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Inference without Interference: Disaggregate LLM Inference for Mixed Downstream Workloads

2024/01/20 by Cunchen Hu, Hu, Cunchen, Heyang Huang +21 · 31 citations
Computer Science · Engineering · #Cloud Computing and Resource Management #Distributed #FOS: Computer and information sciences #Ferroelectric and Negative Capacitance Devices #Parallel #Topic Modeling #and Cluster Computing (cs.DC)

paper · pdf · doi:10.48550/arxiv.2401.11181

openalex publication_date 2024/01/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Transformer-based large language model (LLM) inference serving is now the backbone of many cloud services. LLM inference consists of a prefill phase and a decode phase. However, existing LLM deployment practices often overlook the distinct characteristics of these phases, leading to significant interference. To mitigate interference, our insight is to carefully schedule and group inference requests based on their characteristics. We realize this idea in TetriInfer through three pillars. First, it partitions prompts into fixed-size chunks so that the accelerator always runs close to its computationsaturated limit. Second, it disaggregates prefill and decode instances so each can run independently. Finally, it uses a smart two-level scheduling algorithm augmented with predicted resource usage to avoid decode scheduling hotspots. Results show that TetriInfer improves time-to-first-token (TTFT), job completion time (JCT), and inference efficiency in turns of performance per dollar by a large margin, e.g., it uses 38% less resources all the while lowering average TTFT and average JCT by 97% and 47%, respectively.

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