HP UX IPFilter Software Branch Measurement Report Description, How Alat Metrics Are Obtained

Table 9 Information in alat Measurement Reports (continued)

Column	Description
	Column and line numbers are preceded by “~” when they are approximate due to
	optimization.
>Statement	The column contains either a source statement, preceded by “>”, or a disassembled instruction.
Instruction	Statements that are out of order due to optimization are preceded by “*>”.

How ALAT Metrics Are Obtained

HP Caliper obtains ALAT metrics from the processor's performance monitoring unit (PMU).

Exact counts are obtained from the PMU's set of performance monitor configuration (PMC)/performance monitor data (PMD) register pairs. Sampled ALAT metrics are obtained from the PMU's data event address register (D-EAR).

HP Caliper takes samples every Nth recorded ALAT miss, where N is defined in the alat measurement configuration file in the HP Caliper home directory config subdirectory. At each sample point, HP Caliper records the instruction that resulted in an ALAT miss. You can override the value in the measurement configuration file by using the -soption.

More frequent sampling increases HP Caliper's perturbation of your application. In particular, taking a sample could cause some of the ALAT content to be replaced. If so, the following chk.a/ld.c instructions are more likely to fail, making the resulting data of limited value.

branch Measurement Report Description

With the branch measurement, produced by the branch measurement configuration file, HP Caliper measures and reports two levels of information:

•Exact counts of branch prediction metrics summed across the entire run of an application

•Sampled branch prediction metrics that are associated with particular locations in the application

The report shows measured data by thread, load module, function, statement, instruction bundle, and instruction.

Command-line options allow you to control the amount of data reported, how the data are sorted, and the number of statements and instructions reported for each sampled program location.

Example Command Line for Text Report

$ caliper branch -o brp.txt ./wordplay thequickbrownfox

Example Command Line for CSV Report

$ caliper branch --csv csvout ./wordplay thequickbrownfox

branch Metrics Summed for Entire Run

This section describes the metrics summed over the entire run of your application under HP Caliper.

Metrics for Integrity Servers Itanium 2 Systems

•BR_MISPRED_DETAIL.ALL.CORRECT_PRED

Number of branch predictions that did not require a back-end branch misprediction flush, independent of predictor. A mismatch between the predicted and actual values of the branch predicate or target results in a branch misprediction. Return branches must additionally predict privilege level and previous function state.

•BR_MISPRED_DETAIL.ALL.WRONG_PATH

Number of branch mispredictions that resulted from a mismatch of the predicted and actual values of the branch predicate, independent of predictor.

branch Measurement Report Description 175