HP Caliper User's Guide

Table B-2 Information in branch Measurement Reports (continued)
DescriptionColumn
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 branch Metrics Are Obtained
HP Caliper obtains branch 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 branch prediction
metrics are obtained from the PMU's branch trace buffer (BTB)/execution trace buffer
(ETB).
HP Caliper takes samples every Nth branch event, where N is defined in the branch
measurement configuration file in the HP Caliper home directory config subdirectory.
At each sample point, HP Caliper records branch metrics from the BTB/ETB. You can
override the value in the measurement configuration file by using the -s option.
HP Caliper reports each branch prediction metric at the lowest granularity available
from the BTB/ETB. The branch direction outcome and branch prediction information
is available at the granularity of each of the four possible branch ways (taking the
branch in slot 0, slot 1, or slot 2, or falling through to the next bundle). The property of
being a branch target is only relevant at the granularity of a bundle.
branch Measurement Report Description 231