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аналитика - Machine Learning - # Quantization of Large Language Models

Efficient Quantization of Large Language Models Using an Overdetermined Basis Representation


Основные понятия
Kashin Quantization, a novel data quantization approach, can efficiently compress large language models while maintaining competitive or superior predictive performance.
Аннотация

The paper introduces Kashin Quantization, a novel data quantization method that leverages the principles of Kashin representation. The key idea is to decompose any given vector, matrix, or tensor into two factors - the first factor maintains a small infinity norm, while the second exhibits a similarly constrained norm when multiplied by an orthogonal matrix. This representation allows for efficient quantization, as the entries of the factors are well-concentrated around several peaks, enabling them to be replaced with corresponding centroids.

The authors propose a matrix version of the Kashin algorithm, which substantially accelerates computations compared to the naive vector-based approach. They also analyze the theoretical properties of the algorithm and its convergence rate, establishing a connection to the Kolmogorov width.

The authors evaluate Kashin Quantization in the context of next-word prediction tasks and on a set of downstream text classification tasks using language models like OPT, BERT, and RoBERTa. The results demonstrate that Kashin Quantization achieves competitive or superior quality in model performance while ensuring data compression, marking a significant advancement in the field of data quantization.

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Статистика
The proposed Kashin Quantization approach can compress traditional 32-bit floats to low-bit values, reducing data representation size. Kashin Quantization is not only applicable for quantizing Large Neural Networks but also for compressing exchange information, like gradients in Federated Learning and distributed computations.
Цитаты
"Kashin Quantization achieves competitive or superior quality in model performance while ensuring data compression, marking a significant advancement in the field of data quantization." "The method re-imagines data representation by breaking down any data structure into two key factors. The first factor is optimized for a minimal infinity norm, while the second maintains a small infinity norm when post-multiplied by an orthogonal matrix."

Ключевые выводы из

by Daniil Merku... в arxiv.org 04-16-2024

https://arxiv.org/pdf/2404.09737.pdf
Quantization of Large Language Models with an Overdetermined Basis

Дополнительные вопросы

How can Kashin Quantization be extended to handle the quantization of activations in transformer-based language models, which often suffer from large outliers

Kashin Quantization can be extended to handle the quantization of activations in transformer-based language models by leveraging the properties of Kashin representation to address the issue of large outliers. Activations in transformers often exhibit significant variations and outliers, which can pose challenges for quantization. By applying the principles of Kashin Quantization to activations, it is possible to decompose the activation vectors into factors with small infinity norms, similar to the approach used for weight matrices. To handle the quantization of activations, the algorithm can be adapted to focus on clustering the activation values around centroids, similar to how it quantizes weight matrices. By decomposing the activation vectors into two factors with well-concentrated values, the outliers can be effectively mitigated, leading to more efficient quantization. This approach ensures that the quantized activations maintain a balance between reduced bit precision and preserved model performance. Furthermore, incorporating structured orthogonal matrices, such as butterfly matrices or DCT, can enhance the efficiency of the quantization process for activations. These matrices enable faster matvec operations, which can be beneficial for handling the complex computations involved in quantizing transformer activations. By optimizing the choice of orthogonal matrices and refining the clustering process, Kashin Quantization can effectively address the challenges posed by large outliers in transformer activations.

What are the potential limitations or drawbacks of the Kashin Quantization approach, and how can they be addressed

One potential limitation of the Kashin Quantization approach is the variability in convergence rates for different layers of transformer models. As observed in the experiments, not all weight matrices converge efficiently using the Kashin Decomposition algorithm, leading to high quantization errors. To address this limitation, a more robust convergence analysis can be conducted to identify the factors influencing convergence and develop strategies to improve convergence rates for all layers. Another drawback could be the sensitivity of the algorithm to the choice of orthogonal matrices. While structured matrices like butterfly matrices and DCT offer computational advantages, their effectiveness in convergence may vary across different layers. To mitigate this limitation, a more comprehensive study on the impact of orthogonal matrix selection on convergence rates can be conducted, leading to better guidelines for choosing the most suitable matrix for each layer. Additionally, the quantization of activations, which often contain large outliers, may require specialized techniques to ensure accurate representation. Further research can focus on refining the clustering process for activations to handle outliers effectively and improve the overall quantization quality.

How can the theoretical analysis of the Kashin algorithm's convergence rate and its connection to the Kolmogorov width be further developed to provide deeper insights into the method's performance

The theoretical analysis of the Kashin algorithm's convergence rate and its connection to the Kolmogorov width can be further developed to provide deeper insights into the method's performance. By exploring the relationship between the convergence rate of the algorithm and the Kolmogorov width, researchers can gain a better understanding of the algorithm's efficiency and limitations. One avenue for further development is to investigate the impact of different basis vectors on the convergence rate of the Kashin algorithm. By analyzing how the choice of basis vectors influences convergence, researchers can optimize the algorithm for faster and more reliable convergence across various input vectors. Moreover, studying the convergence properties of the algorithm for different classes of orthogonal matrices can provide valuable insights into the effectiveness of each matrix type. By conducting a detailed analysis of convergence rates for various matrices, researchers can identify the most suitable matrices for different layers of transformer models, enhancing the overall performance of Kashin Quantization. Overall, further research on the convergence properties of the Kashin algorithm and its connection to the Kolmogorov width can lead to advancements in data quantization techniques, particularly in the context of large language models and transformer-based architectures.
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