Cohesion: a hybrid memory model for accelerators

Two broad classes of memory models are available today: models with hardware cache coherence, used in conventional chip multiprocessors, and models that rely upon software to manage coherence, found in compute accelerators. In some systems, both types of models are supported using disjoint address spaces and/or physical memories. In this paper we present Cohesion, a hybrid memory model that enables fine-grained temporal reassignment of data between hardware-managed and software-managed coherence domains, allowing a system to support both. Cohesion can be used to dynamically adapt to the sharing needs of both applications and runtimes. Cohesion requires neither copy operations nor multiple address spaces. Cohesion offers the benefits of reduced message traffic and on-die directory overhead when software-managed coherence can be used and the advantages of hardware coherence for cases in which software-managed coherence is impractical. We demonstrate our protocol using a hierarchical,...

• Type: Conference
• Year: 2010
• Where: ISCA
• Authors: John H. Kelm, Daniel R. Johnson, William Tuohy, Steven S. Lumetta, Sanjay J. Patel
• Keywords: Address Space, Hardware, Hardware Coherence, ISCA 2010, Software-managed Coherence