Red Hat NETSCAPE MANAGEMENT SYSTEM 4.5 Uživatelský manuál stáhnout pdf (Strana 234)

Resource Management

234

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CPU Resource Management

VMware ESX Server provides dynamic control over both the execution rate and the

processor assignment of each scheduled virtual machine. The scheduler performs

automatic load balancing on multiprocessor systems.

You can manage the CPU resources on a server from the VMware Management

Interface or from the console operating system’s command line.

Proportional-share Scheduling

Proportional-share processor scheduling gives you intuitive control over execution

rates. Each scheduled virtual machine is allocated a number of shares that entitle it to

a fraction of processor resources. For example, a virtual machine that is allocated twice

as many shares as another is entitled to consume twice as many CPU cycles. In

general, a runnable virtual machine with S shares on a processor with an overall total

of T shares is guaranteed to receive at least a fraction S/T of the processor CPU time.

For example, if you are running three virtual machines, each starts with a default

allocation of 1,000 shares. If you want to give one virtual machine half the CPU time

and give each of the other two virtual machines one-quarter of the CPU time, you can

assign 2,000 shares to the first virtual machine and leave the other two at their default

allocations. Since these share allocations are relative, the same effect may be achieved

by giving 500 shares to the first virtual machine and 250 to each of the other two

virtual machines.

You can control relative CPU rates by specifying the number of shares allocated to

each virtual machine. The system automatically keeps track of the total number of

shares, T. Increasing the number of shares allocated to a virtual machine dilutes the

effective value of all shares by increasing T.

Absolute guarantees for minimum CPU rates can be specified by following the simple

convention of limiting the total number of shares allocated across all virtual machines.

For example, if the total number of shares is limited to 10,000 or less, each share

represents a guaranteed minimum of at least 0.01 percent of processor CPU cycles.

The console operating system receives 1,000 shares by default. In most cases, this

should be an appropriate allocation, since the console operating system should not

be used for CPU-intensive tasks. If you do find it necessary to adjust the console

operating system’s allocation of CPU shares, you can use the procfs interface, as

described in this section. Or you can achieve a similar result indirectly, using the

VMware Management Interface, by adjusting the shares of the virtual machines

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Red Hat NETSCAPE MANAGEMENT SYSTEM 4.5 Uživatelský manuál Strana 234