The OLLAMA_MAX_VRAM env var was a temporary workaround for OOM
scenarios. With Concurrency this was no longer wired up, and the simplistic
value doesn't map to multi-GPU setups. Users can still set `num_gpu`
to limit memory usage to avoid OOM if we get our predictions wrong.
Still not complete, needs some refinement to our prediction to understand the
discrete GPUs available space so we can see how many layers fit in each one
since we can't split one layer across multiple GPUs we can't treat free space
as one logical block
This change adds support for multiple concurrent requests, as well as
loading multiple models by spawning multiple runners. The default
settings are currently set at 1 concurrent request per model and only 1
loaded model at a time, but these can be adjusted by setting
OLLAMA_NUM_PARALLEL and OLLAMA_MAX_LOADED_MODELS.
