IBM z13s, Technical Manual

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Chapter 12. Performance
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12.2 LSPR workload suite
Historically, LSPR capacity tables, including pure workloads and mixes, have been identified
with application names or a
software
characteristic such as:
򐂰 CICS
򐂰 Information Management System (IMS)
򐂰 Traditional online transaction processing workload (formerly known as IMS) (OLTP-T)
򐂰 Commercial batch with long-running jobs (CB-L)
򐂰 Low I/O Content Mix Workload (LoIO-mix)
򐂰 Transaction Intensive Mix Workload (TI-mix)
However, capacity performance is more closely associated with how a workload uses and
interacts with a particular processor
hardware
design. The CPU Measurement Facility (CPU
MF) data that was introduced on the z10 provides insight into the interaction of workload and
hardware design
in production workloads. CPU MF data helps LSPR to adjust workload
capacity curves based on the underlying hardware sensitivities, in particular, the processor
access to caches and memory. This is known as
nest activity intensity
. Using this data, LSPR
introduces three new workload capacity categories that replace all prior primitives and mixes.
LSPR contains the internal throughput rate ratios (ITRRs) for the zBC12 and the previous
generation processor families. These ratios are based on measurements and projections that
use standard IBM benchmarks in a controlled environment. The throughput that any user
experiences can vary depending on the amount of multiprogramming in the user’s job stream,
the I/O configuration, and the workload processed. Therefore, no assurance can be given that
an individual user can achieve throughput improvements equivalent to the stated
performance ratios.
12.3 Fundamental components of workload capacity
performance
Workload capacity performance is sensitive to three major factors:
򐂰 Instruction path length
򐂰 Instruction complexity
򐂰 Memory hierarchy and memory nest
This section examines each of these three factors.
12.3.1 Instruction path length
A transaction or job runs a set of instructions to complete its task. These instructions are
composed of various paths through the operating system, subsystems, and application. The
total count of instructions that are run across these software components is referred to as the
transaction
or
job path length
. The path length varies for each transaction or job, and
depends on the complexity of the tasks that must be run. For a particular transaction or job,
the application path length tends to stay the same, assuming that the transaction or job is
asked to run the same task each time.