2. PERFORMANCE REPORTING ANALYSIS › 2.9 WLM Goal Mode Analysis › 2.9.2 Usage Guidelines › 2.9.2.1 LP Related Metrics

2.9.2.1 LP Related Metrics

The following metrics were added to enhance the understanding
and management of z/OS based LP resources:

Weighted LP   This is the effect capacity of the LP under
Cap. (MSUs)   study, expressed in MSUs per hour.  Because of
              LP weight enforcement, the actual capacity of
              an LP to do work is reduced in proportion to
              its defined weight.  Quantifying this value
              helps in LP sizing and in understanding why
              performance objectives might not be met.

Weighted LP   The share of active logical processors that is
Share Pct.    available to this LP, expressed as a
              percentage. This value is used in computing
              other metrics within the reports.

No. of Avail- The total number of processors available for
able Procs.   use by this LP. This is not a computed value,
              but rather is the CA MICS data element CPUNOCPU
              and includes all types of processors configured
              in the logical partition (standard CP and
              special processors).

CPs Required  The minimum number (or fraction) of CPs needed
for LP Wgt.   to ensure that the LP can actually sustain its
              weighted share. Round this value up to the next
              integer when defining the LP size. If this
              value is greater than the number of CPs defined
              for the LP, the LP will not have sufficient
              capacity to support its weighted share, and
              performance may suffer.  If this value is
              significantly lower than the number of CPs
              defined for the LP, then performance of large
              processing tasks, such as online application,
              may be affected.

LP Shr. Proc. This value is sometimes referred to as "Short
Use Ratio     CPs." It is a ratio of the MVS Busy time
              (CPUTOVBT) to the LP Busy time (CPUTOBTM) for a
              reporting interval. The purpose of this metric
              is to demonstrate the lack of processor
              resources in an easy way that can be presented
              to non-technical personnel. In general, a value
              greater than 1.25 is cause for concern,
              especially if performance objectives are not
              being met.

Weighted CP   The effective speed of an individual CP within
Speed (MSUs)  the LP configuration. This value is a function
              of the CPs Required for LP Wgt. metric defined
              above and the number of CPs active for the LP.
              The total weight for the LP is spread equally
              among all active CPs, causing each CP to be
              dispatched by PRSM for an interval based on the
              Weighted LP Share percentage mentioned above.
              Having more CPs active than are required for a
              given weighted LP capacity will result in the
              effective CP speed being reduced and can result
              in performance degradation. IBM's Intelligent
              Resource Director facility can attempt to
              control the number of active CPs based on WLM
              Goal Mode service objectives to help ensure
              that the number of active CPs is optimal for
              a given workload.

Percent Ready The number of address spaces that are waiting
Tasks Wait    for dispatch on a CP, expressed as a
              percentage. If the LP Shr Proc. Use Ratio value
              is high and this value is more than 50%, then a
              significant processor resource shortage exists
              and performance may be affected.