HedraRAG: Coordinating LLM Generation and Database Retrieval in Heterogeneous RAG Serving

Fuente: arXiv
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Auteurs principaux: Hu, Zhengding, Murthy, Vibha, Pan, Zaifeng, Li, Wanlu, Fang, Xiaoyi, Ding, Yufei, Wang, Yuke
Format: Preprint
Publié: 2025
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author Hu, Zhengding
Murthy, Vibha
Pan, Zaifeng
Li, Wanlu
Fang, Xiaoyi
Ding, Yufei
Wang, Yuke
author_facet Hu, Zhengding
Murthy, Vibha
Pan, Zaifeng
Li, Wanlu
Fang, Xiaoyi
Ding, Yufei
Wang, Yuke
contents This paper addresses emerging system-level challenges in heterogeneous retrieval-augmented generation (RAG) serving, where complex multi-stage workflows and diverse request patterns complicate efficient execution. We present HedraRAG, a runtime system built on a graph-based abstraction that exposes optimization opportunities across stage-level parallelism, intra-request similarity, and inter-request skewness. These opportunities are realized through dynamic graph transformations, such as node splitting, reordering, edge addition, and dependency rewiring, applied to wavefronts of subgraphs spanning concurrent requests. The resulting execution plans are mapped onto hybrid CPU-GPU pipelines to improve resource utilization and reduce latency. Evaluations across a wide range of RAG workflows demonstrate speedups exceeding 1.5x and reaching up to 5x over existing frameworks, showcasing the effectiveness of coordinated generation and retrieval in serving environments.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09138
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle HedraRAG: Coordinating LLM Generation and Database Retrieval in Heterogeneous RAG Serving
Hu, Zhengding
Murthy, Vibha
Pan, Zaifeng
Li, Wanlu
Fang, Xiaoyi
Ding, Yufei
Wang, Yuke
Databases
Machine Learning
This paper addresses emerging system-level challenges in heterogeneous retrieval-augmented generation (RAG) serving, where complex multi-stage workflows and diverse request patterns complicate efficient execution. We present HedraRAG, a runtime system built on a graph-based abstraction that exposes optimization opportunities across stage-level parallelism, intra-request similarity, and inter-request skewness. These opportunities are realized through dynamic graph transformations, such as node splitting, reordering, edge addition, and dependency rewiring, applied to wavefronts of subgraphs spanning concurrent requests. The resulting execution plans are mapped onto hybrid CPU-GPU pipelines to improve resource utilization and reduce latency. Evaluations across a wide range of RAG workflows demonstrate speedups exceeding 1.5x and reaching up to 5x over existing frameworks, showcasing the effectiveness of coordinated generation and retrieval in serving environments.
title HedraRAG: Coordinating LLM Generation and Database Retrieval in Heterogeneous RAG Serving
topic Databases
Machine Learning
url https://arxiv.org/abs/2507.09138