z/VM LPAR Entitlement Calculator

LPAR Entitlement Calculator

Here is a tool you can use to do what-if calculations as regards the configuration of the LPARs on your CPC.

In the form below, type in the names, core counts, weights, and polarities of your LPARs. Then click the "Calculate" button. We will calculate the entitlements and the counts of VHs, VMs or HZs, and VLs.

Do this for one specific type of core: CP, IFL, whatever. If your CPC has cores of multiple types, do a what-if calculation for each type.

Instructions:

Under Shared physical cores, type in the number of physical cores your CPC has, deducting for any dedicated LPARs you might have. For example, if you have 15 physical IFL cores and you have two dedicated LPARs configured with 7 IFL cores altogether, your number of shared physical cores is 15-7 = 8.
In the LPARs table,
- Under Cores, type in the number of processors you requested in the LPAR's activation profile. (Yes, the SE/HMC tab says "Processors", but you are really requesting cores.)
- Under Weight, type in the weight you requested for those processors.
- Under Polarity, select either V for Vertical or H for Horizontal, depending upon how you plan to run the LPAR.
When you have finished typing, click on the Calculate button.

The information submitted is not saved or recorded.

Fill out the form, then click the Calculate button:

Number of shared physical cores:

Enter details about your LPARs:

A form used to calculate the CPU entitlement for your z/VM LPARs.
Name	Cores	Weight	Polarity

Some tips:

Entitlement is the total amount of core power the LPAR can use whenever it wants. Each increment of 100% represents one physical core's worth of power. So, for example, an entitlement of 381% means the LPAR can use 3.81 physical cores' worth of power whenever it wants.
An LPAR can use beyond its entitlement only when other LPARs are using less than their entitlements.
Each vertical-high (VH) logical core is entitled to 100% of a physical core. In other words, a VH logical core can run whenever it wants, as much as it wants.
Each vertical-medium (VM) or horizontal (HZ) logical core is entitled to a percentage of a physical core within the range 0-100% (0 not included and 100 included), as displayed in the column Ent(VM or HZ). A VM or HZ logical core can use beyond its entitlement, but only when some other core is using less than its entitlement.
Each vertical-low (VL) logical core is entitled to 0. A VL logical core can run only when some other core is using less than its entitlement.
If an LPAR has unusable entitlement, either it doesn't have enough logical cores defined to use its entitlement, or, if you prefer, it has too much entitlement for its number of logical cores defined. In either case, the configuration is in error and the unusable entitlement is going to waste. Redo the configuration.
Certain CEC-scope events will change the LPARs' entitlements. Some examples of such events are activating an LPAR, deactivating an LPAR, changing an LPAR's weight, and changing the number of shared physical cores.
When an LPAR's entitlement changes, the entitlements of its logical cores will change. For example, some VHs might become VMs.
Certain LPAR-scope events can cause the entitlements of the LPAR's logical cores to change. Some examples of such events are the issuing of CP VARY OFF CORE and the issuing of CP VARY ON CORE.
For best results with VMs and VLs, z/VM customers should use CP SET SRM UNPARKING MEDIUM. For more information, read this article.
In a running z/VM LPAR, one can use Perfkit FCX298 PUORGLOG to see that LPAR's polarizations and entitlements.
If you have a MONWRITE file that was collected in an LPAR that had Global Performance Data Control (GPDC) enabled, you can use our CALCENT tool to process that MONWRITE file and thereby see how your CPC was configured when the MONWRITE file was collected. Here is an example of the output of CALCENT, and here are the column definitions.
For a lot more information, see this presentation.