[Qt-creator] Very slow GDB when stepping into functions

[Peter Kümmel]

Am Donnerstag, den 04.02.2010, 19:19 +0100 schrieb Andre Poenitz:
> On Thu, Feb 04, 2010 at 06:36:21PM +0100, Peter Kümmel wrote:
> > Maybe someone also wonders why stepping into a function
> > takes several tens of seconds at 100% CPU usage of gdb.
> > Here's the answer for Debian based systems: 
> > 
> > "Debugging symbols for ld.so are not shipped"
> > http://blogs.gnome.org/jjongsma/2007/01/08/gdb-slowness/
> > 
> > Therefore this:
> >    sudo apt-get install libc6-dbg
> > solves the problems on my Ubuntu machine.
> > 
> > Could someone please update the QtCreator Wiki:
> > http://qt.gitorious.org/qt-creator/pages/FrequentlyAskedQuestions#Debugger
> 
> That's interesting as I recently looked into a similar problem and
> tracked it down to the use of the wrong algorithm for symbol lookup, see
> http://sourceware.org/bugzilla/show_bug.cgi?id=11198 .
> 
> This particular issue has been fixed in the mean time in gdb.
> 
> I wonder whether our problems are related, and if so, how such
> completely different solutions can be possible.
> 
> Could you do me a favour and check whether uninstalling the libc6-dbg
> package and using a recent gdb from CVS also fixes your problem?

Yes, cvs version it about 10 times faster, with no libc6-dbg
installed.

Daniel's gdb 7.0.1 from ppa.launchpad.net/daniel-molkentin/gdb/ubuntu
took 17s to step into QCoreApplication and 40s into a custom ctor.

After using the cvs version (34edd79074a60f5eb6) from the git mirror
it's about 10 times faster!
17s -> ~1.8s
40s -> 4s

I've only changed the path to gdb in qtcreator and tried again 
without restarting.

When I reinstall libc6-dbg, gdb 7.0.1 enters both ctors nearly
immediately but the cvs version times don't change.


Peter