Looking at the per-line call counts only tells part of the story.
gprof can only report call times and counts by function,
the best way to get finer-grained information on where the program
is spending its time is to re-factor large functions into sequences
of calls to smaller ones. Beware however that this can introduce
artificial hot spots since compiling with ‘-pg’ adds a significant
overhead to function calls. An alternative solution is to use a
non-intrusive profiler, e.g. oprofile.
Use ‘gprof -l’ and lookup the function in the call graph. The callers will be broken down by function and line number.
Try using a shell script like this one:
for i in `seq 1 100`; do fastprog mv gmon.out gmon.out.$i done gprof -s fastprog gmon.out.* gprof fastprog gmon.sum
If your program is completely deterministic, all the call counts will be simple multiples of 100 (i.e., a function called once in each run will appear with a call count of 100).