topology  - Program to display Altix 3000 machine configu­
       ration


SYNOPSIS

       topology


DESCRIPTION

       topology is a Bourne shell script that uses information in
       /dev/hw  to  print  a  description of an Altix 3000 system
       configuration.  This command is useful to make  sure  that
       the user's view of the system hardware matches that of the
       firmware and operating system.  For example, the user  may
       expect  processor  0  and  1  to be processors on the same
       front-side bus in a particular node.  However, under  cer­
       tain conditions, the system configuration can be different
       from what is expected.  Applications whose performance  is
       sensitive  to  process  placement may run more slowly than
       expected in this case, and the user may need to  know  the
       current  system  configuration in order to assist in diag­
       nosing this problem.

       The command can also be used  to  determine  the  relative
       "closeness"  of  various  processors  and  memory  to  one
       another (since this depends on the number of links that  a
       request needs to traverse in order to get from one proces­
       sor to another.)

       Finally, this command is useful to print the  system  con­
       figuration  either before or after a change in system par­
       titioning to make sure tha the system was  partitioned  as
       intended.


EXAMPLE

       The  following  is  the output generated by topology on an
       internal machine at SGI:

       <-----------------------sample output begins

       Machine tester.sgi.com has: 6 cpu's 3 memory nodes

        The cpus are:
        cpu 0 is /dev/hw/module/001c11/slab/0/node/cpubus/0/a
        cpu 1 is /dev/hw/module/001c11/slab/0/node/cpubus/0/c
        cpu 2 is /dev/hw/module/001c11/slab/1/node/cpubus/0/a
        cpu 3 is /dev/hw/module/001c11/slab/1/node/cpubus/0/c
        cpu 4 is /dev/hw/module/001c14/slab/1/node/cpubus/0/a
        cpu 5 is /dev/hw/module/001c14/slab/1/node/cpubus/0/c

        The nodes are:
        node 0 is /dev/hw/module/001c11/slab/0/node
        node 1 is /dev/hw/module/001c11/slab/1/node
        node 2 is /dev/hw/module/001c14/slab/1/node

        /dev/hw/module/001c11/slab/0/node/link/1 is  /dev/hw/mod­
       ule/001c11/slab/1/node
        /dev/hw/module/001c11/slab/1/node/link/1  is /dev/hw/mod­
       ule/001c11/slab/0/node
        /dev/hw/module/001c11/slab/1/node/link/2 is  /dev/hw/mod­
       ule/001c14/slab/1/node
        /dev/hw/module/001c14/slab/1/node/link/2  is /dev/hw/mod­
       ule/001c11/slab/1/node

        /dev/hw/module/001c11/slab/0/node/xtalk/0/link         ->
       /dev/hw/module/001c11/slab/0/Pbrick

       <---------------------sample output ends

       This output indicates that:

       ˇ    The system has 6 cpu's and 3 nodes.

       ˇ    Cpu's  0  and 1 are on the node with internal identi­
            fier 001c11/slab/0.

       ˇ    Cpu's 2 and 3 are on the node with  internal  identi­
            fier 001c11/slab/0.

       ˇ    Cpu's  4  and 5 are on the node with internal identi­
            fier 001c14/slab/1.

       ˇ    Cpu's 0 and 1 are processors on the same  front  side
            bus  in node 001c11/slab/0.  (They are cpubus/0/a and
            cpubus/0/c on that node).

       ˇ    Cpu's 2 and 3 are processors on the  same  front-side
            bus in node 001c11/slab/1.

       ˇ    Cpu's  3  and 4 are processors on the same front-side
            bus in node 001c11/slab/1.

       ˇ    Numalink  connections  run  from   001c11/slab/0   to
            001c11/slab/1 and back.

       ˇ    Numalink   connections   run  from  001c11/slab/1  to
            001c14/slab/1  and  back.   Thus,   memory   requests
            orginating  on node 001c14/slab/1 that are drected to
            memory located on node 001c11/slab/0  get  there  via
            node 001c11/slab/1.

       ˇ    The  processors  at  001c14/slab/0  are not currently
            part of  the  configuration.   (They  may  either  be
            absent or offline for some reason.)

       ˇ    node 001c11's xtalk link A is connected to a Pbrick


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