## ATI released OpenCL SDK with hardware support

Discussions related to GPU Acceleration in LuxRender

### Re: ATI released OpenCL SDK with hardware support

With the code change and resolution reduction I have managed to get some figures out. It should be noted though that my GPU is absolutely no match for yours
(according to wikipedia)
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Model   GFLOPS8400GS   ~43HD4870   1200

Results are disappointing with optimal localThreads = 128
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doug@l64dev:~/dev/mandelgpu/MandelGPU$./mandelGPU 0 1 10000Usage: ./mandelGPU <use CPU device (0 or 1)> <use GPU device (0 or 1)> <max. iterations>OpenCL Device 0: Type = TYPE_GPUOpenCL Device 0: Name = GeForce 8400 GSOpenCL Device 0: Compute units = 1Reading file 'rendering_kernel.c' (size 2086 bytes)Rendering time: 0.620000 secs (Sample/sec 123871 Max. Iterations 10000)Rendering time: 0.380000 secs (Sample/sec 202105 Max. Iterations 10000)doug@l64dev:~/dev/mandelgpu/MandelGPU$ ./mandelCPU 10000Usage: ./mandelCPU <max. iterations>Rendering time: 0.730000 secs (Sample/sec 105205 Max. Iterations 10000)Rendering time: 0.730000 secs (Sample/sec 105205 Max. Iterations 10000)

back up at 1024x768, the margin increases. GPU is about 140% power of single Q8300 core
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doug@l64dev:~/dev/mandelgpu/MandelGPU$./mandelGPU 0 1 10000Usage: ./mandelGPU <use CPU device (0 or 1)> <use GPU device (0 or 1)> <max. iterations>OpenCL Device 0: Type = TYPE_GPUOpenCL Device 0: Name = GeForce 8400 GSOpenCL Device 0: Compute units = 1Reading file 'rendering_kernel.c' (size 2086 bytes)Rendering time: 4.950000 secs (Sample/sec 158875 Max. Iterations 10000)Rendering time: 5.060000 secs (Sample/sec 155421 Max. Iterations 10000)Done.doug@l64dev:~/dev/mandelgpu/MandelGPU$ ./mandelCPU 10000Usage: ./mandelCPU <max. iterations>Rendering time: 7.380000 secs (Sample/sec 106563 Max. Iterations 10000)Rendering time: 7.390000 secs (Sample/sec 106418 Max. Iterations 10000)Done.

dougal2

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### Re: ATI released OpenCL SDK with hardware support

Hi

I took the source code and compiled it on my Mac running OS X 10.6.2 - I had to change the make files and how the headers are included to get it to compile. Playing with Makefiles has never been my strong point, but i managed it anyway.

Works a charm! Very nice little bench mark.

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OpenCL Device 0: Type = TYPE_GPUOpenCL Device 0: Name = GeForce 9400MOpenCL Device 0: Compute units = 2Reading file 'rendering_kernel.c' (size 2086 bytes)Rendering time: 0.585615 secs (Sample/sec 819651 Max. Iterations 10000)Rendering time: 1.997915 secs (Sample/sec 240250 Max. Iterations 10000)

random question, the render goes very pixilated when you zoom in really far... any way of improving this? I guess its limited because of rendering time right?

Eros

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### Re: ATI released OpenCL SDK with hardware support

Eros wrote:random question, the render goes very pixilated when you zoom in really far... any way of improving this? I guess its limited because of rendering time right?

If you're zooming very far, it might be numerical aliasing due to the float type limited precision.

Jeanphi
jeanphi

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### Re: ATI released OpenCL SDK with hardware support

jeanphi wrote:
Eros wrote:random question, the render goes very pixilated when you zoom in really far... any way of improving this? I guess its limited because of rendering time right?

If you're zooming very far, it might be numerical aliasing due to the float type limited precision.

Yup, it is so easy and so fast to zoom in that you end the 32bit floating point resolution very soon. The only solution would be to use 64bit floating points instead of 32bit but there are very few boards supporting them at the moment (I think the new ATI HD5xxx series has the hardware support for double).

The other option would be the use software implemented floating point numbers with user defined resolution ... this stuff is so fast that it could handle it quite well even in software.

xDoug, your card has 8 stream processor, the performances aren't that bad if you think mine has 800 and the new ATI HD5870 1600 (!) Overall it is nice to see the promised cross-platform compatibility of OpenCL to be real, not only on paper. This is one of the very basic requirement for Luxrender.

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### Re: ATI released OpenCL SDK with hardware support

wow, up to the floating point precision that quickly, thats quite amazing.

My coding experience is limited to data analysis using a god awful framework which is ok when you are compiling against it but it also comes with a C interpreter which allows you to get away with some horrible stuff... and happily segfaults at random. Just out of habit i guess i always use doubles when floats would be just fine. I did notice a distinct lack of them and was thinking... mmm change them to doubles... though that would probably have been the stupidest idea ever.

Still very cool work there! Its probably the second display of how OpenCL can speed up calculations using the GPU iv looked at on the mac, even on this poor little macbook pro. I will likely point a few people at it as a demo.

Eros

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### Re: ATI released OpenCL SDK with hardware support

jeanphi wrote:I'll sure try it as soon as I manage to run the CLinfo application without a segfault when it initializes

BTW, aren't you using Ubuntu 9.10 ? The ATI beta driver is for 9.04, may be the problem is there

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### Re: ATI released OpenCL SDK with hardware support

Hi,

According to AMD developer forum it seems the issue is the X server bundled with Ubuntu 9.10 (too recent and not officially supported by AMD).

Jeanphi
jeanphi

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### Re: ATI released OpenCL SDK with hardware support

I've hit that problem as well. I did see one post where someone claimed it would work with the 9.11 driver but as expected it didn't. It's a shame, I'd quite like to have a try of this!

I spent quite a while trying to get it working last night, I've changed my fglrx driver many many times now
Down Rodeo

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### Re: ATI released OpenCL SDK with hardware support

I finished the port of SmallPT (even if there is about nothing left from the original SmallPT).

Short version: I'm here, in front of this monster running at 25,000,000 of samples per second

Long version: It always starts in the same way, with the OpenCL version running at about the same speed of one core. Than you start to hammer here and there and it runs a load faster. It feels more like voodoo magic than programming but who care, it works nearly in real time. Sources and some number are available here: http://davibu.interfree.it/opencl/small ... ptGPU.html

The usual naif video is available here: http://vimeo.com/8013005 (or http://www.youtube.com/watch?v=TAZsC3buDug)

I go back playing with my little world made only of spheres, it is too funny
Last edited by Dade on Sun Dec 06, 2009 5:31 pm, edited 1 time in total.

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### Re: ATI released OpenCL SDK with hardware support

OMG

That is nothing short of amazing

dougal2

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