Cache Coherence Protocols in Multiprocessor Systems: A Survey and Comparative Analysis

Abstract

Cache coherence is a fundamental requirement in shared memory multiprocessor systems where multiple processors access and modify shared data concurrently. With the increasing adoption of multicore architecture, efficient coherence mechanisms have become essential to ensure data consistency and high system performance. This paper presents a survey and comparative analysis of widely used cache coherence protocols in multiprocessor systems. The study reviews the fundamental concepts of cache coherence and categorizes coherence mechanisms based on their architectural approaches. Classical protocols including MSI, MESI, MOESI, and MESIF are examined with respect to their state models, operational mechanisms, and performance characteristics. A comparative analysis is presented to highlight the differences among these protocols in terms of scalability, communication overhead, and implementation complexity. In addition, the paper discusses key design challenges such as coherence traffic, latency, and energy consumption, and reviews emerging research directions including adaptive coherence techniques, machine-learning-assisted optimization, and coherence support for heterogeneous computing systems. The insights provided in this survey help researchers and system designers understand the strengths and limitations of existing coherence mechanisms and support the development of scalable and efficient coherence solutions for future multiprocessor architectures.