Using callgrind to find out which functions are most intensive

Question

I have just used callgrind on a file and it gave me a callgrind output. Then I used callgrind_annotate to get the results in a more readable form, and I output it into a text file. How am I supposed to decipher this new file to find out which functions are the most intensive? What is the Ir column on the left? What does Ir stand for?

Answer 1

Ir stands for 'instructions read' IIRC.

I recommend kcachegrind, instead, a nice graphical tool that immediately shows everything you need to know.