Discussed environment

Discussed environment

Information transmission is a critical part in multiprocessor arrangments as is the choice of tecnology at each procesor node. In this document we discuss higly symmetric multiprocessor systems distinguished by the following caracteristics:

• each processor provides just minimal processing and I/O functions - we use preferably an array of tiny CPU-cores on one silicon chip or PCB-board
• each processor counts with a small amount of RAM and ROM, eventually with very high speed access.
• each node can be constructed by one processor, or in turn by another array of several cores.
• the nodes are directly interconnected with high speed data links/busses. The used interconnection topology does not play the principal role in the discussion.
• The array has medium to high speed access to similar amounts of conventional RAM found in todays workstations
• Input/Output functions of the array are taken over by the edge nodes, either via direct comunication with onboard I/O controllers or with specialized procesors which interact with the array via it's interconection busses.

height=2in]tide/array.fig

This environment is inspired by the availability of very small, high performance, low cost CPU-cores, which are easy to multiply on one chip.

Standard symmetric multiprocessor aproaches, require complex hardware to manage shared access of several CPU's to shared RAM, which converts main memory in a bottleneck and raises higly complicate sincronization issues partially dealed with in the hardware.

On the other hand, in distributed systems, serveral independent high performance computers are connected together via a high speed LAN, each of them running their own operating system. In either case, the CPU's involved use wide address busses and again highly complex hardware acceleration mecanisms: floating point units, n-level memory caching, memory segmentation and paging, etc. resulting in high per unit costs in both hard- and software.

We hope that this new approach, which combines very larg amounts of "dumb" CPU's in combination with new programming approaches, can compete in price, security and performance with the standard solutions actually deployed.

Discussed environment