mutrace and tiles3

[Boudewijn Rempt]

On Wed, 16 Sep 2009, Thomas Zander wrote:

> On Wednesday 16. September 2009 10.51.38 Cyrille Berger wrote:
> > On Wednesday 16 September 2009, Boudewijn Rempt wrote:
> > > I did exactly the same thing as with tiles1. It was much slower -- and
> > > the results are certainly puzzling, since the main contention doesn't
> > > seem to come from the tile engine!
> >
> > I wouldn't be so sure, since 190168 is a mutex used by the event loop, if
> > tiles3 use more signals it can be the explanation.
> 
> I've seen some applications crawl because they generate too many events. The 
> Qt event queue then ends up being an overhead thats too great.  Things like 
> timers are guilty of that and, like Cyrille said, signals among various 
> other things.
> It might be fun to check the amount of events that are executed on the event 
> loop per second coming from Krita vs from X11.
> See QCoreApplication::setEventFilter()

Hm, yes, that would be interesting. Especially since we use signals/slots between
threads for instance for recompositing and progress reporting, and those are events,
too. Only -- that is not a difference between the two tiles engines, and since that's
the only difference in my test, I'm still puzzled.

But I'll investigate that lead, too, it's an excellent idea.

Boudewijn