Jonathan Mack

AFAIK, that's not a feature of USD

I don't think so, as that checkbox effectively makes it into a single task

jlait
If you want to cap VRAM consumption you can use Edit::Copernicus Settings::Video Ram. By default we will use all of your VRAM before we start evicting stuff to RAM. For compositing you may get away with a low value for this - the high value is to avoid things like Pyro from swapping.

We don't convert to RGBA in memory - it may look like that because the nodes all operate on RGBA, but they are doing just-in-time widening; so the memory use of a Mono channel is just one mono value. However, we DO operate on 32bit float by default, so that is 4x the memory of a 8-bit image.

An important optimization we don't do yet is to throw away the results that are no longer needed. Currently every COP node keeps its output, which adds up quickly at 4k. This means you can walk the network without recooking; but that is cold comfort when you've run out of memory.

How is memory managed on platforms with unified memory? With no main memory to evict to, is that setting used at all? Is there any unnecessary copying of layer data when moving from cpu to gpu compute? I'm finding even with 128GB of unified memory, it can be pretty constraining, I can't imagine what it's like with only 16GB of VRAM.