CPU (MHz)

The CPU (MHz) chart displays CPU usage for the 10 clusters in the datacenter with the most CPU usage.

This chart is located in the Clusters view of the Datacenter Performance tab.

Table 21. Data Counters

Chart Label

Description

<cluster>

Amount of CPU currently in use by the cluster. The active CPU usage is approximately equal to the ratio of the used CPU cycles to the available CPU cycles. The maximum possible value is the frequency of the processors multiplied by the number of cores. For example, a two-way SMP virtual machine using 4000MHz on a host that has four 2GHz processors is using 50% of the CPU (4000 ÷ 4 × 2000) = 0.5). ■ Counter: usagemhz ■ Stats Type: Rate ■ Unit: MegaHertz (MHz) ■ Rollup Type: Average (Minimum/Maximum) ■ Collection Level: 1 (4)

Chart Analysis

A short spike in CPU usage indicates that you are making the best use of cluster resources. However, if the value is constantly high, the CPU demanded is likely greater than the CPU capacity available. A high CPU usage value can lead to increased ready time and processor queuing of the virtual machines on the hosts in the cluster.

If performance is impacted, consider taking the actions listed in Table 22.

Table 22. CPU Performance Enhancement Advice

#	Resolution
1	Verify that VMware Tools is installed on each virtual machine.
2	If the cluster is not a DRS cluster, enable DRS. In Inventory > Cluster > Edit Settings, select Enable VMware DRS.
3	If the cluster is a DRS cluster: ■ Increase the number of hosts, and migrate one or more virtual machines onto the new host. ■ Check the aggressiveness threshold. If the value is low, increase the threshold. This might help avoid hot spots in the cluster.
4	Migrate one or more virtual machines onto a new host.
5	Upgrade the physical CPUs or cores on each host in the cluster if necessary.
6	Enable CPU-saving features, such as TCP Segmentation Offload.
7	Replace software I/O with dedicated hardware, such as iSCSI HBAs or TCP Segmentation Offload NICs.