How to Fine Tune LLM for Maximum Performance (Step-by-Step Guide)

Learn how to fine tune LLMs with this step-by-step guide to maximize their accuracy and efficiency.

· 14 min read
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With the latest advancements in Large Language Models, including multimodal LLM, you may feel pressure to get your large language model up and running. The challenge is that these models sometimes perform poorly out of the box. The performance can vary depending on the specific task you want to accomplish. For example, suppose you want to use a large language model to generate product descriptions for an e-commerce site. In that case, there’s a good chance that the content generated without customization will be generic and not aligned with your brand. Fine-tuning the model to understand your products and e-commerce site better will lead to better results.

How do you get started? This article'll explore fine-tuning LLM to achieve maximum performance tailored to specific tasks, ensuring accuracy, efficiency, and scalability without unnecessary complexity. Lamatic's generative AI tech stack makes this process easier and allows you to customize the model to fit your unique goals.

What is LLM Fine Tuning and Its Importance

Processes - How to Fine Tune LLM

Large language models (LLMs) have transformed the field of natural language processing with their advanced capabilities and highly sophisticated solutions. These models, trained on massive text datasets, perform a wide range of tasks, including:

  • Text generation
  • Translation
  • Summarization
  • Question answering

But while LLMs are powerful tools, they’re often incompatible with specific tasks or domains. 

Fine-tuning allows users to adapt pre-trained LLMs to more specialized tasks. By fine-tuning a model on a small task-specific dataset, you can improve its performance on that task while preserving its general language knowledge. For example, a Google study found that fine-tuning a pre-trained LLM for sentiment analysis improved its accuracy by 10 percent.

What is Fine-Tuning?  

Fine-tuning is the process of adjusting the parameters of a pre-trained large language model to a specific task or domain. Although pre-trained language models like GPT possess vast language knowledge, they need more specialization in specific areas. Fine-tuning addresses this limitation by allowing the model to learn from domain-specific data to make it more accurate and effective for targeted applications. 

Exposing the model to task-specific examples during fine-tuning can help it better understand the domain's nuances. This bridges the gap between a general-purpose language model and a specialized one, unlocking the full potential of LLMs in specific domains or applications.

Why Fine-Tune LLMs?  

Generally, you might want to fine-tune LLMs if you have the following requirements:

Customization  

Every domain or task has unique language patterns, terminologies, and contextual nuances. You can customize a pre-trained LLM by fine-tuning it to understand these unique aspects better and generate content specific to your domain. This approach allows you to tailor the model's responses to your specific requirements, ensuring that it produces accurate and contextually relevant outputs. Whether it’s: 

  • Legal documents
  • Medical reports
  • Business Analytics
  • Internal company data

When trained on specialized datasets, LLMs offer nuanced expertise in these domains. Customization through fine-tuning empowers you to leverage LLMs' power while maintaining the accuracy necessary for your specific use case.

Data Compliance  

In many industries, such as healthcare, finance, and law, strict regulations govern the use and handling of sensitive information. Organizations can ensure their model adheres to data compliance standards by fine-tuning the LLM on proprietary or regulated data. 

This process allows for the development of LLMs trained specifically on in-house or industry-specific data, mitigating the risk of exposing sensitive information to external models while enhancing the security and privacy of your data.

Limited Labeled Data  

In many real-world scenarios, obtaining large quantities of labeled data for a specific task or domain can be challenging and costly. Fine-tuning allows organizations to leverage pre-existing labeled data more effectively by adapting a pre-trained LLM to the available labeled dataset, maximizing its utility and performance.  

Efficiency  

Training LLMs from scratch demands significant computational resources and time. However, fine-tuning a pre-trained model is often more efficient because it bypasses the initial training stages, allowing for quicker convergence to a solution. By fine-tuning with limited labeled data, organizations can overcome the constraints of data scarcity and still improve the model's accuracy and relevance to the targeted task or domain.

Why Might Your Business Need a Fine-Tuned Model?  

We know that Chat GPT and other language models have answers to many questions. Individuals and companies want their own LLM interface for their private and proprietary data. This is the new hot topic in tech town, especially large language models for enterprises. Here are a few reasons why you might need LLM fine-tuning. 

Specificity and Relevance  

While LLMs are trained on vast amounts of data, they might need to learn the specific terminologies, nuances, or contexts relevant to a particular business or industry. Fine-tuning ensures the model understands and generates highly relevant content.  

