z/VM: CP Commands and Utilities Reference - z/VM - IBM

Usage Notes
scheduled CPU resource; mmm is a decimal real number—no or one decimal
place—from 0.1 to 100 (for example, 20.5% or 80%).
If ABSolute is not specified, the maximum share has the same type as the
minimum share. The mmm% must be specified when the minimum is an
ABSolute value; mmmmm must be specified when the minimum is a RELative
value.
RELative mmmmm
specifies that this user is to receive a target maximum relative share of
mmmmm of the scheduled CPU resource. The operand mmmmm ranges from
1 to 10000.
If RELative is not specified, the maximum share has the same type as the
minimum share. The mmm% must be specified when the minimum is an
ABSolute value; mmmmm must be specified when the minimum is a RELative
value.
NOLimit
specifies that a user’s share of CPU resource is not limited.
SET SHARE
LIMITSoft
specifies that a user’s share of CPU resource is limited. However, there are
times when LIMITSoft users will receive more than their limit. This occurs when
some users are not using all of their shares (for example, they are waiting for
I/O to complete), and there are no NOLimit users and no users who have yet to
reach their limit and can use additional CPU resource.
If a maximum share value was not specified, the user’s minimum share is also
its maximum share of the CPU resource.
LIMITHard
specifies that a user’s share of CPU resource is limited. When LIMITHard is
specified, a user does not receive more than its maximum share of the CPU
resource. If a maximum share is not specified, the minimum share is also the
maximum.
If a maximum share value was not specified, the user’s minimum share is also
its maximum share of the CPU resource.
1. Be aware that a user’s share denotes priority access to the entire set of system
resources, not just CPU. Currently, the following resources are scheduled
according to the share specification:
v CPU
v Main storage
v Paging capacity.
In fact, a bottlenecked resource and a user’s requirement for it determine the
access priority. For example, if storage is constrained, the user receives access
to main storage according to its share. Likewise, if paging is a problem, the user
receives paging service according to its share.
2. An absolute share user is receiving its correct service when the time it would
take to complete a task if it were running alone in the system is the inverse of
its share percentage. For example, if a user receives 50% (1/2) of the system, it
should take no more than twice as long to complete a unit of work as it would if
it were running alone. If it gets 25% (1/4) of the system, it should not take more
than four times what it would running alone. The gauge of relative share
delivery is slightly different. Two relative share users with similar resource
Chapter 2. CP Commands 1383