Table of Contents
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.
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 tau_treemerge.pl script. If you
want to convert TAU trace file into another format use the
tau2otf, tau2vtf, or
tau2slog2 scripts.