HP XC System 3.x Software - Manual (Page 56)

Limiting the Event Count Display (hpcpiprof -keep Option)
If you have a lot of data, you can use the -keep option with hpcpiprof to limit the number of
event counts it displays. For example:
% hpcpiprof -keep 99
Using Database Directories, Epochs, or Labels to Organize Your Data
You can use different HPCPI database directories, epochs, or labels to organize performance
data from different applications or instances of an application.
Database Directories
To use a different database directory, you must stop and restart the daemon. You can specify
the database directory name using the -db option when starting the daemon and when running
the analysis tools. You can assign names to the directories that are meaningful to you.
For more information, see “Selecting a Location for the HPCPI Database Directory” (page 36)
and “Specifying an Alternate Database” (page 51) .
Epochs
To start a new epoch, use the hpcpictl epoch command. When you use epochs, you do not
need to stop and restart the daemon. Another advantage is that labels are retained across epochs.
However, epoch names are not user configurable and are based on the time an epoch is started.
You might have problems remembering the application or activities that correlate to an epoch.
You can create a symbolic link with a meaningful name to an epoch directory, but this is an
additional task.
For more information, see “Starting a New Data Epoch: hpcpictl epoch” (page 41) and
“Specifying an Alternate Epoch” (page 51) .
Labels
To create a label, use the hpcpictl label command. When you use labels, you do not need
to stop and restart the daemon. The HPCPI label mechanism enables you to partition data using
multiple parameters. Labels are a more flexible method to partition and notate performance data
than epochs.
For more information on using labels, see Chapter 5 (page 59) .
Event Intervals
HP recommends that you do not use sampling intervals that are lower than the default values
when using non-Itanium processors.
Non-Itanium processors do not freeze event monitoring when an interrupt occurs to handle
event recording for the PMU. This causes events related to handling event recording to leak and
be attributed to images other than the interrupt handler. Decreasing the HPCPI sampling interval
(increasing the sampling frequency) increases this leakage.
Multiple Duty Groups
If you monitor more events than the number of event counters supported by the processor,
HPCPI cannot monitor all events at the same time. HPCPI places the events in duty groups and
multiplexes (cycles through) the duty groups so that the PMU only counts the events in one duty
group at a time (the active group). This multiplexing increases the leakage described in
“Event
Intervals” (page 56) . On non-Itanium processors, HP recommends that you do not use data
collected with multiple duty groups for fine-grained analysis.
56 Using HPCPI