Piton: A Manycore Processor for Multitenant Clouds.

The shared cloud-based computing paradigm has experienced enormous growth. Multitenant clouds are conventionally built atop datacenters that utilize commodity hardware connected hierarchically with standard network protocols. Piton is a 25-core manycore processor that takes a different perspective, rethinking the architecture of datacenters and specializing processor architecture for Infrastructure as a Service (IaaS) clouds. The tile-based manycore processor is designed not only as a single chip, but as a large-scale system. Up to 8,192 chips (204,800 cores) can be seamlessly connected in a flat topology, maintaining a packet-switched network fabric both on and off chip. Shared memory is supported across arbitrary cores in the system, both intrachip and interchip, enabling flexibility and fine-grained resource allocation in shared systems. Piton also targets energy efficiency, critical to datacenters, using a modified multithreaded OpenSPARC T1 core enhanced with an energy-efficient drafting mode. To further facilitate sharing and increase utility for IaaS users and providers, a novel memory traffic shaper partitions bandwidth among cores or applications. Piton reimagines the datacenter architecture, breaking down barriers between chips, nodes, and racks, and enables flexibility, performance, and energy efficiency at scale. Piton has also been open sourced as a research platform called OpenPiton to enable practical full-system manycore research.