[Pixman] [PATCH/RFC] Use OpenMP for bilinear scaled fast paths

[Søren Sandmann]

Søren Sandmann <sandmann at cs.au.dk> writes:

> The main concern from me is making sure that it doesn't cause issues in
> the X server, which is known to do wacky things with signals and
> possibly threads. But the answer to that is to just put it in and get it
> tested.

In some limited testing of this patch, I found that:

- It did indeed cause crashes in the input system with the X server that
  was in Fedora 14. I think these are known bugs that have been fixed in
  newer X servers. (Should we care whether we trigger bugs in older X
  servers?)

- With the X server in Fedora 17 it does not cause crashes.

- When I go to 

    http://ie.microsoft.com/testdrive/Performance/FishIETank/

  the X server will max out 3.5 cores and firefox will use the remaining
  half core, but judging from looking at the fish and the page's FPS
  meter, the performance isn't actually better.

  Profiling shows that 50% to 75% of the time is spent in a function in
  libgomp.so called something like gomp_wait_for_barrier().


Søren