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OpenCL

sharlybg
Adept II

Re: Blender Cycles(Opencl on AMD GPUS)

Hi I'm a blender user too (but native french peaker).I use blender For Archiviz at professionnal level.But when it's come to speak about productivity there's big shame.My Boss now want to pay cash for high end workstation.I'm the one that can advise the boss about which component are enought powerfull or stable to help us get more Fast rendering.

Me like many many blender user wish that AMD radeon card will be full support by cycles.but it's not the case and cycles developper said that:

"OpenCL support for AMD

is currently on hold. Only a small subset of the entire rendering kernel can currently be compiled, which leaves this mostly at prototype. We will need major driver or hardware improvements to get full cycles support on AMD hardware. For NVidia CUDA still works faster, and Intel integrated GPU's are unlikely to give any speed improvement over CPU rendering.

In Blender 2.65, OpenCL is not available as a choice in the UI by default. The environment variable CYCLES_OPENCL_TEST can be defined to show it, which can be useful for developers that want to test it. The OpenCL kernel is located in 2.65/scripts/addons/cycles/kernel. In the file kernel_types.h specific functionality can be enabled/disabled for testing, without recompiling Blender."

sentence below explain why luxrender work on AMD and why it doesn't for Cycles:

"

The path tracing kernel is currently a single big kernel, much bigger than typical OpenCL code. There are about 40 shading nodes, 10 BSDF's, etc.

Splitting it up into smaller parts may help, but even then compiling only the shading nodes execution code fails. This would be quite difficult to split up. An alternative would be to compile a kernel for each material in the scene, but I don't have much faith in complex node setups compiling reliably then, and scene startup time would increase considerably.

If at all possible I would like to avoid splitting up the kernel in many pieces, mainly because it makes extending the code much harder (we're only getting started in terms of number of features). And also because I haven't really seen this demonstrated working efficiently in other renderers yet, e.g. NVidia Optix also uses a single kernel."

AMD

The immediate issue that you run into when trying OpenCL, is that compilation will take a long time, or the compiler will crash running out of memory. We can successfully compile a subset of the rendering kernel (thanks to the work of developers at AMD improving the driver), but not enough to consider this usable in practice beyond a demo.


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mberger
Adept I

Re: Blender Cycles(Opencl on AMD GPUS)

I think register spilling is broken at the AMDIL level.  cycles depends on register spilling for nvidia it uses 24 max-register setting. to force compiler to spill.

i looked at public AMDIL llvm branch and it has the following lines:

unsigned TrivialRegAlloc::getPhysicalRegister()

{

for (unsigned i = 0; i < _regInUse.size(); ++i) {

if (!_regInUse) {

_regInUse = 1;

return _regSet;

}

}

// No physical register available. Has to spill.

// TODO: add spiller

abort();

return 0;

}

I do not know if support for spilling registers in the AMD pipeline is on the horizon but the ability to spill would really halp to be able to compile cycles on AMD harware.

Additionally the ability to control the ammount of registers the compiler is able to allocate would further allow the program to benefit of GCN

himanshu_gautam
Grandmaster

Re: Blender Cycles(Opencl on AMD GPUS)

Thanks for the feedback. I will let the relevant people know.

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tommie
Journeyman III

Re: Blender Cycles(Opencl on AMD GPUS)

Any developments on this topic yet?

I think this topic should get high priority within the AMD development. AMD and thus almost all Apple users are unable to use these powerful features in blender!

Thanks for the update!

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himanshu_gautam
Grandmaster

Re: Blender Cycles(Opencl on AMD GPUS)

The issue is being undertaken at high priority. Currently i have nothing to share publicly. I will ask for the status again. Thanks for your patience.

cusa123
Adept I

Re: Blender Cycles(Opencl on AMD GPUS)

Check I have a problem with LuxRender and smallluxgpu and luxvr the issue of vram the graphics and I have a 2 gb amd 7870 but apparently never releases memory in linux I always get different values ​​of vram available from 1480-600 mb or less./////

Consulta tengo un problema con luxrender y smallluxgpu y luxvr  el tema de la memoria vram de la grafica y tengo una amd 7870 de 2 gb pero al parecer nunca libera la memoria en linux siempre me aparece valores distintos disponibles de vram desde 1480 hasta 600 mb o menos.

nou
Exemplar

Re: Blender Cycles(Opencl on AMD GPUS)

OpenCL memory size under Linux is currently limited to 50% of total VRAM.

