The paper "Memory Coherence in Shared Virtual Memory Systems" by KAI LI and PAUL HUDAK explores the challenges and solutions for implementing shared virtual memory on loosely coupled multiprocessors. The authors present two classes of algorithms—centralized and distributed—to address the memory coherence problem, which is crucial for efficient data access and process migration in such systems. A prototype system called IVY has been developed and tested on an Apollo ring, demonstrating the feasibility of shared virtual memory in a loosely coupled multiprocessor environment. The shared virtual memory allows application programs to use a single virtual address space across multiple processors, enabling efficient data migration and process migration. The main challenge is maintaining memory coherence, ensuring that read and write operations return consistent values. The paper discusses various strategies for maintaining coherence, including page synchronization (invalidation and write-broadcast) and page ownership (fixed and dynamic). Two types of algorithms are considered: centralized and distributed. Centralized algorithms use a single manager to coordinate page ownership and synchronization, while distributed algorithms distribute this responsibility among individual processors. The authors propose and analyze several distributed algorithms, including a fixed distributed manager, a broadcast distributed manager, and a dynamic distributed manager. The dynamic distributed manager is shown to be particularly effective, with a worst-case number of messages for locating a page owner being \(O(N + K \log N)\). The paper also discusses the implementation details of these algorithms, including data structures and communication protocols, and provides experimental results to validate their performance. The results show that the dynamic distributed manager algorithm performs well, even in large-scale multiprocessor systems, making it a viable solution for shared virtual memory in loosely coupled multiprocessors.The paper "Memory Coherence in Shared Virtual Memory Systems" by KAI LI and PAUL HUDAK explores the challenges and solutions for implementing shared virtual memory on loosely coupled multiprocessors. The authors present two classes of algorithms—centralized and distributed—to address the memory coherence problem, which is crucial for efficient data access and process migration in such systems. A prototype system called IVY has been developed and tested on an Apollo ring, demonstrating the feasibility of shared virtual memory in a loosely coupled multiprocessor environment. The shared virtual memory allows application programs to use a single virtual address space across multiple processors, enabling efficient data migration and process migration. The main challenge is maintaining memory coherence, ensuring that read and write operations return consistent values. The paper discusses various strategies for maintaining coherence, including page synchronization (invalidation and write-broadcast) and page ownership (fixed and dynamic). Two types of algorithms are considered: centralized and distributed. Centralized algorithms use a single manager to coordinate page ownership and synchronization, while distributed algorithms distribute this responsibility among individual processors. The authors propose and analyze several distributed algorithms, including a fixed distributed manager, a broadcast distributed manager, and a dynamic distributed manager. The dynamic distributed manager is shown to be particularly effective, with a worst-case number of messages for locating a page owner being \(O(N + K \log N)\). The paper also discusses the implementation details of these algorithms, including data structures and communication protocols, and provides experimental results to validate their performance. The results show that the dynamic distributed manager algorithm performs well, even in large-scale multiprocessor systems, making it a viable solution for shared virtual memory in loosely coupled multiprocessors.