ConfigSpec: Profiling-Based Configuration Selection for Distributed Edge--Cloud Speculative LLM Serving

Fuente: arXiv
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Autores principales: Li, Xiangchen, Ghafouri, Saeid, Fan, Jiakun, Ali, Babar, Vandierendonck, Hans, Nikolopoulos, Dimitrios S.
Formato: Preprint
Publicado: 2026
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author Li, Xiangchen
Ghafouri, Saeid
Fan, Jiakun
Ali, Babar
Vandierendonck, Hans
Nikolopoulos, Dimitrios S.
author_facet Li, Xiangchen
Ghafouri, Saeid
Fan, Jiakun
Ali, Babar
Vandierendonck, Hans
Nikolopoulos, Dimitrios S.
contents Speculative decoding enables collaborative Large Language Model (LLM) inference across cloud and edge by separating lightweight token drafting from heavyweight verification. While prior systems show performance and cost benefits, practical deployment requires navigating a large configuration space spanning draft model variants, quantisation levels, speculative lengths, and heterogeneous edge devices. This paper presents ConfigSpec, a configurationselection framework for distributed speculative LLM serving. ConfigSpec profiles edge devices and draft-target alignment, and models drafting throughput, acceptance rate, and power to evaluate goodput, verification cost efficiency, and energy efficiency across the joint configuration space. Our analysis across three edge platforms and two LLM families reveals structurally conflicting optima. Firstly, goodput is maximised by the smallest, fastest draft model at device-dependent speculative lengths (K*=2-10). Secondly, both cost and energy efficiency converge to K=2 due to a dominant bonus-token effect-with cost favouring the largest drafter for its high acceptance rate and energy favouring the smallest for its low power draw. These conflicts confirm that no single fixed configuration can simultaneously optimise all objectives, underscoring the need for profiling-based configuration selection in disaggregated edge-cloud LLM inference.
format Preprint
id arxiv_https___arxiv_org_abs_2604_09722
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle ConfigSpec: Profiling-Based Configuration Selection for Distributed Edge--Cloud Speculative LLM Serving
Li, Xiangchen
Ghafouri, Saeid
Fan, Jiakun
Ali, Babar
Vandierendonck, Hans
Nikolopoulos, Dimitrios S.
Distributed, Parallel, and Cluster Computing
Artificial Intelligence
C.2.4; D.4.8; D.4.1; F.2.2; I.2.7; D.4.7
Speculative decoding enables collaborative Large Language Model (LLM) inference across cloud and edge by separating lightweight token drafting from heavyweight verification. While prior systems show performance and cost benefits, practical deployment requires navigating a large configuration space spanning draft model variants, quantisation levels, speculative lengths, and heterogeneous edge devices. This paper presents ConfigSpec, a configurationselection framework for distributed speculative LLM serving. ConfigSpec profiles edge devices and draft-target alignment, and models drafting throughput, acceptance rate, and power to evaluate goodput, verification cost efficiency, and energy efficiency across the joint configuration space. Our analysis across three edge platforms and two LLM families reveals structurally conflicting optima. Firstly, goodput is maximised by the smallest, fastest draft model at device-dependent speculative lengths (K*=2-10). Secondly, both cost and energy efficiency converge to K=2 due to a dominant bonus-token effect-with cost favouring the largest drafter for its high acceptance rate and energy favouring the smallest for its low power draw. These conflicts confirm that no single fixed configuration can simultaneously optimise all objectives, underscoring the need for profiling-based configuration selection in disaggregated edge-cloud LLM inference.
title ConfigSpec: Profiling-Based Configuration Selection for Distributed Edge--Cloud Speculative LLM Serving
topic Distributed, Parallel, and Cluster Computing
Artificial Intelligence
C.2.4; D.4.8; D.4.1; F.2.2; I.2.7; D.4.7
url https://arxiv.org/abs/2604.09722