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cusa123
Adept I

Re: Blender Cycles(Opencl on AMD GPUS)

Well the first thing is that the vram on the gpu to use is not released also see time this is my pc..

(((((((Amd fx 8120 , 16gb de ram 1600, cooler telmaltake water performer 2.0 ,fuente cooler master gx 750, gabinete gladiador 600 cooler master ,disco sata 2 wd windows /sata 3 linux ubuntu/ placa asus m5a88-m/ gpu asus amd hd 7870 2gb monitor viewsonic 22((posible coneccion de tv led 32"))))))))))

http://subefotos.com/ver/?668c868936454 ... 73590o.png ((mem 277 mb - 1601 mb)) In windows 7 ((2048 mb vram))

http://subefotos.com/ver/?0a076891d2ebe ... fb21bo.png ((mem 169 mb - 1572 mb)) It makes no sense and are just minutes apart from each other can not consume both while some also use 169-277 mb?

http://subefotos.com/ver/?9ffee225147a9 ... b12c0o.png

The problem is that most renders and less memory do I have, so I have to restart the pc.  ((( Catalyst 13.6 and the same problem with 13.4 and 13.1))


LuxRender forum response!!

It is a very strange problem but it is clearly a driver bug: an application can not have a side effect on GPU memory after the end of the execution (i.e. across multiple executions). What driver version are you using ? Have you tried to install the latest drivers from http://www.amd.com ? I have never seen a problem like that.

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areandres
Journeyman III

Re: Blender Cycles(Opencl on AMD GPUS)

Hi there AMD Team,

i chaned from NVIDIA to AMD because of the very good openCL performance.

But nearly one year the driver have a big compiling bug. I can not use GPU accelerated rendering in Blender Cycles and Luxrender.

Because of errors.

How is the actual status about this BUG. Sorry but this is very poor from such a big company.

Please give us a feedback how the actual status is.

Greets AREANDRES

cusa123
Adept I

Re: Blender Cycles(Opencl on AMD GPUS)

It is possible to generate a hybrid gpu to cpu cycles? It could be possible? that the calculation of the mass is light and is calculated by gpu cpu and the rest in if I'm dividing tary technical but fucionar could not. At this point I think Amd and years that have already passed do not think amd has not some company that is targeted towards creating some render engine for amd or its range of graphics. But I also know that after more than 1 year without a solution I think will give not so I think it would be better to start from scratch to create one or the other option is that if possible with a company that works together as business amd Square Enix's games and his Crystal dinamic. The other option is to get more people interested in the issue, but the question is a bad idea as it will not be any competition and to companies or communities or individuals in the last two feedstock giving amd or amd gpus Pc Amd thus also expands the idea and more users for example. The idea also is to solutions not only short term but also if the big question amd anyone know the answer is as you may want to win some kind of market Apple if your graphic example only works on a particular type of programs and nothing more ?. Also we're reading that Nvidia and sack or was that for a driver with OpenGL 4.4 the question is how long it took to get him out Amd 1 years? or months? if so some things in their driver amd deverian to change drastically.

Español

Es posible generar un hibrido de cpu + gpu para cycles? Podria ser una posible? que el calculo de la masa sea y luz sea calculada por gpu y el resto por cpu, en si dividir tares no soy tecnico pero se pudiera fucionar no. A estas alturas creo que Amd y años que ya han pasado no se que pensar de amd tampoco ha alguna empresa que se destinara a crear algun motor de render para amd o su gama de graficas. Pero tambien se que luego de mas de 1 año sin una solucion me parece que no la daran asi que pienso que seria mejor empezar a crear uno de cero o la otra opcion es que si es posible con alguna empresa que colabora amd en conjunto como empresas de juegos  la  Square enix y su Crystal dinamic. La otra opcion es captar  mas gente interesada en el asunto pero la pregunta es el como no sera mala idea algun concurso y para empresas o comunidades o particulares en los dos ultimos regalando materia prima de amd Pc amd o gpus Amd asi tambien se expande la idea y mas usuarios  por ejemplo. La idea tambien es poner soluciones no solo a corto si tambien  largo plazo pero la gran pregunta que nadie de amd sabe contestar es como es posible querer conquistar algun tipo de mercado ejemplo  Apple si tu grafica solo funciona en un tipo particular de programas y nada mas?. Tambien ya estamos leyendo que Nvidia ya saco o esta en eso un driver con opengl 4.4 la pregunta es cuanto tiempo tardara Amd en sacarlo 1 año? o meses ? si es asi algunas cosas de amd en sus driver deverian de cambiar drasticamente.

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