[Bf-cycles] Nvidia Titan Cycles Performance?

[Brecht Van Lommel]

Hi Jordan,

On Fri, Apr 12, 2013 at 7:01 PM, Jordan Miller <jrdnmlr at gmail.com> wrote:
> So I'm interested in using Blender Cycles to do complex visualizations of advanced manufacturing and fluid mechanics.
>
> Is the Nvidia Titan and even two or three titans wired via SLI a useful option?
> http://www.nvidia.com/titan-graphics-card
>
> Teh internets don't agree on Titan performance with Cycles, so I figured I go straight to the source to ask.

I haven't tested it so I don't know anything more. On blenderartists
someone mentioned Octane on Titan was 50% faster than GTX 580 and 10%
slower than GTX 690 (which is a dual GPU). Reading the specifications
that seems about what you might expect, corresponding roughly to clock
speed x number of cores.

Multiple cards can be used, but note that for Cycles you should
disable SLI. SLI is a system to run OpenGL/DirectX games across
multiple cards but for Cycles it causes more memory usage.

> I know the issues may be what is currently supported vs. what is planned in the future. I imagined Blender Foundation may opt for a titan workstation for each developer for the next open movie project?

Too soon to tell, and every few months there's a new graphics card or
price change.

> Is the main advantage of the titan NOT performance but instead the vRAM size to allow very large and complex scenes (e.g. paving the way for hair rendering in cycles?)?

The extra memory is indeed welcome for GPU ray tracing. Very large and
complex scenes is relative of course, e.g. 4GB to 6GB means you can
store some more polygons or increase image resolutions, but it's not
that big a difference.

Also the reason hair rendering does not currently work on the GPU is
not because of memory usage. We rendered Big Bug Bunny with about 4GB
of memory I think, so in principle it should be possible to fit quite
a bit of hair in that kind of memory for Cycles too once we get it
working.

> I'm also interested in your thoughts in terms of cost effectiveness. Luckily cost itself is less of a concern to us for this machine as much as raw Cycles performance and ability to do complex fluid visualizations/simulations with Cycles rendering for photorealism.

I guess if you're going to spend something in that price range it's a
tradeoff between the GTX 690 which has less memory but probably is a
bit faster, versus the Titan which has more memory but is a bit
slower. But I'm not sure because I haven't done any benchmarks.

> And can the Blender compositor use GPU? :-D

The compositor supports GPU acceleration for a few blur nodes but no
other nodes, so it doesn't help that much overall.

Brecht.