Agentic AI Notebook
Phase 27

PEFT

~2 min read

Concept & How It Works

  • Key points are in the visual diagram above.

Why Does It Exist?

Standardizes fine-tuning workflows. One API for LoRA, QLoRA, and adapter management across models.

Real-World Analogy

PEFT is a universal adapter kit — fits different appliance brands with the same installation process.
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Visual Workflows

What is PEFT?

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Example

Scenario

Swap customer-support LoRA adapter for sales LoRA adapter on same base model — no redeploy of full weights.

Solution

In Model Engineering (Awareness), apply PEFT to this scenario: Swap customer-support LoRA adapter for sales LoRA adapter on same base model — no redeploy of full weights. Identify the inputs, run the technique, validate the output, and note one thing you would monitor in production.

Practice Task

Do this before moving to the next module — reading alone is not enough.

Open the Code Walkthrough below and run it locally. Change one parameter related to PEFT (e.g. model, temperature, top_k, or tool name), observe the difference in output, and write 2–3 sentences explaining what changed.

Code Walkthrough

Highlighted lines show where PEFT happens in the code.

PEFT
1# PEFT — minimal example2from openai import OpenAI3
4client = OpenAI()  # create API client5
6# Ask the model to explain this topic7response = client.chat.completions.create(  # core API call for PEFT8    model="gpt-4o-mini",9    messages=[10        {"role": "system", "content": "You explain peft clearly."},11        {"role": "user", "content": f"What is peft?"},12    ],13    temperature=0,14)15print(response.choices[0].message.content)  # show output for debugging

Commands to Remember

Commands to Remember

  • pip install peft transformers # LoRA / QLoRA fine-tuning
  • pip install bitsandbytes # quantized training

Common Mistakes

  • Treating PEFT as a black box without evaluation
  • Ignoring cost and latency in production
  • Skipping error handling for peft

Cheat Sheet

Quick recap — the most important points from this module.

Cheat Sheet

quick ref
  • PEFT
  • LoraConfig
  • Adapter Swap