Standard llama.cpp can mmap the gguf, so it'll stay on disk if it doesn't fit on memory, and the kernel page cache will ensure the hot parts ("resident trunk") stay resident. What's the benefit of a custom implementation at all?
Letting the kernel use SSD based swap space for something this big would be a good way to destroy its cumulative write endurance over a period of just a couple months. I would be very interested in seeing SMART self reported drive cumulative write and wear out stats if this was done for more than a short test. In my experience llama-server is better run with --no-mmap on things that will fit entirely into RAM. Though…
Optanes are a good option here, right?
I bought mine for $100 for each 128GB DDR4 stick. I believe write performance is off-the-charts on these, besides the fact they're c-h-e-a-p.