NVLink Performance

[ronnyhatteland]

I ordered a NVLink for my 2 x 2080TI cards in hope of increasing the render performance or at least reducing the total memory usage.

So far it seems that performance was reduced by 4% and it didn't seem to do much in terms of memory usage, around 500MB less of 13GB total usage on both cards - is this normal?

[Stephen.Blair]

I think NVLink is about having more memory available, so you can render bigger scenes with more textures. It won't reduce memory usage.

[ronnyhatteland]

Thank you for the answer, but I still don't understand. When I render without the NVLink the memory usage is distributed evenly between both cards, let's say 7GB each. When I render with NVLink they still use 7GB each and the upper limit would still be 11GB on each card?

[104906471]

why I can not use nvlink ? u can see my question,PLZ give me some help.

[104906471]

plz see my question:<a href="https://answers.arnoldrenderer.com/comments/16105/view.html">click me</a> 
https://answers.arnoldrenderer.com/comments/16105/view.html

[Christoph_Schaedl]

With nvlink the upper limit will be 22GB.

[ronnyhatteland]

If the cards use just as much memory each with and without NVLink, how can I then render bigger scenes with more textures?

I thought the whole point was to share the memory between the GPUs so you don't have memory duplication on each GPU?

Am I supposed to see the presence of the NVLink in nvidia-smi?

[thiago.ize · Accepted solution]

Sharing memory has a speed hit so we don't share memory until the GPU runs out of memory. Keep adding more textures and other data to your scene and eventually you'll see nvlink lets it render while not using nvlink results in an out of memory error.

[ronnyhatteland]

Ah OK, that makes sense, thank you for the answer.