Lightning-AI / Lightning-AI/lit-llama
How to use deepspeed zero-3-offload strategy correctly? (Parameters Duplication Issue)
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Description
Hi, I wonder how to write the code for using the deepspeed zero-3-offload strategy correctly. Currently, my code looks like:
```
from lightning.fabric.strategies import DeepSpeedStrategy
deep_speed = DeepSpeedStrategy(
stage=3,
offload_optimizer=True,
offload_parameters=True,
)
fabric = L.Fabric(accelerator="gpu", devices=num_devices,strategy=deep_speed)
```
However, it seems the parameters are duplicated for all gpu. I attached the screenshot to show the GPU utilization after `model, optimizer = fabric.setup(model, optimizer)`:
According to my understanding, the parameters should be distributed on different devices, right?
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Research direction
Start with the shown DeepSpeedStrategy configuration and the call to fabric.setup(model, optimizer). Reproduce the reported GPU utilization and inspect how parameters are allocated across devices after setup. Done means the behavior is explained and the documented or corrected configuration prevents unintended parameter duplication.
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Assessment
- Tech stack
- python
- Domain
- distributed-systems, machine-learning
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100