B Descriptions of Measurement Reports

This appendix contains descriptions of reports produced for each HP Caliper measurement. It shows example command lines you can use to produce the reports and describes the data available with the measurements.

NOTE: The information provided in this appendix for each report description is a subset of the 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 measurement

For more information (some of which you receive when you use the --infooption or the caliper info command), see “Controlling the Content of Reports” (p. 105). In particular, see these topics:

•“Function Details” (page 111)

•“Disassembly Listing” (page 111)

•“Source Position Correlation” (page 112)

•“Address Types Shown” (page 112)

•“Unnamed Functions” (page 113)

•“Unknown Functions” (page 113)

alat Measurement Report Description

With the alat measurement, produced by the alat measurement configuration file, HP Caliper measures and reports advance load address table (ALAT) misses.

The ALAT keeps track of speculative (that is, advance) loads. An excessive number of ALAT compares that result in a failed advance load (an ALAT miss) can seriously degrade performance. ALAT misses might point to inefficient use of data speculation in assembly-level code or code generated by a compiler or virtual machine.

A miss ratio higher than 10 percent suggests a problem with how the program uses data speculation. The report shows two levels of information:

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

•Sampled failed ALAT check instructions (chk.a or ld.c) that are associated with particular locations in the measured application.

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

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

To improve your results, try the following:

•When compiling from high-level code, change compiler options that affect data speculation.

•When writing assembly code, tune the source code in the hot spots shown in the report.

•When writing a compiler or a virtual machine, tune the code generator.

Example Command Line for Text Report

$ caliper alat -o reports/alat.txt ./wordplay thequickbrownfox

Example Command Line for CSV Report

$ caliper alat --csv csvout ./wordplay thequickbrownfox

alat Metrics Summed for Entire Run

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

alat Measurement Report Description 171