[webkit-qt] [Qt] Strong performance degradation with DirectFB since r122720

Brianceau, Julien JBrianceau at nds.com
Fri Sep 14 02:55:20 PDT 2012

Hi Zoltan,

Thank you for your answer.

Here are the results with Qt5 on another board (a less powerful one : STi7105 with sh4 arch) :

-          using Qt 5 with QPA DirectFB platform

-          using qtwebkit based on r126284 :

            commit c311cf639cc1d6570d67b0a80a8ba04dc992a658
            Author: Simon Hausmann simon.hausmann at nokia.com<mailto:simon.hausmann at nokia.com>
            Date:   Wed Aug 22 13:36:28 2012 +0200
            Imported WebKit commit 35255d8c2fd37ba4359e75fe0ebe6aec87687f9c (http://svn.webkit.org/repository/webkit/trunk@126284)

-          using the same qtwebkit with changeset 122720 reverted

With r126284 based webkit version, I get 11,3 displayed fps, with a CPU usage of more than 95%
With r126284 based webkit version with changeset 122720 reverted, I get 25,6 displayed fps, with a CPU usage of about 90%

Regarding http://lists.webkit.org/pipermail/webkit-qt/2012-February/002470.html, I think we can keep QPixmap as native image type, and use webkit image decoders as well.



De : Zoltan Horvath [mailto:zoltan at webkit.org]
Envoyé : jeudi 13 septembre 2012 19:44
À : webkit-qt at lists.webkit.org; Brianceau, Julien
Objet : Re: [webkit-qt] [Qt] Strong performance degradation with DirectFB since r122720

Hi Julien,

There are several reasons, please check the mail archive and the related bug entries.

Thread about the discussion: http://lists.webkit.org/pipermail/webkit-qt/2012-February/002470.html

Can you verify this results with Qt5 as well?


On Thu, 13 Sep 2012 19:31:57 +0200, Brianceau, Julien <JBrianceau at nds.com> wrote:

Hello all,

I wonder why this changeset has been made : http://trac.webkit.org/changeset/122720

QPixmap and QImage are not the same with QPA platforms plugins (e.g. DirectFB).

To give you an idea of the performance issue, I performed the following test on my ST armv7 board :

-          using a Qt 4.8 using QPA with DirectFB platform

-          using WebKit r122719 and r122720

-          using this URL : http://www.craftymind.com/factory/guimark3/bitmap/GM3_JS_Bitmap.html in a QWebView sized to 1280x720 (with webkit 1 build)

With r122719, I get 50,7 displayed fps with a CPU usage of about 25%
With r122720, I fall to 25,3 displayed fps with a CPU usage of more than 90%

Is it possible to revert this commit, or at last provide a compilation option to keep QPixmap as native images ?

Please ask if you need further information,



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