Pre-requisites: Distributed shared memory

Distributed shared memory (DSM) is a key technology for achieving high performance in parallel computing. The main goal of DSM is to provide a shared memory abstraction that allows multiple processors to access a common memory space, even if the memory is physically distributed across multiple nodes in a cluster. This abstraction enables programs to run on a large-scale parallel system as if they were running on a single shared-memory machine, making it easier to develop, debug, and maintain parallel programs.

 

PLUS, or the Portable Library for Unified Shared Memory is a distributed shared memory (DSM) system developed by OpenAI. PLUS aims to provide a portable and scalable DSM solution that can be used to build high-performance parallel applications. Unlike traditional DSM systems, PLUS is designed to be easily portable across different computer architectures and operating systems, making it ideal for use in a wide range of environments.

PLUS also provides a number of other features that make it well-suited for use in high-performance computing. For example, PLUS provides a number of mechanisms for synchronizing access to shared memory, such as locks, semaphores, and barriers. These mechanisms allow multiple processors to coordinate their access to shared memory, ensuring that the data is consistent and that no race conditions occur.

PLUS also provides support for a number of different communication models, including both point-to-point and collective communication. This support makes it easier to develop parallel applications that can efficiently communicate with each other, even in the presence of slow or unreliable networks.

Advantages:

1. One of the main advantages of PLUS is its scalability. The system is designed to work well on both small-scale clusters and large-scale supercomputers, providing a single shared memory space that can be accessed by processors on multiple nodes. This shared memory space can be dynamically resized as needed, allowing for the efficient use of resources in a parallel environment.
2. Another advantage of PLUS is its support for dynamic load balancing. PLUS provides a number of mechanisms for dynamically balancing the load across processors, allowing for efficient use of resources and reducing the risk of load imbalance. This support makes PLUS well-suited for use in dynamic and changing environments, where the load on the system can change over time.

Finally, PLUS provides a number of performance optimizations that are designed to help improve the performance of parallel applications. These optimizations include support for data compression, caching, and prefetching, among others. These optimizations help to reduce the amount of data that needs to be transmitted across the network, reducing network traffic and improving overall performance.

In conclusion, PLUS is a highly scalable, portable, and efficient DSM system that provides a shared memory abstraction for high-performance parallel computing. With its support for dynamic load balancing, synchronization mechanisms, and performance optimizations, PLUS is an ideal solution for building high-performance parallel applications.