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In a traditional render farm that's not an issue. As the new supercomputing centres have shown, there's a huge push to add massive amounts of GPU power to these

In a traditional render farm that's not an issue. As the new supercomputing centres have shown, there's a huge push to add massive amounts of GPU power to these because it's more cost effective. I'm not saying GPU rendering is easy, it's way harder to do correctly because of memory constraints, but the performance of GPUs over CPUs (compute per watt, compute total) is a gap that's only getting wider. It's easy to add a few thousand more shaders, just add another card. Not easy to strap on another 12-core chip, you need to engineer from the ground up for that. A GPU also has access to all system memory via DMA, so that shouldn't be an issue. It's just going to be hard to coordinate that data transfer in a performant way.

berkut 12y ago
In a traditional render farm that is an issue, as the vast majority of renderfarms for VFX companies are CPU only. renderfarms aren't just using for renderer rendering, they're used for comp rendering, fluid sims (often using up to 96 GB of RAM), physics sims, etc. Very little of this is GPU-based currently. Where GPUs are starting to be used is on the artist workstation to speed up iteration/preview time. But not on renderfarms. GPU memory access across the PCIE bus is ridiculously slow for smaller jobs. It's often the case that the slower CPU can do the work before the cumulative time of copy data to GPU, get GPU to do work, then copy it back again has been done. For longer jobs of smaller data, GPUs make sense. GPUs also have much higher power draw than CPUs and produce much more heat, which is a huge issue for renderfarms with close to 100% utilisation at crunch time.