Improved Accuracy  

Critical business functions have a slim margin for error. Fine-tuning business-specific data can help achieve higher accuracy levels, ensuring the model's outputs align closely with expectations.  

Customized Interactions  

Fine-tuning helps tailor responses to match your brand's voice, tone, and guidelines if you're using LLMs for customer interactions, like chatbots. This ensures a consistent and branded user experience.  

Data Privacy and Security  

General LLMs might generate outputs based on publicly available data. Fine-tuning allows businesses to control the data the model is exposed to, ensuring that the generated content doesn't inadvertently leak sensitive information.  

Addressing Rare Scenarios  

Every business encounters rare but crucial scenarios specific to its domain. A general LLM might need to handle such cases more optimally. Fine-tuning ensures that these edge cases are effectively catered to. While LLMs offer broad capabilities, fine-tuning sharpens those capabilities to fit the unique contours of a business's needs, ensuring optimal performance and results.

Step-by-Step Guide on How to Fine-Tune LLM

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Preparing Your Dataset for Fine-tuning

Let's explore the fine-tuning process in more detail in LLMs. Many open-source datasets offer insights into user behaviors and preferences when preparing training data, even if they aren't directly formatted as instructional data. 

For example, we can use the large data set of Amazon product reviews to create instruction prompt datasets for fine-tuning. Prompt template libraries include templates for different tasks and datasets. 

Starting the Fine-tuning Process

As with standard supervised learning, you divide your instruction data set into training validation and test splits once it is ready. During fine-tuning, you select prompts from your training data set and pass them to the LLM, generating completions. 

Adjusting the LLMs Weights to Improve Performance

During the fine-tuning phase, when the model is exposed to a newly labeled dataset specific to the target task, it calculates the error or difference between its predictions and the actual labels. The model then uses this error to adjust its weights, typically via an optimization algorithm like gradient descent. 

The magnitude and direction of weight adjustments depend on the gradients, which indicate how much each weight contributed to the error. Weights more responsible for the error are adjusted more, while those less responsible are adjusted less. 

Achieving Task Customization Over Multiple Iterations 

Over multiple iterations (or epochs) of the dataset, the model adjusts its weights, honing in on a configuration that minimizes the error for the specific task. The aim is to adapt the previously learned general knowledge to the nuances and specific patterns present in the new dataset, thereby making the model more specialized and effective for the target task. 

Understanding the Fine-tuning Example

During this process, the model is updated with the labeled data. It changes based on the difference between its guesses and the actual answers. This helps the model learn details found in the labeled data, improving its performance at the task for which it's fine-tuned. 

Let's take an example to illustrate this better: If you ask a pre-trained model, "Why is the sky blue?" It might reply, "Because of the way the atmosphere scatters sunlight." This answer is simple and direct. It might be too brief for a chatbot on a science educational platform. It may need more scientific detail or context based on your guidelines. This is where supervised fine-tuning helps. 

Exploring Fine-tuning Methods

The model can give a more in-depth response to scientific questions. After fine-tuning, when asked, "Why is the sky blue?" the model might provide a more detailed explanation like: "The sky appears blue because of a phenomenon called Rayleigh scattering. As sunlight enters Earth's atmosphere, it consists of different colors, each with its wavelength. Blue light has a shorter wavelength and is scattered in all directions by the gases and particles in the atmosphere. This scattering causes the direct sunlight to appear white, but the sky takes on a blue hue." This enriched response is comprehensive and suitable for a science educational platform. 

Instruction Fine-tuning: Customizing LLMs for Specific Tasks

One strategy used to improve a model's performance on various tasks is instruction fine-tuning. It involves training the machine learning model using examples demonstrating how it should respond to the query. The dataset you use for fine-tuning large language models has to serve the purpose of your instruction. 

For example, suppose you fine-tune your model to improve its summarization skills. In that case, you should build up a dataset of examples that begin with the instruction to summarize, followed by text or a similar phrase. In the case of translation, you should include instructions like “translate this text.” These prompt completion pairs allow your model to "think" in a new niche way and serve the given specific task.

Full Fine-tuning: Updating All Model Weights

Full fine-tuning, instruction fine-tuning in which all of the model's weights are updated, results in a new version of the model with updated weights. It is crucial to note that, just like pre-training, full fine-tuning requires enough memory and compute budget to store and process all the gradients, optimizers, and other components being updated during training. 

