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64 lines
2.0 KiB
Markdown
64 lines
2.0 KiB
Markdown
>FlexGen is a high-throughput generation engine for running large language models with limited GPU memory (e.g., a 16GB T4 GPU or a 24GB RTX3090 gaming card!).
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https://github.com/FMInference/FlexGen
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## Installation
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No additional installation steps are necessary. FlexGen is in the `requirements.txt` file for this project.
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## Converting a model
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FlexGen only works with the OPT model, and it needs to be converted to numpy format before starting the web UI:
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```
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python convert-to-flexgen.py models/opt-1.3b/
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```
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The output will be saved to `models/opt-1.3b-np/`.
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## Usage
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The basic command is the following:
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```
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python server.py --model opt-1.3b --flexgen
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```
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For large models, the RAM usage may be too high and your computer may freeze. If that happens, you can try this:
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```
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python server.py --model opt-1.3b --flexgen --compress-weight
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```
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With this second command, I was able to run both OPT-6.7b and OPT-13B with **2GB VRAM**, and the speed was good in both cases.
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You can also manually set the offload strategy with
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```
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python server.py --model opt-1.3b --flexgen --percent 0 100 100 0 100 0
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```
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where the six numbers after `--percent` are:
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```
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the percentage of weight on GPU
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the percentage of weight on CPU
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the percentage of attention cache on GPU
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the percentage of attention cache on CPU
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the percentage of activations on GPU
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the percentage of activations on CPU
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```
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You should typically only change the first two numbers. If their sum is less than 100, the remaining layers will be offloaded to the disk, by default into the `text-generation-webui/cache` folder.
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## Performance
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In my experiments with OPT-30B using a RTX 3090 on Linux, I have obtained these results:
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* `--flexgen --compress-weight --percent 0 100 100 0 100 0`: 0.99 seconds per token.
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* `--flexgen --compress-weight --percent 100 0 100 0 100 0`: 0.765 seconds per token.
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## Limitations
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* Only works with the OPT models.
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* Only two generation parameters are available: `temperature` and `do_sample`. |