[cairo] pixman + OpenMP

[Soeren Sandmann]

Hi,

Parallelizing pixman is interesting already, and will become even more
so in the future, so thanks for experimenting in this area. I may also
be worthwhile thinking about what could be done if changes were also
made at the cairo or X server level.
the cairo or X server level.

> Our result is a little weird.
> It seems that the new form given to the function allows greater
> optimization with GCC 4.3.
> The relative speedup of the new code versus the new code with OpenMP
> enabled seems small.
> Still, we not yet tested this code in a true SMP machine.

Please, when testing pixman performance, run the cairo performance
test suite with "-i <some reasonable number>". The performance tests
you attached all have a very small number of iterations, so the
results are just not very believeable.

The test suite can be restriced to a subset of the tests by running
something like:

       cairo-perf <prefix of the names> -i 5000


Thanks,
Soren