KCachegrind is a helpful at a late stage in software development, called profiling. If you don't develop applications, you don't need KCachegrind.

These are cost attributes for functions regarding some event type. As functions can call each other, it makes sense to distinguish the cost of the function itself (“Self Cost”) and the cost including all called functions (“Inclusive Cost”). “Self” is sometimes also referred to as “Exclusive” costs.

So, for example, for main(), you will always have an inclusive cost of almost 100%, whereas the self cost is negligible when the real work is done in another function.

KCachegrind has probably been installed incorrectly on your system. It is recommended to compile it with the installation prefix set to your system-wide KDE base folder, like configure --prefix=/opt/kde4; make install. If you choose another folder, like $HOME/kde, you should set the environment variable KDEDIR to this folder before running KCachegrind.

You have activated a function below main(), which obviously costs less than main() itself. For every function, it is shown only the part of the cost spent while the activated function is running; that is, the cost shown for any function can never be higher than the cost of the activated function.