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Parameter-efficient fine-tuning

As explained in Building Reliable AI Systems

Fine-tuning methods that adapt a small subset or representation of a model’s parameters to reduce training resource requirements.

Full fine-tuning can demand substantial GPU memory and computation, and updating every weight risks catastrophic forgetting. Parameter-efficient fine-tuning (PEFT) reduces training demands by adapting only a small fraction of model parameters. section 5.3.3

Two practical PEFT approaches are:

  • LoRA freezes the base model and trains small adapter matrices added to selected model components. section 5.3.3
  • QLoRA extends LoRA and uses less memory; its reported performance is somewhat lower than LoRA’s. section 5.3.3

Fine-tuning is useful for specialized tasks when prompting and retrieval alone are insufficient. High-quality, well-formatted training data remains important; combining fine-tuning with retrieval can provide live knowledge access alongside consistent reasoning. section 5.5

Table 5.2 Comparing different fine-tuning methods
Method
Parameter efficiency
Performance
Memory usage
When to choose
Full fine-tuning
Lowest (100%)
Highest
Highest
When you have multiple high-end GPUs and need maximum adaptation
LoRA
High (~0.1–1%)
Very high (95–99% of full)
Low
When you have a decent GPU and need strong performance
QLoRA
High (~0.1–1%)
High (90–95% of full)
Lowest
When you have limited GPU resources but need to fine-tune large models

Compare parameter efficiency, performance, memory use, and hardware guidance when choosing between full fine-tuning, LoRA, and QLoRA. section 5.3.3

How Building Reliable AI Systems covers it

How deep it goes
Explains LoRA’s frozen base and trainable adapters, then compares LoRA and QLoRA by parameter efficiency, performance, and memory.
Examples
Compares full fine-tuning, LoRA, and QLoRA across parameter share, performance, memory, and hardware choice.
What you can do after
Apply LoRA or QLoRA to fine-tune large models with reduced training-resource demands.
How it connects
Links PEFT to full fine-tuning, LoRA, QLoRA, prompting, and retrieval-augmented generation.

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This explainer was generated by Manning's knowledge graph from the text of Building Reliable AI Systems. The section links point to the parts of the book it draws on.