[Gegl-developer] GPU support

[Richard H.]

Hello,

>Implementing multi-threading in GEGL is out of my scope and I'm not
>even sure if it's in GEGL's scope.

I understand that as your project's task is adding OpenGL support. In my
opinion, multi-CPU support would be more important, but that is of course
another big task/project.

> GEGL is pretty low-level and
>threading can be implemented on top of GEGL by the relevant client
>(i.e. GIMP).

I don't understand this. How should GIMP provide threading support for GEGL
processors? I mean, if you for instance scale a picture using GEGL, it is one
GEGL operation. How can GIMP create multiple threads for this?

> Furthermore, be aware that threading doesn't really map
>into multiple cores and not using threads doesn't really mean that the
>code will not be parallelized[1].

I had a look at Graphite/autopar and can say: Wow! Splitting loops to
multiple threads automatically
[http://gcc.gnu.org/ml/gcc/2009-03/msg00239.html] is a good thing, but I think
it's not true that threads don't map into multiple cores automatically. That's
what threads (or processes, when threads are processes with same address
space) are for.

>I'm not really an expert with regards to how GEGL uses threading
>frameworks (if at all) to parallelize tile/rectangle-level operations.

I think it doesn't use threads at all and is designed for single-threaded use
only... :/

> My work will be concerned with accelerating pixel-level operations by
>parallelizing each pixel operation in the GPU.  The key in my work is
>that all pixel operations should (theoretically) work in parallel.

That would indeed be very nice to have.

-- 
Richard H. (via www.gimpusers.com)