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[Sidefx-houdini-list] open cl and quadro on h12
Thursday, 16 August 2012 Thu, 16 Aug '12
On 08/16/2012 04:44 PM, crydalch at sidefx.com wrote:
On whether the GPU and CPU versions produce the same results, they should as both are using OpenCL. From the Pyro 2 description: / "The hardware acceleration uses OpenCL, which is compatible with the OpenCL library on the CPU. This means that a simulation prototype performed using the GPU one the workstation _will produce identical results _if run non-interactively on a headless farm."/Hmm, well that's only true if the CPU simulation is actually using the OpenCL CPU driver, rather than just turning off the "Use OpenCL" option, which will take a completely different, non-OpenCL code path. From my experience the OpenCL / non-OpenCL sims are fairly close in appearance, however. Even if you are using an OpenCL CPU driver on the farm, you still might get slightly different results due to different ordering of floating point instructions. So for example, if you prototype on a workstation with an NVIDIA GPU, then run the same simulation on the AMD CPU driver on the farm, you'll be using the same code but compiled with two different compilers, essentially. So the results should be very similar, but probably not exactly identical due to possibly different instruction ordering (which is probably what the documentation should say, FWIW).