Physical scaling

• Integration at various levels
  • Chip-level integration to keep wires short: nCUBE/2 (1990) puts the processor, router, MMU, DRAM interface on a single chip
  • Board-level integration: Thinking machine CM-5 uses the core of a Sun SparcStation 1 and other peripherals on a single board to realize a node
  • System-level integration: IBM SP1 and SP2 exploit commodity RS6000 workstations and connect them through an external communication assist / network interface card and a router

IBM SP-2

Programming model

• Shared address space
  • Communication initiated by load/store instructions
  • Requires local or remote memory access before the data can be sent
  • Request/response protocol initiated by receiver
• Message passing
  • A one way communication: normally initiated by the sender
  • Number of sends can be buffered before a matching receive shows up
  • Synchronous vs. asynchronous sends
• Active messages
  • Restricted form of remote procedure call