Algorithms for Implementing Relaxed Memory Consistency for Distributed Shared Memory

这个项目的目标是开发实现软件分布式共享存储器的算法，以减少处理器之间传输的消息数量和数据量。软件分布式共享内存(DSM)使进程即使在仅通过消息传递通信的处理器上执行时也能共享内存。近年来，紧耦合多处理器的开发人员采用了宽松的内存一致性模型来减少远程内存访问的延迟。然而，在分布式内存多处理器中，减少用于远程内存访问的消息数量同样重要。首席研究人员开发了一种算法，该算法实现了一种众所周知的称为释放一致性的松弛内存形式。这种称为延迟发布一致性的算法与大多数以前的工作不同，因为它是专门为软件DSM设计的，而不是模仿硬件实现。我们使用跟踪驱动的模拟的初步结果表明，延迟释放一致性显著地减少了消息数量和处理器之间传输的数据量。为了减少通信量，Lazy Release Consistency执行更多的计算。为了评估这种权衡的影响，在Munin DSM中实施了Lazy版本一致性，并将应用程序性能与以前的工作进行了比较。

The objective of this project is to develop algorithms for implementing a software distributed shared memory that reduce both the number of messages and the amount of data transferred between processors. A software distributed shared memory (DSM) enables processes to share memory even when they execute on processors that only communicate via message-passing. In recent years, the developers of tightly-coupled multiprocessors have adopted relaxed memory consistency models to reduce the latency of remote memory access. However, in a distributed memory multiprocessor, it is equally important to reduce the number of messages used for remote memory access. The principal investigator has developed an algorithm that implements a well known form of relaxed memory called Release Consistency. This algorithm, called Lazy Release Consistency, differs from most previous work because it is designed specifically for software DSM, rather then being an imitation of hardware implementations. Our preliminary results using trace-driven simulation indicate that Lazy Release Consistency significantly reduces both the number of messages and the amount of data transferred between processors. In order to reduce communication, Lazy Release Consistency performs more computation. To assess the impact of this trade-off, Lazy Release Consistency is being implemented in the Munin DSM and application program performance compared to previous work.