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List:       kde-panel-devel
Subject:    Re: Review Request: Analog clock painting performance
From:       "Aaron J. Seigo" <aseigo () kde ! org>
Date:       2008-11-30 23:53:22
Message-ID: 200811301653.28463.aseigo () kde ! org
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On Sunday 30 November 2008, you wrote:
> > 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

hm .. indeed .. does the attached patch help with this? if so, this would get 
us this optimization for all uses of Plasma::Svg at the cost of a little extra 
memory overhead.

looking at the callgrind output it looks like that the key is to try and avoid 
hitting KConfigGroup::readEntry.

> >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.

yeah, trying to reduce the painting will be the big win.

-- 
Aaron J. Seigo
humru othro a kohnu se
GPG Fingerprint: 8B8B 2209 0C6F 7C47 B1EA  EE75 D6B7 2EB1 A7F1 DB43

KDE core developer sponsored by Qt Software


["localSvgRectCache.diff" (text/x-patch)]

Index: svg.cpp
===================================================================
--- svg.cpp	(revision 890270)
+++ svg.cpp	(working copy)
@@ -233,19 +233,25 @@
             }
 
             renderer = 0;
+            localRectCache.clear();
         }
 
         QRectF elementRect(const QString &elementId)
         {
-            QRectF rect;
-
             if (themed && path.isEmpty()) {
                 path = Plasma::Theme::defaultTheme()->imagePath(themePath);
             }
 
-            bool found = Theme::defaultTheme()->findInRectsCache(path, cacheId(elementId), rect);
+            QString id = cacheId(elementId);
+            if (localRectCache.contains(id)) {
+                return localRectCache[id];
+            }
 
+            QRectF rect;
+            bool found = Theme::defaultTheme()->findInRectsCache(path, id, rect);
+
             if (found) {
+                localRectCache.insert(elementId, rect);
                 return rect;
             }
 
@@ -332,6 +338,7 @@
 
         Svg *q;
         static QHash<QString, SharedSvgRenderer::Ptr> s_renderers;
+        QHash<QString, QRectF> localRectCache;
         SharedSvgRenderer::Ptr renderer;
         QString themePath;
         QString path;
@@ -484,10 +491,9 @@
 
 void Svg::setImagePath(const QString &svgFilePath)
 {
-    if (d->setImagePath(svgFilePath, this)) {
-    }
-        d->eraseRenderer();
-        emit repaintNeeded();
+    d->setImagePath(svgFilePath, this);
+    d->eraseRenderer();
+    emit repaintNeeded();
 }
 
 QString Svg::imagePath() const

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