Using Valgrind for performance profiling

[Ian Monroe]

On Sat, Oct 25, 2008 at 9:22 AM, Andreas Mützel <andreas.muetzel at gmx.net> wrote:
> 2008-10-22 Mark Kretschmann:
>> For instance it could be interesting to see where we spend most of the
>> time during startup and shutdown.
>
> I just finished a few tests, i didn't notice any real problem. I profiled 3
> situations (startup, normal playback, shutdown), these are the results:
>
> startup:
> - about 60% of the time is spent in QLibraryPrivate::isPlugin, which seems to
> be indirectly called by the qtscript engine on startup
> (AmarokScript::ScriptImporter::loadQtBinding calls
> QScriptEngine::importExtension which then cally some qt internal stuff which
> calls QLibraryPrivate::isPlugin)
> - the rest seems ok
>
> normal playback:
> - nothing to see here, almost all time is spent in phonon (as expected)
>
> shutdown:
> - no problems, most of the time is spent in destructors or in free(), i can't
> see any expensive operations going on.
>
> If you want to have a look at the callgraphs etc.: I'm oploading the callgrind
> output of the startup and shutdown right now, you'll be able to find them
> here:
> http://www.uni-koblenz.de/~amuetzel/callgrind.out.startup
> http://www.uni-koblenz.de/~amuetzel/callgrind.out.shutdown
> (You'll need kcachegrind to view them.)
>
> As I couldn't find any important performance issues, I'll do some checks for
> memory leaks with valgrind.

Qt 4.5 promises much improvements in regards to qtscript binding load
times. So while the load times do seriously suck now, its just a
temporary thing.

Thanks for your valgrinding. :)

Ian