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Main Authors: Pulishetty, Roshini, Ghantasala, Mani Kishan, Dasoju, Keerthy Kaushik, Mangwani, Niti, Garimella, Vishal, Mate, Aditya, Chatterjee, Somya, Kang, Yue, Nosakhare, Ehi, Hasan, Sadid, Srinivasan, Soundar
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.09782
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author Pulishetty, Roshini
Ghantasala, Mani Kishan
Dasoju, Keerthy Kaushik
Mangwani, Niti
Garimella, Vishal
Mate, Aditya
Chatterjee, Somya
Kang, Yue
Nosakhare, Ehi
Hasan, Sadid
Srinivasan, Soundar
author_facet Pulishetty, Roshini
Ghantasala, Mani Kishan
Dasoju, Keerthy Kaushik
Mangwani, Niti
Garimella, Vishal
Mate, Aditya
Chatterjee, Somya
Kang, Yue
Nosakhare, Ehi
Hasan, Sadid
Srinivasan, Soundar
contents The proliferation of large language models (LLMs) with varying computational costs and performance profiles presents a critical challenge for scalable, cost-effective deployment in real-world applications. We introduce a unified routing framework that leverages a single-head cross-attention mechanism to jointly model query and model embeddings, enabling dynamic selection of the optimal LLM for each input query. Our approach is evaluated on RouterBench, a large-scale, publicly available benchmark encompassing diverse LLM pools and domains. By explicitly capturing fine-grained query-model interactions, our router predicts both response quality and generation cost, achieving up to 6.6% improvement in Average Improvement in Quality (AIQ) and 2.9% in maximum performance over existing routers. To robustly balance performance and cost, we propose an exponential reward function that enhances stability across user preferences. The resulting architecture is lightweight, generalizes effectively across domains, and demonstrates improved efficiency compared to prior methods, establishing a new standard for cost-aware LLM routing.
format Preprint
id arxiv_https___arxiv_org_abs_2509_09782
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle One Head, Many Models: Cross-Attention Routing for Cost-Aware LLM Selection
Pulishetty, Roshini
Ghantasala, Mani Kishan
Dasoju, Keerthy Kaushik
Mangwani, Niti
Garimella, Vishal
Mate, Aditya
Chatterjee, Somya
Kang, Yue
Nosakhare, Ehi
Hasan, Sadid
Srinivasan, Soundar
Machine Learning
The proliferation of large language models (LLMs) with varying computational costs and performance profiles presents a critical challenge for scalable, cost-effective deployment in real-world applications. We introduce a unified routing framework that leverages a single-head cross-attention mechanism to jointly model query and model embeddings, enabling dynamic selection of the optimal LLM for each input query. Our approach is evaluated on RouterBench, a large-scale, publicly available benchmark encompassing diverse LLM pools and domains. By explicitly capturing fine-grained query-model interactions, our router predicts both response quality and generation cost, achieving up to 6.6% improvement in Average Improvement in Quality (AIQ) and 2.9% in maximum performance over existing routers. To robustly balance performance and cost, we propose an exponential reward function that enhances stability across user preferences. The resulting architecture is lightweight, generalizes effectively across domains, and demonstrates improved efficiency compared to prior methods, establishing a new standard for cost-aware LLM routing.
title One Head, Many Models: Cross-Attention Routing for Cost-Aware LLM Selection
topic Machine Learning
url https://arxiv.org/abs/2509.09782