Poor drawing perf in Fennec on android

fennec-poor-drawing-perf.md

• My Bug report

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• Explanation of how opengl drawing in fennec on android works NOPE! looks like the bug for drawing backend on Android is actually this
• Recently slightly helpful thread about poor ESGL perf with cairo on android

Gfx info

the new Azure framework:

• https://blog.mozilla.org/joe/2011/04/26/introducing-the-azure-project/

• http://robert.ocallahan.org/2011/09/graphics-api-design.html

• http://www.basschouten.com/blog1.php/comparing-performance-azure-vs-cairo

• https://wiki.mozilla.org/Gecko:Layers

• https://wiki.mozilla.org/Gecko:Overview#Graphics

• http://benoitgirard.wordpress.com/2012/05/15/off-main-thread-compositing-omtc-and-why-it-matters/

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Profiling

Using the profiling add-on as described here gave native stack trace.

The native stack trace pointed to bits_image_fetch_bilinear_affine_pad_x8r8g8b8 as a likely culprit. Note that the function is actually generated by the MAKE_FETCHERS macro in gfx/cairo/libpixman/src/pixman-bits-image.c

Further research provided this lead: http://www.mail-archive.com/pixman@lists.freedesktop.org/msg00921.html and then this: http://lists.freedesktop.org/archives/pixman/2011-February/001053.html

Yowsers! according to that email, using neon SIMD makes bilinear scaling 6x faster! I our case we are only doing translation btu still...