Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!aglew From: aglew@oberon.csg.uiuc.edu (Andy Glew) Newsgroups: comp.arch Subject: Re: Bus Partitioning? Message-ID: Date: 12 Feb 90 22:11:41 GMT References: <1990Jan30.174807.14657@ncsuvx.ncsu.edu> <6960003@hp-and.HP.COM> <647@m1.cs.man.ac.uk> Sender: news@ux1.cso.uiuc.edu (News) Organization: University of Illinois, Computer Systems Group Lines: 35 In-Reply-To: mshute@r4.uucp's message of 8 Feb 90 12:21:43 GMT >And in article aglew@dwarfs.csg.uiuc.edu (Andy Glew) writes: > >>One of the busses may be designated the "global" bus, listened to by all >>processors. >> Others might be allocated to connect groups of processors (and I/O >>controllers) as needed. This reconfiguration would be done infrequently. >> So, for example, if you have an I/O going on, allocate it a bus >>for the (long) duration of the I/O. >> Or, if a group of programs appear to communicate heavily, allocate >>them a private bus. > >This sounds like an implementation of a tree network. > >Malcolm Shute. (The AM Mollusc: v_@_ ) Disclaimer: all Tree is a fixed topology. I mean a system where any components can talk directly on a private link - just requiring a bit of setup. Hmmm... this sounds a lot like a fiber-optic WAN that somebody from IBM just presented. Bandwidth limited by the speed of electronics attached to the net. Since aggregate bandwidth of optics >> bandwidth of receiving electronics, you can have almost unlimited simultaneous conversations. Except that a receiver can only listen to one frequency band at a time. Senders can only send one frequency at a time. Senders can only send on a fixed frequency (tuneable lasers expensive/impractical). Receivers can only change frequency they are listening to infrequently (tuneable receivers slow (currently physical (piezoelectric) eventually electroacoustic). Modulo switching protocol difficulties, here's your complete crossbar. What type of system are we going to put on this interconnect? -- Andy Glew, aglew@uiuc.edu