Exploring Fine-Tuning for In-Context Retrieval and Efficient KV-Caching in Long-Context Language Models

Fuente: arXiv
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Main Authors: Molfese, Francesco Maria, Hardalov, Momchil, Blloshmi, Rexhina, Byrne, Bill, de Gispert, Adrià
Format: Preprint
Published: 2026
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author Molfese, Francesco Maria
Hardalov, Momchil
Blloshmi, Rexhina
Byrne, Bill
de Gispert, Adrià
author_facet Molfese, Francesco Maria
Hardalov, Momchil
Blloshmi, Rexhina
Byrne, Bill
de Gispert, Adrià
contents With context windows of millions of tokens, Long-Context Language Models (LCLMs) can encode entire document collections, offering a strong alternative to conventional retrieval-augmented generation (RAG). However, it remains unclear whether fine-tuning strategies can improve long-context performance and translate to greater robustness under KV-cache compression techniques. In this work, we investigate which training strategies most effectively enhance LCLMs' ability to identify and use relevant information, as well as enhancing their robustness under KV-cache compression. Our experiments show substantial in-domain improvements, achieving gains of up to +20 points over the base model. However, out-of-domain generalization remains task dependent with large variance -- LCLMs excels on finance questions (+9 points), while RAG shows stronger performance on multiple-choice questions (+6 points) over the baseline models. Finally, we show that our fine-tuning approaches bring moderate improvements in robustness under KV-cache compression, with gains varying across tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2601_18527
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Exploring Fine-Tuning for In-Context Retrieval and Efficient KV-Caching in Long-Context Language Models
Molfese, Francesco Maria
Hardalov, Momchil
Blloshmi, Rexhina
Byrne, Bill
de Gispert, Adrià
Computation and Language
With context windows of millions of tokens, Long-Context Language Models (LCLMs) can encode entire document collections, offering a strong alternative to conventional retrieval-augmented generation (RAG). However, it remains unclear whether fine-tuning strategies can improve long-context performance and translate to greater robustness under KV-cache compression techniques. In this work, we investigate which training strategies most effectively enhance LCLMs' ability to identify and use relevant information, as well as enhancing their robustness under KV-cache compression. Our experiments show substantial in-domain improvements, achieving gains of up to +20 points over the base model. However, out-of-domain generalization remains task dependent with large variance -- LCLMs excels on finance questions (+9 points), while RAG shows stronger performance on multiple-choice questions (+6 points) over the baseline models. Finally, we show that our fine-tuning approaches bring moderate improvements in robustness under KV-cache compression, with gains varying across tasks.
title Exploring Fine-Tuning for In-Context Retrieval and Efficient KV-Caching in Long-Context Language Models
topic Computation and Language
url https://arxiv.org/abs/2601.18527