6.7

Allocate CPU Resources
To manage workload demands, you can change the amount of CPU resources allocated to a virtual
machine by using the shares, reservations, and limits settings.
A virtual machine has the following user-defined settings that affect its CPU resource allocation.
Limit Places a limit on the consumption of CPU time for a virtual machine. This
value is expressed in MHz or GHz.
Reservation Specifies the guaranteed minimum allocation for a virtual machine. The
reservation is expressed in MHz or GHz.
Shares Each virtual machine is granted a number of CPU shares. The more shares
a virtual machine has, the more often it gets a time slice of a CPU when
there is no CPU idle time. Shares represent a relative metric for allocating
CPU capacity.
Procedure
1 Right-click a virtual machine in the inventory and select Edit Settings.
2 On the Virtual Hardware tab, expand CPU, and allocate the CPU capacity for the virtual machine.
Option Description
Reservation Guaranteed CPU allocation for this virtual machine.
Limit Upper limit for this virtual machine’s CPU allocation. Select Unlimited to specify
no upper limit.
Shares CPU shares for this virtual machine in relation to the parent’s total. Sibling virtual
machines share resources according to their relative share values bounded by
the reservation and limit. Select Low, Normal, or High, which specify share
values respectively in a 1:2:4 ratio. Select Custom to give each virtual machine a
specific number of shares, which express a proportional weight.
3 Click OK.
Change CPU Identification Mask Settings
CPU identification (CPU ID) masks control the CPU features visible to the virtual machine's guest
operating system. Masking or hiding CPU features can make a virtual machine widely available to ESXi
hosts for migration. vCenter Server compares the CPU features available to a virtual machine with the
CPU features of the destination host to determine whether to allow or disallow migration with vMotion.
vSphere Virtual Machine Administration
VMware, Inc. 91