HP Caliper User's Guide

Table B-1 Information in alat Measurement Reports (continued)
DescriptionColumn
Routine from your application.Function
Source file associated with a function.File
The column contains one of these:
• A source-code line number for rows showing statements
• 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.
Line |
Slot |
Col,Offset
The column contains either a source statement, preceded by “>”, or a disassembled
instruction. Statements that are out of order due to optimization are preceded by
“*>”.
>Statement |
Instruction
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 -s option.
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.
226 Descriptions of Measurement Reports