ipex-llm/docs/mddocs/PythonAPI/PyTorch-API.md
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Co-authored-by: ATMxsp01 <shou.xu@intel.com>
2024-06-21 17:15:05 +08:00

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# IPEX-LLM PyTorch API
## Optimize Model
You can run any PyTorch model with `optimize_model` through only one-line code change to benefit from IPEX-LLM optimization, regardless of the library or API you are using.
### `ipex_llm.optimize_model`_`(model, low_bit='sym_int4', optimize_llm=True, modules_to_not_convert=None, cpu_embedding=False, lightweight_bmm=False, **kwargs)`_
A method to optimize any pytorch model.
- **Parameters**:
- **model**: The original PyTorch model (nn.module)
- **low_bit**: str value, options are `'sym_int4'`, `'asym_int4'`, `'sym_int5'`, `'asym_int5'`, `'sym_int8'`, `'nf3'`, `'nf4'`, `'fp4'`, `'fp8'`, `'fp8_e4m3'`, `'fp8_e5m2'`, `'fp16'` or `'bf16'`, `'sym_int4'` means symmetric int 4, `'asym_int4'` means asymmetric int 4, `'nf4'` means 4-bit NormalFloat, etc. Relevant low bit optimizations will be applied to the model.
- **optimize_llm**: Whether to further optimize llm model.
Default to be `True`.
- **modules_to_not_convert**: list of str value, modules (`nn.Module`) that are skipped when conducting model optimizations.
Default to be `None`.
- **cpu_embedding**: Whether to replace the Embedding layer, may need to set it to `True` when running BigDL-LLM on GPU on Windows.
Default to be `False`.
- **lightweight_bmm**: Whether to replace the `torch.bmm` ops, may need to set it to `True` when running BigDL-LLM on GPU on Windows.
Default to be `False`.
- **Returns**: The optimized model.
- **Example**:
```python
# Take OpenAI Whisper model as an example
from ipex_llm import optimize_model
model = whisper.load_model('tiny') # Load whisper model under pytorch framework
model = optimize_model(model) # With only one line code change
# Use the optimized model without other API change
result = model.transcribe(audio, verbose=True, language="English")
# (Optional) you can also save the optimized model by calling 'save_low_bit'
model.save_low_bit(saved_dir)
```
## Load Optimized Model
To avoid high resource consumption during the loading processes of the original model, we provide save/load API to support the saving of model after low-bit optimization and the loading of the saved low-bit model. Saving and loading operations are platform-independent, regardless of their operating systems.
### `ipex_llm.optimize.load_low_bit`_`(model, model_path)`_
Load the optimized pytorch model.
- **Parameters**:
- **model**: The PyTorch model instance.
- **model_path**: The path of saved optimized model.
- **Returns**: The optimized model.
- **Example**:
```python
# Example 1:
# Take ChatGLM2-6B model as an example
# Make sure you have saved the optimized model by calling 'save_low_bit'
from ipex_llm.optimize import low_memory_init, load_low_bit
with low_memory_init(): # Fast and low cost by loading model on meta device
model = AutoModel.from_pretrained(saved_dir,
torch_dtype="auto",
trust_remote_code=True)
model = load_low_bit(model, saved_dir) # Load the optimized model
```
```python
# Example 2:
# If the model doesn't fit 'low_memory_init' method,
# alternatively, you can obtain the model instance through traditional loading method.
# Take OpenAI Whisper model as an example
# Make sure you have saved the optimized model by calling 'save_low_bit'
from ipex_llm.optimize import load_low_bit
model = whisper.load_model('tiny') # A model instance through traditional loading method
model = load_low_bit(model, saved_dir) # Load the optimized model
```