Chapter 3. Tracing

Table of Contents

3.1. Generating Event Traces

Typically, profiling shows the distribution of execution time across routines. It can show the code locations associated with specific bottlenecks, but it can not show the temporal aspect of performance variations. Tracing the execution of a parallel program shows when and where an event occurred, in terms of the process that executed it and the location in the source code. This chapter discusses how TAU can be used to generate event traces.

3.1. Generating Event Traces

To enable tracing with TAU, set the environment variable TAU_TRACE to 1. Similarly you can enable/disable profile with the TAU_PROFILE variable. Just like with profiling, you can set the output directory with a environment variable:

% setenv TRACEDIR /users/sameer/tracedata/experiment56

This will generate a trace file and an event file for each processor. To merge these files, use the script. If you want to convert TAU trace file into another format use the tau2otf, tau2vtf, or tau2slog2 scripts.