[maemo-developers] gprof-base Profiling: "no time accumulated"

[From: Thomas Thrainer]

Am Samstag 24 Januar 2009 schrieb Siarhei Siamashka:
> On Saturday 24 January 2009, Thomas Thrainer wrote:
> > Hello,
> >
> > I'm trying to profile an application on the N810 with gprof. I compiled
> > it with -pg, -O3  and -g and linked all the libraries I'm interested in
> > statically (and compiled them also with -pg -O3 -g).
> >
> > The first couple of problems were that I got a floating point exception
> > in scratchbox when starting the program, and a crash on the tablet. Using
> > -fno- unit-at-a-time and -fno-omit-frame-pointer solves the problem on
> > the tablet, it still doesn't run in scratchbox tough. By the way, this is
> > related to -O3, non-optimized build run fine in both scratchbox and on
> > the tablet.
> >
> > My problem is however, that profiling doesn't give any usable results. In
> > the profile written to gmon.out there are all times 0.0. But the call
> > graph and calling count for functions is correct.
> >
> > I tried to strace the application, and profiling seems to work normally.
> > The profiling code sets up the profiling timer, and the SIGPROF signal is
> > received regularly throughout the program run.
> > So I suspect the profiling code, or more precisely the SIGPROF-handler,
> > to not being able to get the currently executing function based on the
> > stack. My program is not spending a lot of time in some library functions
> > or such, most of the time it's usually in some user-functions (I know
> > that based on profiling on my PC).
> >
> > Can anybody shed some light on this issue? To I have to link against some
> > special version of glibc? Or is profiling with gprof broken on ARM's?
>
> IIRC, there might be something wrong with the toolchain in the respect of
> support for -pg option.
>
> On the other hand, do you really need to use gprof? Profiling on N810 can
> be done with oprofile, which covers all the gprof functionality and
> provides a lot more features. Please check the following page:
> http://maemo.org/development/tools/doc/diablo/oprofile/
>
> If you think that for your specific case gprof is better and doubt that
> oprofile can handle it well, please describe what exactly you want to do.
> I'll try to advice something.

I tried oprofile, and it worked nicely for me. I actually wanted to use gprof 
because I used it on my development machine too and I wanted to use the same 
tool in order to get comparable results.
But anyway, now I have my profiling results, so thanks for the tip.