abstrax wrote:The statistics in the viewport don't show the memory that is available by using the other GPU. You will have to run out of memory first to notice the usage of the other GPU's memory.
The reason is that accessing memory from a different GPU (via NVlink) is still slower than accessing memory directly from the GPU that is processing it. So to maximize performance we maximize the amount of stuff we store on the GPU first, before we are starting to share data between GPUs. It's kind of similar to the way how out-of-core memory works, where we also try to max out the GPU first before we start using host memory.
When you start using peer-to-peer memory, you will see a blue "overflow" bar in the statistics and the peer-to-peer memory usage in the GPU stats of the viewport.
Also please be aware that NVlink doesn't just magically makes one large memory out of of two smaller ones. There is a bunch of logic in Octane that deals with memory distribution and we have to treat peer-to-peer memory specially.
I just tried myself, gave myself NVlink under the christmas tree, LOL...and found out its not showing 22GB of VRAM....
Anyway, what does the bolded mean exactly? I dont think its really that important if its magic, or not, how it happens, the most important part is, do we get access to double the VRAM or not? Can we get some more info about what to expect, i mean regarding max available VRAM capacity and speed? If it is slower, by how much exactly? Since its being in use, when needed, am i fine to have it switched on by default and not get any performance penalty then?
The other thing, can be something done with the VRAM taken by the system itself, at last? I mean only 9GB available out of 11, what is this? I remember it used to be far less pre-Windows 10... can you please something do about it? I could accept 500 MB, 1GB maybe...but 2? Why, to what purpose?
Merry Christmas everyone!
R9 7950x, 64GB DDR5 6000 MHz, 2x RTX 4090, Samsung 990 Pro 2TB, Kingston KC3000 2TB, Kingston KC3000 1TB, WD Caviar Gold 6TB, Win11 Pro 64bit