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c13737d | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | # Big model inference benchmarks
Running inference with Accelerate on big models.
## Setup
These benchmarks use the `transformers` library:
```bash
pip install transformers
```
To reproduce or test a new setup, run
```py
python inference_acc.py model_name
```
This script supports `gpt-j-6b`, `gpt-neox`, `opt` (30B version) and `T0pp` out of the box, but you can specify any valid checkpoint for `model_name`.
To force a different `torch_dtype` than the one in the config: `--torch_dtype xxx`.
If you get an error linked to disk offload, you need to add the option `--disk-offload`
## Results
On a setup with two Titan RTXs (24GB of RAM) and 32GB of RAM, we get the following benchmarks (T0pp does not run in float16, which is why it's not included).
| Model | Model load time | Generation time | dtype | GPU 0 use | GPU 1 use | CPU use | Disk offload |
|:-----:|:---------------:|:---------------:|:-----:|:---------:|:---------:|:-------:|:------------:|
| GPT-J-6B | 8.7s | 0.05s per token | float16 | 11.7GB | 0GB | 0GB | no |
| GPT-J-6B | 12.4s | 0.06s per token | float32 | 21.9GB | 1.5GB | 0GB | no |
| GPT-Neo-X-20B | 30.9s | 0.08s per token | float16 | 21.5GB | 18GB | 0GB | no |
| GPT-Neo-X-20B | 78.2s | 10.72s per token | float32 | 20.3GB | 22.7 GB | 24.4GB | yes |
| T0pp (11B) | 29.4s | 0.05s per token | float32 | 21.1GB | 21.3GB | 0GB | no |
| OPT-30B | 34.5s | 2.37s per token | float16 | 20.7GB | 22.3GB | 14.1GB | no |
| OPT-30B | 112.3s | 33.9s per token | float32 | 20.2GB | 21.2GB | 23.5GB | yes |
Note on the results:
- using two GPUs instead of one does not slow down generation
- using CPU offload slows down a bit (see OPT-30b)
- using disk offload slows down a lot (need to implement prefetching)
You will also note that Accelerate does not use anymore GPU and CPU RAM than necessary:
- peak GPU memory is exactly the size of the model put on a given GPU
- peak CPU memory is either the size of the biggest checkpoint shard or the part of the model offloaded on CPU, whichever is bigger. |