That makes sense. The title initially sounded like a general llama.cpp speedup on Apple Silicon, but if the improvement comes from fixing kernel selection inside Virtualization.framework VMs, that distinction is pretty important.
> this won't speed up llama.cpp for everyone, just for users running it in this particular kind of Virtualization.framework VM.
correct. these figures apply to llama.cpp inside the macOS guest configuration we tested. Lume is the VM frontend we used, while Apple's Virtualization.framework provides the virtual GPU. bare-metal llama.cpp is unaffected.
> The fix here works around a problem where the VM was causing llama.cpp to select the wrong kernels.
mostly, with one nuance: llama.cpp is selecting the correct kernels for the capability answers it receives. the stock guest reports an older Apple GPU family and a 32 KB threadgroup memory limit, so llama.cpp chooses slower kernels. Our process-scoped layer reports the tested Apple 9 and 64 KB values while allowing llama.cpp to select newer paths that the paravirtual GPU successfully execute
the layer itself though works at the Metal API boundary, independently of llama.cpp. other Metal compute and graphics apps now may select newer paths from the same capability answers, although this is still preliminary and each app needs separate testing. for example, MLX-LM stayed flat in our tests
yeah fair point. it's always tricky to get the whole idea across within HN's title limit. tldr: we ran the same workload in the same Lume macOS VM on the same Apple Silicon host, first with stock Metal capability reporting and then with our process-scoped dynamic library. The 11.08x figure is prompt processing, while 16.36x is token generation. the mechanism technically extends to graphics workloads too but these figures are specifically from llama.cpp
So those generation numbers aren't really anchored to Apple's hardware designs. It's just counting from when Apple introduced the Metal API, and the first several generations were when the GPU cores Apple was using were still nominally PowerVR designs.
What hardware do you run? I have a first-gen mac studio, and I just run cmake and build with no special options. Same thing with llama-server, I just specify the model and use the built-in web UI.
For reference, I get ~26 tok/sec with the new Muse 30B model.
An M1 Max MBP manages roughly 10 tok/sec without the Dflash speculative draft support so that tracks; the M1 Max apparently has trouble actually saturating its memory bandwidth.
There are certainly challenges. When setting up a new model, I get AI to walk me through the commands using llama-benchmark that determine the best parameters for my particular configuration and needs. Once you've got that it's pretty easy to port those parameters to llama-server. It takes me about an hour to run through this process. It would be great if there was a registry of hardware, models, configuration parameters, and resulting tokens per second. Maybe one day we'll get there.
What kind of parameters do you end up changing, and how much difference does it make. Perhaps I am missing something and get more tok/sec, but I usually just do a git pull, then rebuild the latest whenever I get a new model.
In the past, I had to play with chat templates for some models to work with agents for tool calling. But I've never had to do anything other than specify the model, and tweaking the context size in some cases.
The fix here works around a problem where the VM was causing llama.cpp to select the wrong kernels.
correct. these figures apply to llama.cpp inside the macOS guest configuration we tested. Lume is the VM frontend we used, while Apple's Virtualization.framework provides the virtual GPU. bare-metal llama.cpp is unaffected.
> The fix here works around a problem where the VM was causing llama.cpp to select the wrong kernels.
mostly, with one nuance: llama.cpp is selecting the correct kernels for the capability answers it receives. the stock guest reports an older Apple GPU family and a 32 KB threadgroup memory limit, so llama.cpp chooses slower kernels. Our process-scoped layer reports the tested Apple 9 and 64 KB values while allowing llama.cpp to select newer paths that the paravirtual GPU successfully execute
the layer itself though works at the Metal API boundary, independently of llama.cpp. other Metal compute and graphics apps now may select newer paths from the same capability answers, although this is still preliminary and each app needs separate testing. for example, MLX-LM stayed flat in our tests
historically related limitations have been coming up across Apple Silicon VM frontends for a while e.g. Tart tracked MPS/GPU support back in 2023: - https://github.com/openai/tart/issues/501 - https://github.com/openai/tart/issues/1032
UTM also has related cases where apps detect the Apple paravirtual Metal device but falls back to software rendering: https://github.com/utmapp/UTM/issues/7671
So this was the comparison, for me the title was a bit confusing
I wonder if their work is related?
For reference, I get ~26 tok/sec with the new Muse 30B model.
In the past, I had to play with chat templates for some models to work with agents for tool calling. But I've never had to do anything other than specify the model, and tweaking the context size in some cases.
Yeah not doing that