C Event Set Descriptions for CPU Metrics

This appendix contains descriptions for the output of each event set available when you use the cpu measurement.

NOTE: The information provided in this appendix for each report description is the same information you receive when you use the --infooption to append help to the end of text reports, or when you use this command:

$ caliper info -r event-set

For more information, see “cpu Measurement Report Description ” (p. 183).

brpath Event Set

The brpath event set provides information on the dynamic mix of branch types (IPREL, indirect, and return), branch path distribution, branch density, and so forth.

If you use this event set, the default is to make the measurements irrespective of CPU operating state (that is, user, system, or interrupt states). By default, the idle state is not included in the measurement. You can use command-line options to limit the scope of the measurement. Specifically, you can:

•Limit measurement to a specific privilege level: -m event_set[:alluserkernel]

•Include idle: --exclude-idle False

•Exclude the interruption state: --measure-on-interrupts off

•Only measure the interruption state: --measure-on-interrupts only

Metrics Available from this Measurement

The following metrics are available from this event set. These descriptions do not take into account any command-line options you might use.

The metrics are:

•Raw CPI

The raw CPI is computed using all instructions retired. This includes nops and predicated off instructions. The relationship between effective and raw CPI values can be obtained from the cpi measurement.

•Branch Per Inst

This is the ratio of the number of total instructions and total branches retired. The instructions retired includes nops and predicated off instructions. The cpi measurement can be used in conjunction with this measurement to estimate the ratio of the number of branches and effective instructions. The Itanium 2's PMU branch semantics considers predicated off branches as retired untaken branches. Thus, predicated off branches are included as part of the denominator in this derived metric.

•Branch Distribution

This metric provides a distribution of branches among the three major branch categories: IPREL, Indirect, and Return. The IPREL category is further subdivided into call and noncall branch categories. The Indirect category includes indirect call and noncall indirect branches. The Return category covers all forms of return branches.

◦%IPREL Call Branch

This metric provides the percentage of IPREL call branches among all branches.

◦%IPREL Non-Call Branch

This metric provides the percentage of IPREL non-call branches among all branches.

232 Event Set Descriptions for CPU Metrics