Collecting trace information

There are three ways to collect trace information. You can use:

• The Profiling tab on the System Options dialog box

• A window similar to the Profiling tab

• Trace objects and functions

Whichever method you use, you can specify:

• The name and location of the trace file and optional labels for blocks of trace data

• The kind of timer used in the trace file

• The activities you want recorded in the trace file

The default name of the trace file is the name of the application with the extension PBP. The trace file is saved in the directory where the PBL or executable file resides and overwrites any existing file of the same name. If you run several different tests on the same application, you should change the trace file name for each test.

You can also associate a label with the trace data. If you are tracing several different parts of an application in a single test run, you can associate a different label with the trace data (the trace block) for each part of the application.

There are three kinds of timer: clock, process, and thread. If your analysis does not require timing information, you can omit timing information from the trace file to improve performance.

If you do not specify a timer kind, the time at which each activity begins and ends is recorded using the clock timer, which measures an absolute time with reference to an external activity, such as the computer’s start-up time. The clock timer measures time in microseconds. Depending on the speed of your computer's central processing unit, the clock timer can offer a resolution of less than one microsecond. A timer’s resolution is the smallest unit of time the timer can measure.

You can also use process or thread timers, which measure time in microseconds with reference to when the process or thread being executed started. You should always use the thread timer for distributed applications. Both process and thread timers exclude the time taken by any other running processes or threads so that they give you a more accurate measurement of how long the process or thread is taking to execute, but both have a lower resolution than the clock timer.

You can choose to record in the trace file the time at which any of the following activities occurs. If you are using the System Options dialog box or a window, you select the check boxes for the activities you want. If you are using PowerScript functions to collect trace information, you use the TraceActivity enumerated type to identify the activity.

When you begin and end tracing, an activity of type ActBegin! is automatically recorded in the trace file. User-defined activities, which you use to log informational messages to the trace file, are the only trace activities enabled by default.