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Why does enabling OpenCL cause my SIM to fail?


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Hi

Curious why enabling 'OpenCL' in the Advanced TAB of my pyrosolver causes my sim to fail.

What happens is theat when enabled, I can simulate about the first 30-40 frames of a smoke sim only.

Is there some other OpenCL related setting in application preferences?

AFAIK, OpenCL should be fully supported on my setup, Ubuntu Linux 16.04 and NVIDIA Titan X Pascal GPU. Possibly Nvidia driver related?

Edited by art3mis
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It probably fails because it runs out of vRam memory.

On Windows I have not found any evidence that OpenCL actually works with my nVidia based card. When I turn it on I  see no GPU usage at all. Which is a shame because I have 1,920 cores doing nothing.

Edited by Atom
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3 hours ago, Atom said:

It probably fails because it runs out of vRam memory.

On Windows I have not found any evidence that OpenCL actually works with my nVidia based card. When I turn it on I  see no GPU usage at all. Which is a shame because I have 1,920 cores doing nothing.

You should get that checked out. I get 4x times speed ups with smoke simulations in Linux on a Gtx980 vs Xeons. I personally don't think you know how to setup OpenCL and think just turning on the checkbox does the trick. 

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6 hours ago, Atom said:

On Windows I have not found any evidence that OpenCL actually works with my nVidia based card. When I turn it on I  see no GPU usage at all. Which is a shame because I have 1,920 cores doing nothing.

I'm not sure how you monitor your GPU usage..but I use GPU-Z>Sensors and watch my GPU Core Clock...
Normally, it sits at 200MHz...this is because (most likely) your Nvidia 3D Performance setting is set at Optimal (ie. Minimum)...I set mine to Adaptive (wouldn't bother setting one by one for each 3D app, just do 'globally')...so any 3D s/w that uses OpenCL...when it kicks in, I'd see my GPU Core Clock shoot up to 1500MHz..(or more for beefier cards)

(Win 7, GTX 1070, Driver 382.05)

Edited by Noobini
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"I personally don't think you know how to setup OpenCL and think just turning on the checkbox does the trick. "

Hi marty.

You're probably right. Can you point me in the right direction? What else needs to be done to enable OpenCL on my sims?

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20 minutes ago, art3mis said:

"I personally don't think you know how to setup OpenCL and think just turning on the checkbox does the trick. "

Hi marty.

You're probably right. Can you point me in the right direction? What else needs to be done to enable OpenCL on my sims?

Well -what are you trying to use OpenCL for?

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hmmm. so as a programmer you should know that code is only applicable to the areas that are coded right? So you need to be more specific.

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I'm in the same boat, I thought just turning on the check box, inside the pyro or flip solver, is supposed to cause the simulator to make full use of my GPU.:huh:

I think that is generally the end user expectation.

Edited by Atom
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so you've verified in your Nvidia Control Panel that 3D Performance is not set at Snail's Pace right ?

Optimal = always at crap speed
Maximum = always at full speed (even if nothing needs it) = plain silly
Adaptive = best

http://nvidia.custhelp.com/app/answers/detail/a_id/3130/~/setting-power-management-mode-from-adaptive-to-maximum-performance

Edited by Noobini
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This old, but still relevant, post explains GPU acceleration very well, and has tips on how to optimize your sim for openCL. There is also an attached file that clearly shows the kind of speedup you can expect:

https://www.sidefx.com/forum/topic/25234/

With that test scene, i'm easily getting 4x to 5x speed up with Quadro M4000.

 

Edited by KarlRichter
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6 hours ago, Atom said:

Do you have a link to an example file that demonstrates this 4x speed up?

Nothing to share as it's a production file -but honestly when you hear this whinging and then one builds a smoke sim in <20mins that goes 20fps on the GPU and 5 fps on CPU, you have to wonder if people are actually trying at all...

So did you read the Flip OpenCL section? It says Viscosity & Pressure ONLY are solved in OpenCL, which means a whole of the the sim isn't. Users are expected to read documentation but hey, kids these days don't like doing that I guess.

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7 hours ago, haggi said:

I suppse the end user will expect some speedup in pyro or smoke sims if he reads this:

And there are only a few restrictions mentioned in the docs.

I got 2x on the pyro and 4x on the smoke solver, adding turbulence nodes to the smoke covered the gap.  This is on Linux, not MacOs where it's not the case.

The overriding issue here is that people read 'OpenCL' and think wham! free speed ups! Sounds like when gamers take the 'must fill up the ram so it can be faster' into the real world -haha

 

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