[Bf-committers] Cycles split kernel improvements

[Sergey Sharybin]

Hi,

Was doing some code review today and found that people are not aware of
what was done from user's perspective in cycles_split_kernel branch.

(Very)Simplified summary:

- Lots of bug fixes and re-implementation of code which was fully wrong,
making us wondering -- how things were managing to work before. This
includes fixes for shading artifacts, system stalls, crashes.

- Some speedup work was already done. Mainly related on better
implementation of work stealing.  In our tests it is almost up to 2x
speedup comparing to early-january,

What happens now:

- Mai is working hard on getting last bits of issues to be solved, so we
can merge her work into master.

- We are looking into implementing the shadow rays optimizations which
gives about 2x on scenes like koro.blend but currently introduces some
slowdown to other files like BMW.

- Hristo is working on SSS/Volume support on top of split kernel branch.
Those are also planned for inclusion to master soon.

We've got a separated spread-sheet to keep track on performance of split
kernel branch there:
https://docs.google.com/spreadsheets/d/1YC0R06lLDn0pECDDridUTxEZDboAzzyjotZLQmOi3Og/edit#gid=0

That's it for now.

-- 
With best regards, Sergey Sharybin