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

Table 9 Information in alat Measurement Reports (continued)
DescriptionColumn
Column and line numbers are preceded by “~” when they are approximate due to
optimization.
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.
branch Measurement Report Description
With the branch measurement, produced by the branch measurement configuration file, HP
Caliper measures and reports two levels of information:
• Exact counts of branch prediction metrics summed across the entire run of an application
• Sampled branch prediction metrics that are associated with particular locations in the
application
The report shows measured data by thread, load module, function, statement, instruction bundle,
and instruction.
Command-line options allow you to control the amount of data reported, how the data are sorted,
and the number of statements and instructions reported for each sampled program location.
Example Command Line for Text Report
$ caliper branch -o brp.txt ./wordplay thequickbrownfox
Example Command Line for CSV Report
$ caliper branch --csv csvout ./wordplay thequickbrownfox
branch Metrics Summed for Entire Run
This section describes the metrics summed over the entire run of your application under HP Caliper.
Metrics for Integrity Servers Itanium 2 Systems
• BR_MISPRED_DETAIL.ALL.CORRECT_PRED
Number of branch predictions that did not require a back-end branch misprediction flush,
independent of predictor. A mismatch between the predicted and actual values of the branch
predicate or target results in a branch misprediction. Return branches must additionally predict
privilege level and previous function state.
• BR_MISPRED_DETAIL.ALL.WRONG_PATH
Number of branch mispredictions that resulted from a mismatch of the predicted and actual
values of the branch predicate, independent of predictor.
branch Measurement Report Description 173