SPLIT: SymPathy for Large jobs Improves Tail latency

Fuente: arXiv
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Main Authors: Li, Zhouzi, Harchol-Balter, Mor, Scheller-Wolf, Alan
Format: Preprint
Published: 2026
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author Li, Zhouzi
Harchol-Balter, Mor
Scheller-Wolf, Alan
author_facet Li, Zhouzi
Harchol-Balter, Mor
Scheller-Wolf, Alan
contents We study the asymptotic response time tail in the M/G/n multi-server queue with heavy-tailed (regularly varying) job sizes, a setting representative of modern computing workloads. For single-server systems, tail optimization is well understood: under heavy-tailed job sizes, policies such as SRPT that strictly prioritize short jobs are strongly tail optimal, and giving any priority to large jobs is harmful. For multi-server systems, the question has been almost entirely open. This paper gives the first strongly tail-optimal scheduling policies for the M/G/n queue with heavy-tailed job sizes. Our central finding is that the multi-server case is intrinsically different from the single-server case: giving a small amount of ``sympathy'' to large jobs is essential for strong tail optimality. We establish strong (or arbitrarily close to strong) tail optimality across the full stability region, both with and without knowledge of job sizes.
format Preprint
id arxiv_https___arxiv_org_abs_2605_13749
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle SPLIT: SymPathy for Large jobs Improves Tail latency
Li, Zhouzi
Harchol-Balter, Mor
Scheller-Wolf, Alan
Performance
Probability
We study the asymptotic response time tail in the M/G/n multi-server queue with heavy-tailed (regularly varying) job sizes, a setting representative of modern computing workloads. For single-server systems, tail optimization is well understood: under heavy-tailed job sizes, policies such as SRPT that strictly prioritize short jobs are strongly tail optimal, and giving any priority to large jobs is harmful. For multi-server systems, the question has been almost entirely open. This paper gives the first strongly tail-optimal scheduling policies for the M/G/n queue with heavy-tailed job sizes. Our central finding is that the multi-server case is intrinsically different from the single-server case: giving a small amount of ``sympathy'' to large jobs is essential for strong tail optimality. We establish strong (or arbitrarily close to strong) tail optimality across the full stability region, both with and without knowledge of job sizes.
title SPLIT: SymPathy for Large jobs Improves Tail latency
topic Performance
Probability
url https://arxiv.org/abs/2605.13749