PDA

View Full Version : Houdini 12 OpenCL - SLI?


hiasakite
02-24-2012, 06:24 PM
Has anyone found any information as to whether H12 will support multiple graphics cards for its OpenCL calculations? Or will you, even in an SLI setup, have to select one of your cards that is going to be used, while the other one sits idle?

I'm just in the process of planning out a new workstation and can't wait for H12 to come out for its accelerated pyro fx etc. Top choice right now is a GTX 580 3GB, though the budget would allow for a second one in SLI _if_ that would actually double the number of shaders used for calculations.

Cheers

SoLiTuDe
02-24-2012, 08:41 PM
http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=22991

"SLI or crossfire cards are treated as separate OpenCL devices, so each device will only see 1.5GB. The GTX590 is really just two GPUs on one card with a SLI bridge built-in. I don't think GPU acceleration for H12 will use multiple OpenCL devices, but this could change by release."

Afaik this is still the case. Each card is it's own opencl device.

hiasakite
02-24-2012, 09:18 PM
I'd seen that thread but as I understand it the question there was whether the video ram would add up (so, 6gb with two 3gb cards), which it doesn't. I don't think they answered whether more than one OpenCL device would/could be used for the calculation (each using its own memory).

SoLiTuDe
02-25-2012, 06:24 AM
I'd seen that thread but as I understand it the question there was whether the video ram would add up (so, 6gb with two 3gb cards), which it doesn't. I don't think they answered whether more than one OpenCL device would/could be used for the calculation (each using its own memory).


" I don't think GPU acceleration for H12 will use multiple OpenCL devices " I think that pretty much sums it up.

olson
02-27-2012, 03:59 PM
From my understanding of it only one device will be used for one simulation. However if you have more than one device you can open multiple instances of Houdini and specify different devices for each simulation. The multiple devices just won't be able to all work on the same simulation.

This is not an inherent limitation of OpenCL. Multiple devices can be used for a single task but this requires the software to balance and distribute the workload amongst the devices. So in theory the situation could change in future releases as the new features that take advantage of OpenCL mature and evolve.

CGTalk Moderation
02-27-2012, 03:59 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.