Fairness in Serving Large Language Models

Fuente: arXiv
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Autores principales: Sheng, Ying, Cao, Shiyi, Li, Dacheng, Zhu, Banghua, Li, Zhuohan, Zhuo, Danyang, Gonzalez, Joseph E., Stoica, Ion
Formato: Preprint
Publicado: 2023
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author Sheng, Ying
Cao, Shiyi
Li, Dacheng
Zhu, Banghua
Li, Zhuohan
Zhuo, Danyang
Gonzalez, Joseph E.
Stoica, Ion
author_facet Sheng, Ying
Cao, Shiyi
Li, Dacheng
Zhu, Banghua
Li, Zhuohan
Zhuo, Danyang
Gonzalez, Joseph E.
Stoica, Ion
contents High-demand LLM inference services (e.g., ChatGPT and BARD) support a wide range of requests from short chat conversations to long document reading. To ensure that all client requests are processed fairly, most major LLM inference services have request rate limits, to ensure that no client can dominate the request queue. However, this rudimentary notion of fairness also results in under-utilization of the resources and poor client experience when there is spare capacity. While there is a rich literature on fair scheduling, serving LLMs presents new challenges due to their unpredictable request lengths and their unique batching characteristics on parallel accelerators. This paper introduces the definition of LLM serving fairness based on a cost function that accounts for the number of input and output tokens processed. To achieve fairness in serving, we propose a novel scheduling algorithm, the Virtual Token Counter (VTC), a fair scheduler based on the continuous batching mechanism. We prove a 2x tight upper bound on the service difference between two backlogged clients, adhering to the requirement of work-conserving. Through extensive experiments, we demonstrate the superior performance of VTC in ensuring fairness, especially in contrast to other baseline methods, which exhibit shortcomings under various conditions. The reproducible code is available at https://github.com/Ying1123/VTC-artifact
format Preprint
id arxiv_https___arxiv_org_abs_2401_00588
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Fairness in Serving Large Language Models
Sheng, Ying
Cao, Shiyi
Li, Dacheng
Zhu, Banghua
Li, Zhuohan
Zhuo, Danyang
Gonzalez, Joseph E.
Stoica, Ion
Artificial Intelligence
Machine Learning
Performance
High-demand LLM inference services (e.g., ChatGPT and BARD) support a wide range of requests from short chat conversations to long document reading. To ensure that all client requests are processed fairly, most major LLM inference services have request rate limits, to ensure that no client can dominate the request queue. However, this rudimentary notion of fairness also results in under-utilization of the resources and poor client experience when there is spare capacity. While there is a rich literature on fair scheduling, serving LLMs presents new challenges due to their unpredictable request lengths and their unique batching characteristics on parallel accelerators. This paper introduces the definition of LLM serving fairness based on a cost function that accounts for the number of input and output tokens processed. To achieve fairness in serving, we propose a novel scheduling algorithm, the Virtual Token Counter (VTC), a fair scheduler based on the continuous batching mechanism. We prove a 2x tight upper bound on the service difference between two backlogged clients, adhering to the requirement of work-conserving. Through extensive experiments, we demonstrate the superior performance of VTC in ensuring fairness, especially in contrast to other baseline methods, which exhibit shortcomings under various conditions. The reproducible code is available at https://github.com/Ying1123/VTC-artifact
title Fairness in Serving Large Language Models
topic Artificial Intelligence
Machine Learning
Performance
url https://arxiv.org/abs/2401.00588