Rhymes+: A Software Shared Virtual Memory System with Three Way Coherence Protocols on the Intel Single-Chip Cloud Computer

摘要

This research focuses on one prominent many-core prototype-the Intel's Single-chip Cloud Computer (SCC). We address the performance problem of shared virtual memory consistency for this cache in-coherent architecture. Aiming to keep data on-chip as much as possible to reduce memory accesses external to the chip, we propose two techniques to leverage the cache hierarchy to its full and make data reside in the on-chip scratchpad memory. First, targeted at the architectural specificity of the hardware, we redesigned the traditional software distributed shared memory (SDSM) to allow shared data to be treated transparently like private memory so that the cache hierarchy can be fully utilised without sacrificing memory consistency. Second, we propose a distance-aware page allocation scheme that samples access frequencies and selects the most frequently-recently used pages to be stored on the on-chip scratchpad memory.