Table 34 Information in traps Measurement Reports (continued)

Column

Description

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 traps Metrics Are Obtained

HP Caliper obtains traps metrics using the execution trace buffer (ETB) of the performance monitoring unit (PMU). The ETB is configured to capture all changes to/from privilege level 0.

HP Caliper takes samples by using the overflow of one of the PMU's event counters as a sampling trigger. Samples are taken every Nth PMU event, where both N and the sampling event are defined in the traps measurement configuration file in the HP Caliper home directory in the config subdirectory. You can override the value in the measurement configuration file by using the -soption.

HP Caliper attributes a sample to a trap by checking which offset into the interruption vector table (IVT) the target branches to. HP Caliper gets the IVT start address from perfmon on HP-UX and by reading kallsyms on Linux.

218 Descriptions of Measurement Reports