[Pixman] performance of bilinear_interpolation

[Siarhei Siamashka]

On Fri, 27 Sep 2013 16:42:08 +0100
Chris Wilson <chris at chris-wilson.co.uk> wrote:

> On Fri, Sep 27, 2013 at 01:17:45AM +0300, Siarhei Siamashka wrote:
> > Unfortunately, all that I could record so far is a broken trace :-(
> > Maybe somebody else will be more lucky? If anybody is interested, just
> > go to http://manichord.com/opensign/ffdebug/ffscroll.html in Firefox,
> > press ctrl-+ to zoom the page a bit and scroll it left/right for a
> > while. The Firefox browser needs to be launched by the cairo-trace tool.
> 
> Lots of bugs in cairo-trace exposed by trying to record recent ff. :(
> All appear to be fixed, and I've upload a firefox-canvas-scroll.trace to
> the cairo-traces.git

Thanks for the fix. Firefox traces can be recorded now. I had a
look at the firefox-canvas-scroll trace, but it does not fully
represent this interesting use case. The trace has too much of
blt (which eclipses the other operations), and too little of
bits_image_fetch_bilinear_affine_pad_x8r8g8b8.

Profiling this trace shows:

33.18%  cairo-perf-trac  libpixman-1.so.0.31.1 [.] sse2_blt.part.10
29.17%  cairo-perf-trac  libpixman-1.so.0.31.1 [.] sse2_composite_over_8888_8888
15.86%  cairo-perf-trac  libpixman-1.so.0.31.1 [.] sse2_fill
 8.63%  cairo-perf-trac  libpixman-1.so.0.31.1 [.] bits_image_fetch_bilinear_affine_pad_x8r8g8b8
 3.76%  cairo-perf-trac  liblzo2.so.2.0.0      [.] lzo2a_decompress
 1.06%  cairo-perf-trac  libc-2.15.so          [.] __memcpy_ssse3

While running "perf record -p `pidof firefox" and profiling only the
scrolling part in Firefox (without any possible initial setup overhead)
seems to show no major blt usage:

25.67%  firefox  libpixman-1.so.0.31.1 [.] sse2_composite_over_8888_8888
24.86%  firefox  libpixman-1.so.0.31.1 [.] bits_image_fetch_bilinear_affine_pad_x8r8g8b8
14.84%  firefox  libpixman-1.so.0.31.1 [.] sse2_fill
 1.87%  firefox  libpixman-1.so.0.31.1 [.] sse2_blt.part.10
 0.82%  firefox  libc-2.15.so          [.] __memcpy_ssse3


I tried to record a new Firefox trace myself and also make it
shorter, so that it is usable on much slower embedded systems:

https://github.com/ssvb/trimmed-cairo-traces/raw/86014d9a02d1/benchmark/t-firefox-canvas-swscroll.lzma

35.55%  cairo-perf-trac  libpixman-1.so.0.31.1 [.] bits_image_fetch_bilinear_affine_pad_x8r8g8b8
18.83%  cairo-perf-trac  libpixman-1.so.0.31.1 [.] sse2_composite_over_8888_8888
 7.71%  cairo-perf-trac  libc-2.15.so          [.] __memset_sse2
 7.23%  cairo-perf-trac  liblzo2.so.2.0.0      [.] lzo2a_decompress
 5.01%  cairo-perf-trac  libpixman-1.so.0.31.1 [.] sse2_fill
 2.71%  cairo-perf-trac  libc-2.15.so          [.] __memcpy_ssse3
 2.48%  cairo-perf-trac  libpixman-1.so.0.31.1 [.] sse2_blt.part.10

Additionally, Firefox is configured to use client side software
rendering by setting gfx.xrender.enabled=false in about:config
(in order to make it behave more like it behaves in Android).

-- 
Best regards,
Siarhei Siamashka