Am 04.01.2016 um 22:55 schrieb Theogott:

> Some years ago we had a POV-Ray version using SSE. WHY?
> For a few (100% ?) more speed in some scenes.

Actually that's SSE2, and we still have it.

> 100% more speed is completely uninteresting when we talk about OpenCL and GPU's.
> We start here with 1000% faster and we go to 30 times faster if you have a "two
> GPU graphics card". For actually 350 EUR from Ebay (like my HD 7990).

You need to put that into perspective, however, with the development
effort that goes with it.

Making use of the SSE2 instruction set extensions for x86 CPUs is just a
matter of flipping a switch in the compiler settings. Making use of GPUs
might require a rewrite of major portions of the code.

Just look at how long it took to get the multi-core support released.


I'm not saying GPU support is a bad idea. I'm not saying POV-Ray will
never go down that road. All I'm saying is that (1) it'll be an
assload(*) of work to get there, and (2) please give us a break now and
cease your attempts to campaign for it.

Your message has been received, there's little to nothing left you or
anyone could add to the discussion that would speed things up, and the
whole topic is pretty frustrating for the developers (at least for me),
because all we can do about it -- time and again, whenever the issue
pops up -- is say, yup, that would really be neat to have, but don't
expect any visible progress in that direction any time soon, because...
and then give you a list of whatever obstacles we currently consider the
most adverse to get there.

Some obstacles have been addressed in recent times by the GPU
manufacturers. Others are more fundamental; and while potential
solutions have been found thanks to an improved understanding of those
issues, and I reckon that there are no real show stoppers along the road
anymore, these fundamental obstacles do leave us with that
aforementioned assload of work required to get around them.


I might also add that the very first step of that assload of work will
be cleanup and modularization of the existing code, which is something
that's already being done as we speak, for plenty of other reasons.


(* That's "ass" as in "donkey", mind you ;))

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