Relative Nest Intensity; The Traditional Factors That Were Used To Categorize Workloads - IBM z13s Technical Manual

RNI reflects the distribution and latency of sourcing data from shared caches and memory, as
shown in Figure 12-3.
Microprocessor
Figure 12-3 Relative Nest Intensity
Many factors influence the performance of a workload. However, usually what these factors
are influencing is the RNI of the workload. The interaction of all these factors results in a net
RNI for the workload, which in turn directly relates to the performance of the workload.
These factors are tendencies rather than absolutes. For example, a workload might have a
low I/O rate, intensive processor use, and a high locality of reference, which all suggest a low
RNI. But it might be competing with many other applications within the same LPAR and many
other LPARs on the processor, which tend to create a higher RNI. It is the net effect of the
interaction of all these factors that determines the RNI.
The traditional factors that were used to categorize workloads in the past are listed along with
their RNI tendency in Figure 12-4.
Low Low
Batch Batch
Low Low
Single Single
Intensive Intensive
Low Low
High locality High locality
Simple Simple
Extensive Extensive
Figure 12-4 The traditional factors that were used to categorize workloads
Little can be done to affect most of these factors. An application type is whatever is necessary
to do the job. The data reference pattern and processor usage tend to be inherent to the
nature of the application. The LPAR configuration and application mix are mostly a function of
what must be supported on a system. The I/O rate can be influenced somewhat through
buffer pool tuning.
However, one factor,
effect on RNI. This term refers to the number of address spaces (such as CICS
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IBM z13s Technical Guide
The "Nest"
How Often? How Far?
L1MP
L2LP
L1
L3P L4LP
Design Memory Hierarchy or Nest

Relative Nest Intensity

Relative Nest Intensity
Data Reference Pattern Data Reference Pattern
LPAR Configuration LPAR Configuration
Software Configuration Tuning Software Configuration Tuning
software configuration tuning
How intensely this part of the
L2RP
MEMP
L4RP
Application Type Application Type
IO Rate IO Rate
Application Mix Application Mix
CPU Usage CPU Usage
Dispatch Rate Dispatch Rate
, is often overlooked but can have a direct
architecture is utilized
RNI
High High
Transactional Transactional
High High
Many Many
Light Light
High High
Diverse Diverse
Complex Complex
Limited Limited