[cairo] Pixman ARM Performance

[Jacob Bramley]

Hello all,

I've been having a look at the performance of Pixman on ARM and have 
noticed something strange: It seems that between about 0.12.0 and 
0.15.2, the performance of pixman dropped by about 1.5 times overall. 
Turning on the Neon optimizations in the latest source drastically 
improves a handful of tests, but most are still very slow in comparison 
to 0.12.0 and the overall perforamnce is pretty much the same.

Are you aware of this? Do you know what might be causing it? Am I 
building something incorrectly, perhaps? (I built 0.12.0 too so such a 
mistake would normally result in a slow-down in both versions.)

I can provide the actual benchmark results if they'll be useful. I 
haven't provided them here because there are a lot of numbers!

I'm measuring performance using the "cairo-perf" tool and I'm running on 
a Samsung S5PC100 (Cortex-A8) platform. I've tried building with both 
Code Sourcery's 2007q3 and 2009q1 compilers but the difference this 
makes is insignificant compared to the discrepancy I'm seeing.

Thanks,
Jacob