Efficiency-Effectiveness Reranking FLOPs for LLM-based Rerankers

Fuente: arXiv
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Main Authors: Peng, Zhiyuan, Wei, Ting-ruen, Song, Tingyu, Zhao, Yilun
Format: Preprint
Published: 2025
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author Peng, Zhiyuan
Wei, Ting-ruen
Song, Tingyu
Zhao, Yilun
author_facet Peng, Zhiyuan
Wei, Ting-ruen
Song, Tingyu
Zhao, Yilun
contents Large Language Models (LLMs) have recently been applied to reranking tasks in information retrieval, achieving strong performance. However, their high computational demands often hinder practical deployment. Existing studies evaluate the efficiency of LLM-based rerankers using proxy metrics such as latency, the number of forward passes, input tokens, and output tokens. However, these metrics depend on hardware and running-time choices (\eg parallel or not, batch size, etc), and often fail to account for model size, making it difficult to interpret and obscuring the evaluation of the efficiency-effectiveness tradeoff. To address this issue, we propose \ours\footnote{https://github.com/zhiyuanpeng/EER-FLOPs.} for LLM-based rerankers: RPP (ranking metrics per PetaFLOP), measuring how much ranking quality (e.g., NDCG or MRR) a method achieves per PetaFLOP, and QPP (queries per PetaFLOP), measuring how many queries can be processed per PetaFLOP. Accompanied by the new metrics, an interpretable FLOPs estimator is developed to estimate the FLOPs of an LLM-based reranker even without running any experiments. Based on the proposed metrics, we conduct comprehensive experiments to evaluate a wide range of LLM-based rerankers with different architectures, studying the efficiency-effectiveness trade-off and bringing this issue to the attention of the research community.
format Preprint
id arxiv_https___arxiv_org_abs_2507_06223
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Efficiency-Effectiveness Reranking FLOPs for LLM-based Rerankers
Peng, Zhiyuan
Wei, Ting-ruen
Song, Tingyu
Zhao, Yilun
Computation and Language
Artificial Intelligence
Machine Learning
Large Language Models (LLMs) have recently been applied to reranking tasks in information retrieval, achieving strong performance. However, their high computational demands often hinder practical deployment. Existing studies evaluate the efficiency of LLM-based rerankers using proxy metrics such as latency, the number of forward passes, input tokens, and output tokens. However, these metrics depend on hardware and running-time choices (\eg parallel or not, batch size, etc), and often fail to account for model size, making it difficult to interpret and obscuring the evaluation of the efficiency-effectiveness tradeoff. To address this issue, we propose \ours\footnote{https://github.com/zhiyuanpeng/EER-FLOPs.} for LLM-based rerankers: RPP (ranking metrics per PetaFLOP), measuring how much ranking quality (e.g., NDCG or MRR) a method achieves per PetaFLOP, and QPP (queries per PetaFLOP), measuring how many queries can be processed per PetaFLOP. Accompanied by the new metrics, an interpretable FLOPs estimator is developed to estimate the FLOPs of an LLM-based reranker even without running any experiments. Based on the proposed metrics, we conduct comprehensive experiments to evaluate a wide range of LLM-based rerankers with different architectures, studying the efficiency-effectiveness trade-off and bringing this issue to the attention of the research community.
title Efficiency-Effectiveness Reranking FLOPs for LLM-based Rerankers
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2507.06223