Re: Profiling GNAT programs with gprof

[Jeff Creem <jcreem@yahoo.com>]

Jean-Pierre Rosen wrote:
> Marius Amado Alves a �crit :
> 
>> I also have experienced erroneous Gprof results. Functions *never* 
>> called listed as called. I gave up on Gprof. Sorry not being of help. 
>> Just telling my experience. Next time I need profiling I think I'll 
>> try another tool e.g. RootCause, or instrument my code. Good luck to 
>> you with Gprof.
>>
> I had obviously wrong results with gprof both with tasking and 
> non-tasking programs, and I gave up using it.
> 
> <PLUG>
> Note that if you just want to time some procedure calls (not full 
> profiling), you can use the facilities from Debug.Timing package, 
> available as part of Adalog's Debug package.
> See http://www.adalog.fr/compo2.htm
> </PLUG>
> 

I have had good luck with gprof on non-tasking programs though in most 
cases I ended up either having to increase the systems default interrupt 
clock rate to get good results or wrapping the main code I cared about 
in a loop to get good results (this was needed even for non-trival 
programs that were not all that fast to complete).

Also to get reasonable results I often have to revert to using the -F 
option (better when possible) or a series of -f options (still ok but 
not great when -F is really neeeded)

As for tasking programs...There is a lot of info on the web about gprof 
failing with threads/forks/etc and a few platform specific workarounds 
appear to exist.

The failure mechanisms also seem somewhat platform specific as well.

http://sam.zoy.org/writings/programming/gprof.html