How did I to know the time cost of each function in wireshark?

How did I to know the time cost of each function in wireshark? and then I can debug the which function have take so long time when wireshark running.

1,In linux ,I want to use gprof to detect the function. So I change the makefile:add -pg to compile and link process.but it is not work.I can't get the gmon.out.

2,In XP,I use vs2010 performance profile to detect.after I finish all step ,then come some error:the *.vsp have no data.

How can I find the function? Thanks!