Where the Data Is Stored

The data collected during one execution of your application is called an experiment. The experiment consists of a set of files that are stored in a directory. The name of the experiment is the name of the directory.

In addition to recording the experiment data, the Collector creates its own archives of the load objects used by the program. These archives contain the addresses, sizes and names of each object file and each function in the load object, as well as the address of the load object and a time stamp for its last modification.

Experiments are stored by default in the current directory. If this directory is on a networked file system, storing the data takes longer than on a local file system, and can distort the performance data. You should always try to record experiments on a local file system if possible. You can specify the storage location when you run the Collector.

Experiments for descendant processes are stored inside the experiment for the founder process.

Experiment Names

The default name for a new experiment is test.1.er . The suffix .er is mandatory: if you give a name that does not have it, an error message is displayed and the name is not accepted.

If you choose a name with the format experiment.n.er, where n is a positive integer, the Collector automatically increments n by one in the names of subsequent experiments. For example, mytest.1.er is followed by mytest.2.er, mytest.3.er , and so on. The Collector also increments n if the experiment already exists, and continues to increment n until it finds an experiment name that is not in use. If the experiment name does not contain n and the experiment exists, the Collector prints an error message.

Experiments can be collected into groups. The group is defined in an experiment group file, which is stored by default in the current directory. The experiment group file is a plain text file with a special header line and an experiment name on each subsequent line. The default name for an experiment group file is test.erg. If the name does not end in .erg, an error is displayed and the name is not accepted. Once you have created an experiment group, any experiments you run with that group name are added to the group.

You can manually create an experiment group file by creating a plain text file whose first line is

#analyzer experiment group

and adding the names of the experiments on subsequent lines. The name of the file must end in .erg.

You can also create an experiment group by using the -g argument to the collect command.

Experiments for descendant processes are named with their lineage as follows. To form the experiment name for a descendant process, an underscore, a code letter and a number are added to the stem of its creator’s experiment name. The code letter is f for a fork, x for an exec, and c for combination. The number is the index of the fork or exec (whether successful or not). For example, if the experiment name for the founder process is test.1.er, the experiment for the child process created by the third call to fork is test.1.er/_f3.er . If that child process calls exec successfully, the experiment name for the new descendant process is test.1.er/_f3_x1.er .

Moving Experiments

If you want to move an experiment to another computer to analyze it, you should be aware of the dependencies of the analysis on the operating environment in which the experiment was recorded.

The archive files contain all the information necessary to compute metrics at the function level and to display the timeline. However, if you want to see annotated source code or annotated disassembly code, you must have access to versions of the load objects or source files that are identical to the ones used when the experiment was recorded.

The Performance Analyzer searches for the source, object and executable files in the following locations in turn, and stops when it finds a file of the correct basename:

• The archive directories of experiments.

• The current working directory.

• The absolute pathname as recorded in the executables or compilation objects.

You can change the search order or add other search directories from the Analyzer GUI or by using the setpath (see setpath path_list) and addpath ( see addpath path_list) directives. You can also augment the search with the pathmap command.

To ensure that you see the correct annotated source code and annotated disassembly code for your program, you can copy the source code, the object files and the executable into the experiment before you move or copy the experiment. If you don’t want to copy the object files, you can link your program with -xs to ensure that the information on source lines and file locations are inserted into the executable. You can automatically copy the load objects into the experiment using the -A copy option of the collect command or the dbx collector archive command.