ml-explore / ml-explore/mlx-examples

Huge memory usage when finetuning

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Python
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Description

When fine-tuning Mistral 7B in 4-bit quantization (qlora), I'm seeing huge memory usage (160GB VRAM)

Parameters used:

  • --batch-size 1
  • --lora-layers 16

The dataset is composed of around 1200 entries. No entry is longer than 7500 tokens, some are significantly shorter, most are right in the middle.

If I reduce --lora-layers to 4, the memory usage peaks at around 30GB, but the end result is very poor quality.

Is this sort of memory usage expected?

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Research direction

Start by reproducing fine-tuning with Mistral 7B in 4-bit QLoRA using batch size 1 and 16 LoRA layers, then compare memory usage with 4 layers. Trace the fine-tuning entry point and configuration handling to identify what scales with sequence length and LoRA layer count; done means explaining whether the 160GB peak is expected or isolating a reproducible memory problem.

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Assessment

Tech stack
python
Domain
machine-learning
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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