[Webkit-unassigned] [Bug 71555] New: [Qt] Compare WebCore and Qt ImageDecoders

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=71555

           Summary: [Qt] Compare WebCore and Qt ImageDecoders
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Images
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: zoltan at webkit.org
                CC: zbujtas at gmail.com, hausmann at webkit.org,
                    loki at webkit.org, kbalazs at webkit.org, kling at webkit.org


The goal of this bug is to measure the performance and memory consumption differences between WebCore imagedecoders and QImageDecoder, furthermore - based on the results and the discussions - we should decide either to keep the current QImageDecoder implementation or change to WebCore's imagedecoders as we changed for WebCore's one for the N9 browser.

Setup: Slackware 13.1 - 32 bit, Intel(R) Core(TM)2 Duo CPU E6550  @ 2.33GHz, this is a dedicated pc for benchmarking purposes

# Memory consumption (Maximum Resident Set Size (RSS), based on kernels smaps information):

Methanol suite with 18 custom sites for benchmark imagedecoding. 
http://zoltan.sed.hu/WebKit/methanol_imgdecoder/fire.html?iter=1

 WebCoreImageDecoders: avg 295 624 kbytes +/- 1.6% (min: 290 804 kbytes, max: 303 334 kbytes)
 QtImageDecoders: avg 293 556 kbytes +/- 2.1% (min: 286 052 kbytes, max: 303 804 kbytes)

Methanol suite with the first individual 23 sites from alexa top100. (mirrored) 
http://zoltan.sed.hu/WebKit/methanolx/fire.html?iter=1

 WebCoreImageDecoders: avg 70 856 kbytes +/- 2.5% (min: 68 772 kbytes, max: 73 736 kbytes)
 QtImageDecoders: avg 70 639 kbytes +/- 1.1% (min: 70 056 kbytes, max: 72 016 kbytes)

As we see there are no big differences in the numbers, the memory consumption is almost the same with both type of implementation.

# Performance (Methanol provided the results)

http://zoltan.sed.hu/WebKit/methanol_imgdecoder/fire.html?iter=1
 QtImageDecoders: avg 15 632 ms +/- 5.1% (min: 14 344ms, max: 16 406ms)
 WebCoreImageDecoders: avg 20 895 ms +/- 5.6% (min: 19 116ms, max: 22314ms)

WebCoreImageDecoder is 33.6% slower.

Methanol suite with the first individual 23 sites from alexa top100. (mirrored) 
http://zoltan.sed.hu/WebKit/methanolx/fire.html?iter=1
 QtImageDecoders: avg 7 492ms +/- 6.5% (min: 7 124ms, max: 8 216ms)
 WebCoreImageDecoders: avg 7 798ms +/- 9.06% (min: 7 332ms, max: 9 153ms)

WebCoreImageDecoder is 4.08% slower.

Based on this results I think we will keep QImageDecoders, but I'm interested in your thoughts!

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