[Webkit-unassigned] [Bug 69515] [Qt] Parallel imagedecoders

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=69515


Zoltan Horvath <zoltan at webkit.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Depends on|                            |71555




--- Comment #5 from Zoltan Horvath <zoltan at webkit.org>  2011-12-01 04:45:45 PST ---
I have a bug for WebCore vs. QtImageDecoder comparison: bug #71555

I made some measurements with libjpeg-turbo, it's related a bit to this topic, so I share my results with you.
About libjpeg-turbo: http://libjpeg-turbo.virtualgl.org/
"libjpeg-turbo is a derivative of libjpeg that uses SIMD instructions (MMX, SSE2, NEON) to accelerate baseline JPEG compression and decompression on x86, x86-64, and ARM systems. On such systems, libjpeg-turbo is generally 2-4x as fast as the unmodified version of libjpeg, all else being equal."

Sounds delicious :) Let's see the numbers:

PC: Intel(R) Core(TM)2 Duo CPUE6550 at 2.33GHz (2 cores)
Slackware 13.1 - 32bit, Qt4.8, r91038,

http://zoltan.sed.hu/WebKit/methanol_imgdecoder/fire.html?iter=1 
libjpeg-turbo (1.1.0): avg 14 339 ms (+/-4.8%) min: 13 195 ms max: 14 897 ms 
libjpeg (v8a): avg 22 423 ms (+/-7.1%) min: 20 926 ms max: 25 140 ms

libjpeg-turbo is 36.1% faster than libjpeg on my imgdecoder-specific benchmark.

Slackware 13.1 - 32bit, Qt4.8, r91038 
http://zoltan.sed.hu/WebKit/methanolx/fire.html?iter=1 
libjpeg-turbo (1.1.0): avg 8 055 ms (+/-15.5%) min: 6 572 ms max: 9 768 ms 
libjpeg (v8a): avg 8 946 ms (+/-11.7%) min: 7 455 ms max: 9 824 ms 

libjpeg-turbo is 10% faster than libjpeg on Methanol benchmark.

It may performs better with more than 2 cores. Impressive gain even on small pictures! What is your opinion guys?

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