Parameter-Efficient Fine-tuning: Reducing Memory Requirements

Training a language model is a computationally intensive task. For a full LLM fine-tuning, you need memory to store the model and the parameters necessary for the training process. Your computer might be able to handle the model weights, but allocating memory for optimizing states, gradients, and forward activations during the training process is a challenging task. Very little hardware can handle this amount of hurdle. 

This is where PEFT is crucial. While full LLM fine-tuning updates every model's weight during the supervised learning process, PEFT methods only update a small set of parameters. This transfer learning technique chooses specific model components and "freezes" the rest of the parameters. 

How PEFT and LoRA Optimize Model Efficiency and Memory Usage

The result logically has a much smaller number of parameters than in the original model (in some cases, just 15-20% of the original weights; LoRA can reduce the number of trainable parameters by 10,000 times). This makes memory requirements much more manageable. PEFT is also dealing with catastrophic forgetting. 

The model remembers the previously learned information since it does not touch the original LLM. Full fine-tuning results in a new version of the model for every task you train on. Each of these is the same size as the original model, so it can create an expensive storage problem if you're fine-tuning for multiple tasks.

Other Types of Fine-tuning: Understanding Task-specific and Multi-task Learning

Let's learn a few more types of learning: 

  • Transfer learning
  • Task-specific fine-tuning
  • Multi-task fine-tuning
  • Sequential fine-tuning

Transfer Learning

Transfer learning is about taking the model that had learned on general-purpose, massive datasets and training it on distinct, task-specific data. This dataset may include labeled examples related to that domain. 

Transfer learning is used when there is not enough data or a lack of time to train data; the main advantage of it is that it offers a higher learning rate and accuracy after training. You can take existing LLMs pre-trained on vast amounts of data, like GPT ¾ and BERT, and customize them for your use case. 

Task-Specific Fine-Tuning

Task-specific fine-tuning is a method where the pre-trained model is fine-tuned on a specific task or domain using a dataset designed for that domain. This method requires more data and time than transfer learning but can result in higher performance on the specific task. For example, translation using a dataset of examples for that task. Good results can be achieved with relatively few examples. 

Catastrophic forgetting happens because the full fine-tuning process modifies the weights of the original LLM. While this leads to great performance on a single fine-tuning task, it can degrade performance on other tasks. For example, while fine-tuning can improve a model's ability to perform certain natural language processing (NLP) tasks like sentiment analysis and result in quality completion, the model may need to remember how to do other tasks. This model knew how to recognize a named entity before fine-tuning correctly identifying it. 

Multi-Task Fine-Tuning

Multi-task fine-tuning is an extension of single-task fine-tuning, where the training dataset consists of example inputs and outputs for multiple tasks. The dataset contains examples instructing the model to perform various tasks, including summarization, review rating, code translation, and entity recognition. You train the model on this mixed dataset to improve its performance on all the tasks simultaneously, thus avoiding the issue of catastrophic forgetting. 

Over many epochs of training, the calculated losses across examples are used to update the model weights. This results in a fine-tuned model that can simultaneously be good at many different tasks. One drawback of multi-task fine-tuned models is that they require a lot of data. You may need as many as 50-100,000 examples in your training set. However, assembling this data can be worthwhile and worthwhile. The resulting models are often competent and suitable for use in situations where good performance at many tasks is desirable. 

Sequential Fine-Tuning

Sequential fine-tuning involves sequentially adapting a pre-trained model to several related tasks. After the initial transfer to a general domain, the LLM might be fine-tuned to a more specific subset. It can be fine-tuned from general language to medical language and from medical language to pediatric cardiology. 

Other Fine-tuning Approaches

Note that there are other fine-tuning examples:

  • Adaptive
  • Behavioral
  • Instruction
  • Reinforced fine-tuning of large language models

These cover some important specific cases for training language models. Fine-tuning approaches are now widely adapted for small language models (SLMs), becoming one of the biggest GenAI trends in 2024. Fine-tuning a small language model is much easier and easier to implement, especially if you’re a small business or a developer looking to improve your model's performance. 

