Re: Scrolling performance

["Clemens Eisserer" <linuxhippy gmail com>]

Hi Roo,

Just a side note: GTK-2.9.4 built with "-O2 -g -fPIC" is a lot slower
than the stuff shipped with OpenSuSE (I guess 2.8.6+). maybe the
debugging symbols cause cache misses ... I don't know but its about
25-75% slower.

> Right... so the GTK developers left normal users without the ability to
> compare it directly. That makes a lot of sense if they wanted to find out
> the real facts and figures behind Cairo...
Well Cairo is used for many operations since GTK-2.8.
I suggest to use oprofile which is really a great tool for a qucik
overview where time is spent, however for call-graphs and other more
complex information its not provided

> Even with gtk-perf I'm still stuck being unable to make a comparison,
> since they took away that option.
Sorry I don't understand what you mean.

GtkPerf isn't really suited for a number/number comparison, however
its not that bad to get hints whats going on. Keep in mind that some
open windows larger than the root-window -> infalidate other windows.
I recommend maximizing gtkperfs window before testing.

> I don't think that's acceptable at all. Cairo pretty obviously has major
> performance problems (even if you accept that it is only on some cards),
> and the GTK developers forced everyone to use it without even a fallback.
Where do you know that cairo is the problem?
I've seen some difffernt situations from oprofile. Sometimes Cairo is
really a problem (e.g. the focus-dotted lines of buttons seem to be
rendered in software and when painting this button is the hotspot
cairo consumes 50% cpu), but most time cairo adds "just" an 5-10%
overhead which should become better from time to time (I hope so).

As you maybe've heard I'll start tuning backbuffer stuff very soon
(prototype shows 35% better gtkperf on my system, some tests are 10x
faster - but is far away from uefulness).
This will maybe solve some problems, but some problems still persist
(moving other windows over trees, lists, tables or resizing them is
still horrible).
Maybe you could fire up your profiler and help a bit, the sooner more
people work on performance the sooner we'll see better results.
Especially the widget tuning stuff is something I don't know much
about.

lg Clemens