Parallel processing already has proven itself in V3.7, so getting 512 cores to
work parallel should get us impressive results I guess.

It probably would not be possible to let every core process a pixel, but maybe
some pipelining would work were one core processes certain aspects and passes
the result onto a queue that the next core picks up and processes farther, all
running mini algorithms that fit in their own private cache.

see http://www.nvidia.co.uk/page/tesla_computing_solutions.html or
http://www.nvidia.co.uk/object/fermi_architecture_uk.html

Cheers,
Louis

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Louis <nomail@nomail> wrote:
> It probably would not be possible to let every core process a pixel

  How do you suggest for the GPU to process the scene data (which it needs
to trace rays in the first place), which might take hundreds of megabytes of
memory?

  And does CUDA already support conditional recursion?

-- 
                                                          - Warp

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Louis wrote:
> Parallel processing already has proven itself in V3.7, so getting 512
> cores to work parallel should get us impressive results I guess.
> 
> It probably would not be possible to let every core process a pixel, but
> maybe some pipelining would work were one core processes certain aspects
> and passes the result onto a queue that the next core picks up and
> processes farther, all running mini algorithms that fit in their own
> private cache.

Did GPUs change fundamentally since the last time (or last 200 times) other 
people suggested "add GPU support to POV-Ray"?

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Louis schrieb:
> Parallel processing already has proven itself in V3.7, so getting 512 cores to
> work parallel should get us impressive results I guess.

Say, just to make sure - you didn't happen to read Darren New's recent 
posting in povray.off-topic and took it serious, did you?

Just search the POV-Ray newsgroups (both this one and others) for "GPU" 
or "CUDA" for the problems involved, and the current position of the POV 
developers' team (and others) on this matter... or, well, at least the 
position from two or three months ago.

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clipka <ano### [at] anonymousorg> wrote:
> Louis schrieb:
> > Parallel processing already has proven itself in V3.7, so getting 512 cores to
> > work parallel should get us impressive results I guess.
>
> Say, just to make sure - you didn't happen to read Darren New's recent
> posting in povray.off-topic and took it serious, did you?
>
> Just search the POV-Ray newsgroups (both this one and others) for "GPU"
> or "CUDA" for the problems involved, and the current position of the POV
> developers' team (and others) on this matter... or, well, at least the
> position from two or three months ago.

Ok, so I wasn't the first to think of it :-s

After thinking about it, I guess such one should only start supporting such
architectures when a platform has been established that runs on at least two
competitor's hardware.

For my use, these cards are a little too expensive any way.

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Louis schrieb:

> Ok, so I wasn't the first to think of it :-s

Indeed :-)

> After thinking about it, I guess such one should only start supporting such
> architectures when a platform has been established that runs on at least two
> competitor's hardware.

... and when the architecture becomes flexible enough for the tasks at 
hand. The requirements of a raytracer differ a lot from those of a 
rasterizer.

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clipka <ano### [at] anonymousorg> wrote:
> Louis schrieb:
>
> > Ok, so I wasn't the first to think of it :-s
>
> Indeed :-)
>
> > After thinking about it, I guess such one should only start supporting such
> > architectures when a platform has been established that runs on at least two
> > competitor's hardware.
>
> ... and when the architecture becomes flexible enough for the tasks at
> hand. The requirements of a raytracer differ a lot from those of a
> rasterizer.

Is it not the case that the big two (three?) (NVidia and ATI and (?)) are
developing a C-like language (common) which might deal with this?  I.E. using
the GPU's of NVidia will directly translate to t'other.

Anyway, it would be great if we could use the power of the big GPU's to do a lot
of our maths while our CPU's sit there and deal with the need for AntiVirus
software, overbearing operating systems, instant messaging, and all of that
whilst streaming TV over our 't'internet connection, AND rendering 920,332,986
spheres in POVRAY!


Sorry to mention my 920,332,986 spheres again (fourth time today) but I'm quite
impressed by POVRAY's ability!  It did it in the time it takes to watch an
epsiode of "Scrubs" on MegaVideo but without affecting the playback!  Bonza!

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"arblick spule" <aspule> wrote:
> Anyway, it would be great if we could use the power of the big GPU's to do
> a lot of our maths while our CPU's sit there and deal with the need for
> AntiVirus software, overbearing operating systems, instant messaging, and
> all of that whilst streaming TV over our 't'internet connection, AND
> rendering 920,332,986 spheres in POVRAY!

What will you say if antivirus software and instant messengers also move to 
the GPU "because the CPU is busy with all that other useless software"? ;)

Post a reply to this message

arblick spule wrote:
> Is it not the case that the big two (three?) (NVidia and ATI and (?)) are
> developing a C-like language (common) which might deal with this?  I.E. using
> the GPU's of NVidia will directly translate to t'other.

Not the case, at the moment. They may be working towards using the same
language, but I stopped following along. Right now, it isn't there yet.

> Anyway, it would be great if we could use the power of the big GPU's to do a lot
> of our maths while our CPU's sit there and deal with the need for AntiVirus
> software, overbearing operating systems, instant messaging, and all of that
> whilst streaming TV over our 't'internet connection, AND rendering 920,332,986
> spheres in POVRAY!

It would be great, yes. The problem that what POV-Ray requires of a
processor is not what graphics cards provide. When either graphics cards
get complex enough to handle the requirements of a general raytracer, or
someone comes up with an algorithm that works, or someone invests the
time placing all the branching code on the CPU with the matrix math on
the GPU and finds that it does indeed work faster, that is when we may
see POV-Ray start that direction. Not before then, and definitely not
before 4.0.

> Sorry to mention my 920,332,986 spheres again (fourth time today) but I'm quite
> impressed by POVRAY's ability!  It did it in the time it takes to watch an
> epsiode of "Scrubs" on MegaVideo but without affecting the playback!  Bonza!

It is amazing, isn't it?

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Warp <war### [at] tagpovrayorg> wrote:
> Louis <nomail@nomail> wrote:
> > It probably would not be possible to let every core process a pixel
>
>   How do you suggest for the GPU to process the scene data (which it needs
> to trace rays in the first place), which might take hundreds of megabytes of
> memory?
>
>   And does CUDA already support conditional recursion?
>
> --
>                                                           - Warp

#1: GPU has a bank of global memory which is fully accessable to every core.
Sizes in new cards vary, though the very bottom of the range is probably 128MB
(top of the range is 4GB, general consumer stuff is 256-768MB). Newer GPUs also
have the ability to directly access host RAM.

#2: No, but next gen (Q1 2010) will. IIRC this was annouced in October. Speed
would depend on quite how branchy it is.


People are doing raytracing on CUDA already (are I think they're quite speedy -
look up NVIDIA's Optix), though I imagine they can't quite match the feature set
of pov-ray... and it's probably these features that don't map to GPUs. I must
admit to being fairly ignorant when it comes to interals of ray-tracers.

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