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

Table 9 Information in alat Measurement Reports

Column	Description
% Total Sampled ALAT	Percent of the total for <metric> attributable to a given program object. The <metric> is the
Misses	same as the <metric> HP Caliper uses for sorting, except when the sort metric is address,
	in which case sampled misses is used.
Cumulat % of Total	A running sum of the percent of total for <metric> accounted for by the given program object
	and those listed above it.
Sampled ALAT Misses	Total number of sampled failed chk.a/ld.c instructions attributed to the given program
	object.
Kernel Thread	Kernel Thread ID suffixed with the the name of the routine that the thread will execute once
Identification Number	it is created.
Load Module	A shared library or the main executable.
Function	Routine from your application.
File	Source file associated with a function.
Line	The column contains one of these:
Slot	• A source-code line number for rows showing statements
Col,Offset
	• An instruction slot number for rows showing instructions not on a bundle boundary
	• A source-code column number followed by an offset from the beginning address of a
	function for rows showing instructions on a bundle boundary
	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.

branch Measurement Report Description 171