CSPACER: A Reduced API Set Runtime for the Space Consistency Model
Khaled Z. Ibrahim · 2021
We present our design and implementation of a runtime for the Space Consistency model. The Space Consistency model is a generalized form of the full-empty bit synchronization for distributed memory programming, where a memory region is associated with a counter that determines its consistency and readiness for consumption. The model allows for efficient implementation of point-to-point data transfers and collective communication primitives as well. We present the interface design, implementation details, and performance results on Cray XC systems. Our runtime adopts a reduced API design to provide low-overhead initiation and processing of communication primitives, enable threaded execution of runtime functions, and provide efficient pipelining, thus improving the computation-communication overlap. We show the performance benefits of using this runtime both at the microbenchmark level and in application settings.