HP XC System 3.x Software - Manual (Page 64)

Multiple Labels
An event can be recorded in only one data set, that is, one label. If you have multiple labels
defined and a process matches the selectors for more than one label, the events for that process
are recorded in only one data set, and that data set is indeterminate.
Reusing Labels
You can specify the same label name in multiple hpcpictl commands. Each instance of the
hpcpictl label
command creates a separate data set, and HPCPI aggregates all data sets
with the same specified label name and within the same epoch. For example, the user enters the
following commands:
% hpcpictl label mylabel myApp one
% hpcpictl label mylabel myApp two
% hpcpictl label mylabel myOtherApp bbb
You can specify the label mylabel as an option (-label mylabel) for HPCPI analysis tools
to select the performance data for all three processes.
The maximum number of concurrent data sets is 16.
Comparing Epochs and Labels
An epoch is a time-based boundary in the HPCPI database. An epoch does not isolate data
according to process ID or any other process characteristics.
The following is an example of a user session using epochs to isolate performance data for code
executed from libc-2.3.4.so by myApp:
% hpcpictl epoch
% myApp
% hpcpictl epoch
% hpcpiprof -epoch latest-1 libc-2.3.4.so
One disadvantage of using epochs only is that you cannot isolate events from shared images
executed from the user application. In this session, the command hpcpiprof -epoch latest-1
libc-2.3.4.so
reports statistics for all code executed from the libc-2.3.4.so library during
the execution of myApp, which may include data for libc-2.3.4.so code executed by processes
other than the myApp process.
By comparison, the following is an example of a user session using labels to isolate performance
data for myApp:
% hpcpictl label myLabel myApp
% hpcpictl flush
% hpcpiprof -label myLabel libc-2.3.4.so
The command hpcpiprof -label myLabel libc-2.3.4.so reports statistics only for
libc-2.3.4.so
code executed by the myApp process, unlike the hpcpiprof -epoch
latest-1 libc-2.3.4.so command in the previous example.
Using Epochs with Labels
You can use epochs with labels. If you have a label established and start another epoch, the labels
are retained across epochs (the label remains active until the command executed by the hpcpictl
utility completes).
NOTE: HP would like to know if you use labels and epochs concurrently to partition data. If
you do, contact HP using the email address in the HPCPI and Xtools Release Notes.
64 Using HPCPI Labels