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List:       kde-panel-devel
Subject:    Re: Review Request: Analog clock painting performance
From:       "Alain Boyer" <alainboyer () gmail ! com>
Date:       2008-11-30 18:35:09
Message-ID: 20081130183509.5139.86410 () vidsolbach ! de
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> On 2008-11-30 09:01:20, Aaron Seigo wrote:
> > hm. that seems a little suspect to me, but if grabbing the cached rects is really \
> > that slow, then Theme::findInRectsCache is probably what needs to be optimized. 
> > can you post the cachegrind output somewhere, along with the clock configuration \
> > you used? 
> > 

It's not that it is very slow, it's that it was called 13 times for each update. \
Quite a bit of overhead when you have the m_fancyHands enabled!

http://aboyer.dyndns.org/kde/callgrind.out.before
http://aboyer.dyndns.org/kde/callgrind.out.after

> From the comments below, I guess the moral of the story is not to assume that the \
> elements are properly positioned in the svg file. These changes now become pretty \
> useless. I'll try to reduce the amount of actual painting instead of caching the \
> rects.


> On 2008-11-30 09:01:20, Aaron Seigo wrote:
> > /trunk/KDE/kdebase/workspace/plasma/applets/analog-clock/clock.cpp, line 317
> > <http://reviewboard.vidsolbach.de/r/290/diff/1/?file=1565#file1565line317>
> > 
> > are you sure about that?

Actually, this is the one change that I'm pretty sure about! :) It ensures that the \
second hand is properly aligned with the clock face markers.

The "seconds" variable is computed at each update. This makes it overshoot by 1 \
degree and then return to the precise position instead of undershooting by 1 degree.


- Alain


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On 2008-11-30 07:32:56, Alain Boyer wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://reviewboard.vidsolbach.de/r/290/
> -----------------------------------------------------------
> 
> (Updated 2008-11-30 07:32:56)
> 
> 
> Review request for Plasma.
> 
> 
> Summary
> -------
> 
> This patch attempts to speed up the analog clock painting performance. Essentially, \
> it caches the QRects of the theme elements and streamlines some of the painting \
> code. 
> The speedup is explained below, however I think we can do even better. For example, \
> we could draw the hour and minute hands and shadows to a pixmap and then use that \
> when only the second hand needs an update. I'm not sure if this is the way to go? \
> Comments or suggestions? 
> 
> Diffs
> -----
> 
> /trunk/KDE/kdebase/workspace/plasma/applets/analog-clock/clock.h
> /trunk/KDE/kdebase/workspace/plasma/applets/analog-clock/clock.cpp
> 
> Diff: http://reviewboard.vidsolbach.de/r/290/diff
> 
> 
> Testing
> -------
> 
> Valgrind tells me that this patch introduces a 1.46 speedup to the drawHand() \
> method. This contributes to a 1.40 speedup of paintInterface(). Not bad. 
> Another way of looking at it, paintInterface() used to spend 63% of its time \
> actually painting (m_theme->paint()). Now, paintInterface() spends 98% of its time \
> painting. Hence, painting is now the bottleneck. 
> 
> Thanks,
> 
> Alain
> 
> 

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