Retrieval Augmented Generation: A Compelling Alternative to Fine-tuning

Retrieval augmented generation (RAG) is a well-known alternative to fine-tuning and combines natural language generation and information retrieval. RAG ensures that language models are grounded by external up-to-date knowledge sources/relevant documents and provides sources. This technique bridges the gap between general-purpose models' vast knowledge and the need for precise, up-to-date information with rich context. RAG is an essential technique for situations where facts can evolve. Grok, the recent invention of xAI, uses RAG techniques to ensure its information is fresh and current. 

Advantages

One advantage of RAG over fine-tuning is information management. Traditional fine-tuning embeds data into the following:

  • Model's architecture
  • Essentially handwriting the knowledge that prevents easy modification.

RAG permits continuous updates in training data and allows data removal/revision, ensuring the model remains current and accurate. In the context of language models, RAG and fine-tuning are often perceived as competing methods. However, their combined use can lead to significantly enhanced performance. Fine-tuning can be applied to RAG systems to identify and improve their weaker components, helping them excel at specific LLM tasks.

LLM FineTuning Challenges & Best Practices

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Fine-tuning can be a long process that needs to be iterated to get it right. Be methodical and explore various options to identify the best setup for your project before you start training your LLM. To ensure successful fine-tuning, consider the following best practices: 

Data Quality and Quantity

The quality of your fine-tuning dataset significantly impacts the model's performance. We all know the sentence: "Garbage In, Garbage Out." Always ensure the data is clean, relevant, and sufficiently large.

Hyperparameter tuning

Fine-tuning is usually a long process that needs to be iterated. Always explore various settings for learning rates, batch sizes, and the number of training epochs to identify the best setup for your project. Precise adjustments are vital to ensuring the model learns efficiently and adapts well to unseen data, avoiding the pitfall of overfitting.

Regular evaluation

Assess the model's progress during training regularly to track its effectiveness and implement required modifications. This involves evaluating the model's performance using a distinct validation dataset throughout the training period. 

Such evaluation is critical for determining the model's performance on the task and its potential for overfitting the training dataset. Based on the outcomes from the validation phase, adjustments can be made as needed to optimize performance.

Fine-Tuning Pitfalls: What to Avoid When Customizing Your LLM

Fine-tuning can sometimes lead to suboptimal outcomes. Be wary of the following pitfalls: 

Overfitting

Using a small dataset for training or overextending the number of epochs can produce overfitting. This is usually characterized by the model showing high accuracy on our training dataset but failing to generalize to new data.

Underfitting

Insufficient training or a low learning rate can result in underfitting, where the model fails to learn the task adequately.

Catastrophic forgetting

When fine-tuning for a particular task, the model might lose the broad knowledge it initially acquired. This issue, called catastrophic forgetting, can diminish the model's ability to perform well across various tasks using natural language processing.

Data leakage

Always ensure that training and validation datasets are separate and there is no overlap, as this can lead to misleading high-performance metrics.

Fine-Tuning vs. RAG: What’s Best for Your Use Case

RAG combines the strengths of retrieval-based models and generative models. In RAG, a retriever component searches an extensive database or knowledge base to find relevant information based on the input query. A generative model then uses this retrieved information to produce a more accurate and contextually relevant response. 

Key benefits of RAG include

Dynamic knowledge integration

Incorporates real-time information from external sources, making it suitable for tasks requiring up-to-date or specific knowledge.

Contextual relevance

The generative model’s responses are enhanced by providing additional context from the retrieved documents.

Versatility

Can handle a wider range of queries, including those requiring specific or rare information that the model may have yet to be trained on. 

Choosing Between Fine-Tuning and RAG

When deciding whether to use fine-tuning or RAG, consider the following factors: 

Nature of the task

Fine-tuning is often the preferred approach for tasks that benefit from highly specialized models (e.g., domain-specific applications). RAG is ideal for tasks that require the integration of external knowledge or real-time information retrieval.

Data availability

Fine-tuning requires a substantial amount of labeled data specific to the task. RAG’s retrieval component can compensate if such data is scarce by providing relevant information from external sources.

Resource constraints

Fine-tuning can be computationally intensive, whereas RAG leverages existing databases to supplement the generative model, potentially reducing the need for extensive training. 

  • LLM vs Generative AI
  • ML vs LLM
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  • Foundation Model vs LLM
  • LLM Quantization
  • Best LLM for Data Analysis
  • Rag vs LLM
  • LLM vs NLP
  • LLM Distillation

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