I just started to use OProfile for profiling and it's an awesome tool!

I used sampling a lot and was trying to apply call-graph patch, however I only get a very general description from the OProfile website for this patch:
" This patch provides support for call-graph profiling, currently only on x86. At each interrupt, the stack is recorded into the profile buffer, if the information is available in the registers. The user-space support for this, new in the 0.8 release, is still experimental."

I don't have much clue on how to do that. It would be extremely helpful if someone can give a procedure list on how to apply the call-graph patch. Thanks a lot,