Speed of Krita 2.4

[Boudewijn Rempt]

On Saturday 30 July 2011 Jul, Dmitry Kazakov wrote:
> > > PS: as an example of slowness: for small brushes, in Krita 2.3 I trace a
> > > line of any width and it appears on the screen instantaneously, in 2.4 I
> > > trace a line 5px wide and it appears on the screen approximately 1 second
> > > later per 400 px of total line length.
> >
> 
> Hi! Usually, valgrind is a good tool for searching for bottlenecks. For
> small brushes, there might be several reasons for a slowdown:
> 
> 1) Recently, we activated a new setDirty(QVector<QRect>) signals, so it
> might be a reason. To check this you can edit KisPainter::takeDIrtyRegion()
> to return a united rect instead. But you'll need some stable method of
> measurement for this.

That could indeed be a candidate. It replaced a patch where we used QRegion which definitely caused a slowdown. Using the unified rect, however, slows down mirrored and two-handed painting badly. We could probably make this conditional if it's really the problem.

> 
> 2) I had such problem when I forgot to disable assert checks and tested
> Dedug build =). RelWithDebInfo should be ok, I guess (Cyrille will correct
> me if i'm wrong =) )

KritaDevs should be good: it has asserts, debug symbols and optimizations. There's a huge difference between unoptimized and optimized builds.

> 
> 
> You can measure the brush painting speed with the stroke benchmarks. But if
> they show the same results, then the problem might be in some update code.
> Then you can try the following.
> Recently, I've worked on a class for measurement the brush resposiveness. It
> measures the time when the painting and update (in the scheduler) are
> finished. You can use this class for comparison of different versions as
> well. And you can extend it to measure scaling in the KisPrescaledProjection
> as well. The class is called KisUpdateTimeMonitor and it is placed in a
> branch response-measure-old-kazakov. But this class doesn't give you the
> 'avarage speed', it gives you a graph response_time=f(mouse_speed). Like
> this [1].
> 
> 
> [1] -
> http://s677.photobucket.com/albums/vv137/dimula73/?action=view&current=krita_graph2.png
> 
> 


-- 
Boudewijn Rempt
http://www.valdyas.org, http://www.krita.org, http://www.boudewijnrempt.nl