0199407d93
* notes about performance and some performance improvements (don't update the display for every token) * swift-format * Update Applications/LLMEval/README.md Co-authored-by: Awni Hannun <awni.hannun@gmail.com> * Update Applications/LLMEval/README.md Co-authored-by: Awni Hannun <awni.hannun@gmail.com> --------- Co-authored-by: Awni Hannun <awni.hannun@gmail.com>
59 lines
2.3 KiB
Markdown
59 lines
2.3 KiB
Markdown
# LLMEval
|
|
|
|
An example that:
|
|
|
|
- downloads a huggingface model (phi-2) and tokenizer
|
|
- evaluates a prompt
|
|
- displays the output as it generates text
|
|
|
|
> Note: this _must_ be built Release, otherwise you will encounter
|
|
stack overflows.
|
|
|
|
You will need to set the Team on the LLMEval target in order to build and
|
|
run on iOS.
|
|
|
|
Some notes about the setup:
|
|
|
|
- this downloads models from hugging face so LLMEval -> Signing & Capabilities has the "Outgoing Connections (Client)" set in the App Sandbox
|
|
- LLM models are large so this uses the Increased Memory Limit entitlement on iOS to allow ... increased memory limits for devices that have more memory
|
|
- `MLX.GPU.set(cacheLimit: 20 * 1024 * 1024)` is used to limit the buffer cache size
|
|
- The Phi2 4 bit model is small enough to run on some iPhone models
|
|
- this can be changed by editing `let modelConfiguration = ModelConfiguration.phi4bit`
|
|
|
|
### Trying Different Models
|
|
|
|
The example application uses Phi2 model by default, see [ContentView.swift](ContentView.swift#L58):
|
|
|
|
```
|
|
/// this controls which model loads -- phi4bit is one of the smaller ones so this will fit on
|
|
/// more devices
|
|
let modelConfiguration = ModelConfiguration.phi4bit
|
|
```
|
|
|
|
There are some pre-configured models in [LLM/Models.swift](../../Libraries/LLM/Models.swift#L62)
|
|
and you can load any weights from Hugging Face where there
|
|
is a model architecture defined and you have enough
|
|
memory.
|
|
|
|
### Troubleshooting
|
|
|
|
If the program crashes with a very deep stack trace you may need to build
|
|
in Release configuration. This seems to depend on the size of the model.
|
|
|
|
There are a couple options:
|
|
|
|
- build Release
|
|
- force the model evaluation to run on the main thread, e.g. using @MainActor
|
|
- build `Cmlx` with optimizations by modifying `mlx/Package.swift` and adding `.unsafeOptions(["-O3"]),` around line 87
|
|
|
|
Building in Release / optimizations will remove a lot of tail calls in the C++
|
|
layer. These lead to the stack overflows.
|
|
|
|
See discussion here: https://github.com/ml-explore/mlx-swift-examples/issues/3
|
|
|
|
### Performance
|
|
|
|
Different models have difference performance characteristics. For example Gemma 2B may outperform Phi-2 in terms of tokens / second.
|
|
|
|
You may also find that running outside the debugger boosts performance. You can do this in Xcode by pressing cmd-opt-r and unchecking "Debug Executable".
|