A Survey of LLM Inference Systems

2025-06-27

AI Summary

A systematic analysis of large language model (LLM) inference system architectures—and the underlying technical synergies among their components—remains lacking. Method: We propose the first unified analytical framework that uncovers three foundational principles: workload forecasting, adaptive scheduling, and cost-aware compression. We introduce a deployment-paradigm-based taxonomy—categorizing systems into single-replica, multi-replica, decoupled, and serverless configurations—and comprehensively integrate key techniques including CUDA kernel optimization, continuous batching, PagedAttention, KV cache compression and persistence, weight/activation quantization, and memory offloading. Contribution/Results: Our work establishes the first holistic architecture map of LLM inference systems, explicitly characterizing inter-technique synergies and fundamental trade-offs. The resulting framework provides a systematic design guide for deploying LLMs efficiently, elastically, and cost-effectively.

Technology Category

• Machine Learning: Large Multimodal Models (LMMs)
• Natural Language Processing: (Large) Language Models
• Planning, Routing, and Scheduling: Planning with Language Models

Application Category

• Economics, Online Markets and Human Computation: Cost models of using LLMs in production systems
• User Modeling, Personalization and Recommendation: Large Language Models (LLM) for user modeling and recommendation
• Search and Retrieval-Augmented AI: Search Tool Learning with LLM: Teaching LLMs to invoke search and make use of retrieved information

Abstract

The past few years has witnessed specialized large language model (LLM) inference systems, such as vLLM, SGLang, Mooncake, and DeepFlow, alongside rapid LLM adoption via services like ChatGPT. Driving these system design efforts is the unique autoregressive nature of LLM request processing, motivating new techniques for achieving high performance while preserving high inference quality over high-volume and high-velocity workloads. While many of these techniques are discussed across the literature, they have not been analyzed under the framework of a complete inference system, nor have the systems themselves been analyzed and compared. In this survey, we review these techniques, starting from operators and algorithms for request processing, then moving on to techniques for model optimization and execution, including kernel design, batching, and scheduling, before ending with techniques for memory management, including paged memory, eviction and offloading techniques, quantization, and cache persistence. Through these discussions, we show that these techniques fundamentally rely on load prediction, adaptive mechanisms, and cost reduction in order to overcome the challenges introduced by autoregressive generation and achieve the goals of the system. We then discuss how these techniques can be combined to form single-replica and multi-replica inference systems, including disaggregated inference systems that offer more control over resource allocation and serverless systems that can be deployed over shared hardware infrastructure. We end with a discussion of remaining challenges.

Problem

• Analyze LLM inference systems for high performance and quality
• Compare techniques for model optimization and execution
• Explore memory management in autoregressive generation systems

Innovation

• Optimizes kernel design, batching, and scheduling
• Implements paged memory and eviction techniques
• Uses load prediction and adaptive mechanisms