6.7

Table Of Contents
Table 198. CPU Performance Enhancement Advice (Continued)
# Resolution
7 Reduce the number of virtual CPUs on a virtual machine to only the number required to execute the workload. For example, a
single-threaded application on a four-way virtual machine only benefits from a single vCPU. But the hypervisor's maintenance
of the three idle vCPUs takes CPU cycles that could be used for other work.
8 If the host is not already in a DRS cluster, add it to one. If the host is in a DRS cluster, increase the number of hosts and
migrate one or more virtual machines onto the new host.
9 Upgrade the physical CPUs or cores on the host if necessary.
10 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 (MHz)
The CPU Usage (MHz) chart displays virtual machine CPU usage.
This chart is located in the Home view of the Virtual Machine Performance tab.
Table 199. Data Counters
Chart Label Description
Usage Amount of actively used virtual CPU.
Note The host's view of the CPU usage, not the guest operating system view.
n
Counter: usagemhz
n
Stats Type: rate
n
Unit: MegaHertz (MHz)
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 1100. 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.
vSphere Monitoring and Performance
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