[Intel-gfx] Howto enable i830FALLBACK, regressions with xorg/intel from git.

[Clemens Eisserer]

Hi again,

Sorry for the last email and for all the useless traffic, I was so
enthusiastic to find the regression that I oversaw a bug in my code -
I created a picture without explicitly setting repeat in
pictureformat, but was passing CpRepeat to CreatePicture, so it was
uninitialised and I guess this was causing a fallback. If I change
that I get almost the same results as with 2.1.1 (maybe 10% lower).

However in some real-work workloads I still see regressions down to
50% of the original speed, without noticing fallbacks with oprofile or
a few methods eating all the CPU cycles. I also don't get fallback
messages with debug turned on.
The really strange thing is Xorg consumes often only 30-60% of the
cpu, but my client is waiting for it.

Hopefully I will be able to find a small test-case which triggers the probem.

Thanks, Clemens