The Stanford FLASH multiprocessor

The FLASH multiprocessor efficiently integrates support for cache-coherent shared memory and high-performance message passing, while minimizing both hardware and software overhead. Each node in FLASH contains a microprocessor, a portion of the machine's global memory, a port to the interconnection network, an I/O interface, and a custom node controller called MAGIC. The MAGIC chip handles all communication both within the node and among nodes, using hardwired data paths for efficient data movement and a programmable processor optimized for executing protocol operations. The use of the protocol processor makes FLASH very flexible --- it can support a variety of different communication mechanisms --- and simplifies the design and implementation.This paper presents the architecture of FLASH and MAGIC, and discusses the base cache-coherence and message-passing protocols. Latency and occupancy numbers, which are derived from our system-level simulator and our Verilog code, are given for several common protocol operations. The paper also describes our software strategy and FLASH's current status.