HP Caliper User Guide Release 5.5 (5900-2351, August 2012)

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 -s
option.
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.
traps Measurement Report Description 229