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arXiv 2403.01136cs.LGcs.AIcs.DC
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LLM-PQ:利用阶段感知划分与自适应量化在异构集群上服务 LLM

LLM-PQ: Serving LLM on Heterogeneous Clusters with Phase-Aware Partition and Adaptive Quantization

University of Hong Kong(香港大学);ByteDance Inc.(字节跳动公司)

Juntao Zhao, Borui Wan, Yanghua Peng, Haibin Lin, Chuan Wu

AI总结:

针对异构 GPU 集群上 LLM 服务成本高、现有方案仅适合同构设备的问题,本文提出 LLM-PQ,通过自适应混合精度量化、阶段感知划分和微批次设置,在满足质量目标下最高提升推理吞吐量 2.88 倍。

摘要:

大规模语言模型(LLM)近期的突破已在各类任务上展现出令人瞩目的性能。LLM 的巨大规模导致运行这些模型需要极高的资源需求和成本。尽管如今模型大多使用统一的高性能 GPU 提供服务,但利用由可用的高容量和低容量 GPU 混合组成的异构集群,有可能大幅降低服务成本。目前缺乏支持使用异构集群高效进行 LLM 服务的设计,而现有解决方案聚焦于同构设备之间的模型划分和统一压缩。本文提出 LLM-PQ,这是一个倡导自适应模型量化和阶段感知划分的系统,用于提升异构 GPU 集群上的 LLM 服务效率。我们通过一种高效算法,在分布式 LLM 服务中审慎地共同决定混合精度模型量化、阶段感知模型划分以及微批次大小,从而在满足用户指定模型质量目标的同时大幅提高推理吞吐量。在 11 个不同集群上针对生产推理工作负载进行的大量实验表明,LLM-PQ 实现了最高 2.88 倍(平均 2.26 倍)的推理吞吐量提升,展现出相较于最先进工作的显著优势。

英文摘要:

Recent breakthroughs in Large-scale language models (LLMs) have demonstrated impressive performance on various tasks. The immense sizes of LLMs have led to very high resource demand and cost for running the models. Though the models are largely served using uniform high-caliber GPUs nowadays, utilizing a heterogeneous cluster with a mix of available high- and low-capacity GPUs can potentially substantially reduce the serving cost. There is a lack of designs to support efficient LLM serving using a heterogeneous cluster, while the current solutions focus on model partition and uniform compression among homogeneous devices. This paper proposes LLM-PQ, a system that advocates adaptive model quantization and phase-aware partition to improve LLM serving efficiency on heterogeneous GPU clusters. We carefully decide on mixed-precision model quantization together with phase-aware model partition and micro-batch sizing in distributed LLM serving with an efficient algorithm, to greatly enhance inference throughput while fulfilling user-specified model quality targets. Extensive experiments on production inference workloads in 11 different clusters demonstrate that LLM-PQ achieves up to 2.88x (2.26x on average) throughput improvement in inference, showing great advantages over state-of-the-art works.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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