🚀 go-pugleaf

In article <31963@ucbvax.BERKELEY.EDU> verma@ucbarpa.Berkeley.EDU.UUCP (Dinesh C. Verma) writes:
>I am interested in knowing the impact of fast networks on the 
>architecture and organisation of (futuristic?) computer systems.
>......
>	Uptil now networks and computer architecture have evolved
>independently. Part of the reason has been the separation between
>the I/O architecture and the CPU/MEMORY system. However, since 
>networks are so common nowdays, it is hard to believe that they 
>need not have any impact on the architecture of a machine.

You might like to check out the ICL (U.K.) operating system VME and the hardware
that goes with it. The I/O and CPU/MEMORY are totally seperate but the system is
linked together *internally* by high speed (250Mbit/sec), local area networks.
I do not mean a bus system, this is an intelegent level 4 transport service.

In the latest version of the VME Architecture the Disc, intra central suite and
'slow' device systems are all based on LANs. The 'slow' devices run on Ethernet
LAN's running at 10 Mbit/sec. 

The overall system performance is VERY good, the use of networking techniques
inside the "CPU" doesn't slow things down and makes totally resilient systems
available on a general purpose commercial mainframe. There are no restrictions
or special techniques for the software.

In most multi systems where the processors are a shared resource to a single
operating system there are severe multi-processor overheads because of the 
problems involved in shared access to i/o controllers and store. Most systems
get no better than 1.3 times a single for two processors unless these are
segregated and so become two operating systems sharing certain resource. In VME
this is not a problem, factors of 1.8 are common. This factor doesn't change
much for more processors, i.e. at 4 one can get 3.2 to 3.6 with no problems.

Its worth looking out for.