CPU usage is 100%, the virtual machine is using one CPU resource.
virtual CPU usage = usagemhz ÷ (number of virtual CPUs × core frequency)
Note The host's view of the CPU usage, not the guest operating system view.
n
Counter: usage
n
Stats Type: Rate
n
Unit: Percentage (%). Precision is to 1/100%. A value between 0 and 100.
n
Rollup Type: Average (Minimum/Maximum)
n
Collection Level: 1 (4)
Chart Analysis
A short spike in CPU usage or CPU ready indicates that you are making the best use of the virtual
machine resources. However, if the CPU usage value for a virtual machine is above 90% and the CPU
ready value is above 20%, performance is being impacted.
If performance is impacted, consider taking the following actions.
Table 149. CPU Performance Enhancement Advice
# Resolution
1 Verify that VMware Tools is installed on every virtual machine on the host.
2 Set the CPU reservations for all high-priority virtual machines to guarantee that they receive the CPU cycles required.
3 Compare the CPU usage value of a virtual machine with the CPU usage of other virtual machines on the host or in the
resource pool. The stacked line chart on the host's Virtual Machine view shows the CPU usage for virtual machines on the
host.
4 Determine whether the high ready time for the virtual machine resulted from its CPU usage time reaching the CPU limit
setting. If so, increase the CPU limit on the virtual machine.
5 Increase the CPU shares to give the virtual machine more opportunities to run. The total ready time on the host might remain
at the same level if the host system is constrained by CPU. If the host ready time doesn't decrease, set the CPU reservations
for high-priority virtual machines to guarantee that they receive the required CPU cycles.
vSphere Monitoring and Performance
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