[cairo] Performance of the refactored Pixman

[Chris Wilson]

On Sun, 2009-07-12 at 13:26 +0300, Siarhei Siamashka wrote:
> The problem with cairo-perf benchmark is that the minimal image size it uses
> is 16x16. For simulating real operations with font glyphs it would make sense
> to also try something like 8x8 or even smaller. Also cairo has its own
> overhead and it takes a bit more to reach the real blitter code.
> 
> So minor regressions in cairo-bench visible as just a few percents may be
> actually tens of percents when dealing with real font glyphs.
> 
> That's why this needs a bit more investigation and maybe some more suitable
> benchmarks.

I completely agree that our benchmarks need continual improvement and
that solely using cairo-perf does incur extra overhead to an ideal
pixman micro-benchmark.

However, if you want to measure glyph performance why not use the glyphs
benchmark in cairo's performance suite? That simply repeats a glyph
string to fill a given image size. Any patches to reduce cairo's
overhead greatly appreciated! ;-)

I also want to stress not to focus too much on micro-benchmarks. If your
benchmarking does not include typical usage, are you sure efforts are
not best spent elsewhere? Which is another reason why I would encourage
you to check cairo-perf-trace.

(I realise that you know this, I'm just trying to point out the small
set of tools already developed. But don't let me discourage you from
writing a full regression suite for pixman! :-)
-ickle