By default TAU profiles the total time (inclusive/exclusive) spent on a
given function. Profiling each function call
for an application that calls some function hundred of thousands of
times, is impractical since the profile data would grow enormously. But
configuring TAU with the -PROFILEPARAM
option will have
TAU profile select functions
each time they are called. But TAU will also
group some of these function calls together according to the value of
the parameter they are given. For example if a function mpisend(int i) is called 2000
times 1000 times with 512 and 1000 times with 1024 then we will receive two
profile for mpisend() one we it is called with 512 and one when it is called with
1024. This reduces the overhead since we are profiling mpisend() two times not 2000
times.