Installation guide

www.vmware.com
388
VMware ESX Server Administration Guide
CPU Resource Management
VMware ESX Server provides dynamic control over both the execution rate and the
processor assignment of each scheduled virtual machine. The ESX Server scheduler
performs automatic load balancing on multiprocessor systems.
You can manage the CPU resources on a server from the VMware Management
Interface, from the procfs interface on the service console and the VMware
Scripting API.
For each virtual machine, you can define a minimum and maximum amount of CPU
that a virtual machine can use, guaranteeing a percentage of the CPU resource,
whether or not there is contention. You also allocate CPU shares to specify the relative
importance of virtual machines.
If you have also purchased the VMware Virtual SMP for ESX Server product and your
guest operating system is SMP-capable, then you can also control whether the virtual
machine runs on one or two CPUs, and restrict a virtual machine to run only on
certain physical CPUs. For more information on the VMware Virtual SMP for ESX Server
product, contact VMware, Inc. or your authorized sales representative.
For additional information on CPU management by VMware ESX Server, see the
cpu(8) man page.
Allocating CPU Resources
Three basic parameters control the allocation of CPU resources to each virtual
machine:
• Its minimum rate — min
The minimum CPU percentage represents an absolute fixed lower limit of a
single physical CPU’s processing power. The virtual machine will always be able
to use this minimum percentage of a CPU’s resources, regardless of what else is
happening on the server. The system uses an admission control policy to enforce
this guarantee. You cannot power on a new virtual machine if it is not possible to
reserve its minimum CPU percentage.
• Its maximum rate — max
The maximum CPU percentage represents an absolute fixed upper limit on the
consumption of a single physical CPU’s processing power. The virtual machine
will never consume more than this maximum percentage of a CPU’s resources,
even if there is idle time on the system.
• Its shares allocation