Instrumentation for Call Graph Profiling

Instrumentation is the process of modifying a program so that dynamic information is recorded during program execution. Data collection routines invoked at specific points in the execution of the target program record run-time information. These routines provide information about time spent in each function, and the call sequence that leads to a specific function. By default, the VTune(TM) Performance Analyzer instruments all application functions and system-level exports.

This process does not change the functionality of the program. However, during runtime, it slows performance down.

The VTune analyzer keeps track of the exit and entry points, records the number of times each function was called, establishes a relationship between the caller (parent) and callee (child) function, and stores this data.

The VTune analyzer automatically starts instrumentation of the selected module when you run the Activity. The VTune analyzer keeps instrumented files in the cache directory and uses them for the call graph data collection when you run the Activity.

Use the Call Graph: Collector preferences and Configure Call Graph dialog box to configure the following instrumentation settings:

• instrumentation level

• call graph buffer size

Use the Function Selection dialog box to select functions to instrument in a particular module.

To change the default instrumentation settings in the command-line interface (vtl), edit the collector configuration files generated upon creating an Activity.