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
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
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