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numa(5)

 NAME

     numa - non uniform memory access

 DESCRIPTION

     This document briefly describes the IRIX NUMA memory management
     subsystem, and provides a top level index for all NUMA management tools
     available in Origin systems.

   Topology
     The command topology(1) can be used to get a quick view of the topology
     of an Origin system. This command produces output that lists processors,
     nodes, routers, and the links that connect all these devices. For more
     information, see hinv(1) and hwgraph(4).

   Name Spaces for Nodes
     There are several related name spaces for nodes. The main name space is
     that provided by the hardware graph, where a name is a string of
     characters in the form of a path that both identifies a node and defines
     its location relative to the overall hardware.

          $ find /hw -name node -print
          /hw/module/1/slot/n1/node
          /hw/module/1/slot/n2/node
          /hw/module/1/slot/n3/node
          /hw/module/1/slot/n4/node
          /hw/module/2/slot/n1/node
          /hw/module/2/slot/n2/node
          /hw/module/2/slot/n3/node
          /hw/module/2/slot/n4/node

     Another highly visible name space for nodes is the Compact Node
     Identifiers. This space is just a compact enumeration of the nodes
     currently available in the system, from 0 to NUMNODES-1.  These numbers
     are known as cnodeids and their relation to path names is defined by the
     hardware graph directory /hw/nodenum.

          $ cd /hw/nodenum
          $ ls -l
          total 0
          lrw-------    1 root     sys           26 Jul 10 13:36 0 -> /hw/module/1/slot/n1/node
          lrw-------    1 root     sys           26 Jul 10 13:36 1 -> /hw/module/1/slot/n2/node
          lrw-------    1 root     sys           26 Jul 10 13:36 2 -> /hw/module/1/slot/n3/node
          lrw-------    1 root     sys           26 Jul 10 13:36 3 -> /hw/module/1/slot/n4/node
          lrw-------    1 root     sys           26 Jul 10 13:36 4 -> /hw/module/2/slot/n1/node
          lrw-------    1 root     sys           26 Jul 10 13:36 5 -> /hw/module/2/slot/n2/node
          lrw-------    1 root     sys           26 Jul 10 13:36 6 -> /hw/module/2/slot/n3/node
          lrw-------    1 root     sys           26 Jul 10 13:36 7 -> /hw/module/2/slot/n4/node

     The relation between cnodeids and node path names may change across
     reboots.

     There are two additional name spaces used internally by the operating
     system:  The Numa Address Space Identifier or nasids, which is used
     internally to define the section of the physical memory space that will
     be covered by a node; and the Persistent Node Identifier, which is used
     to identify hardware components. For a more detailed description, see the
     Origin Technical Report.

   Name Spaces for Processors
     The main name space for processors is provided by the hardware graph,
     where a name is a string of characters in the form of a path that both
     identifies a processor (CPU) and defines its location relative to the
     overall hardware.

          $ find /hw -name "[ab]" -print
          /hw/module/1/slot/n1/node/cpu/a
          /hw/module/1/slot/n1/node/cpu/b
          /hw/module/1/slot/n2/node/cpu/a
          /hw/module/1/slot/n2/node/cpu/b
          /hw/module/1/slot/n3/node/cpu/a
          /hw/module/1/slot/n3/node/cpu/b
          /hw/module/1/slot/n4/node/cpu/a
          /hw/module/1/slot/n4/node/cpu/b
          /hw/module/2/slot/n1/node/cpu/a
          /hw/module/2/slot/n1/node/cpu/b
          /hw/module/2/slot/n2/node/cpu/a
          /hw/module/2/slot/n2/node/cpu/b
          /hw/module/2/slot/n3/node/cpu/a
          /hw/module/2/slot/n3/node/cpu/b
          /hw/module/2/slot/n4/node/cpu/a
          /hw/module/2/slot/n4/node/cpu/b

     The listing above shows all processors in a system, and each path name
     also identifies the node the processor is connected to.

     Another name space for processors is the Compact Processor Identifiers,
     or simply cpuids. This space is just a compact enumeration of the
     processors currently available in the system, from 0 to NUMCPUS-1. Their
     relation to path names is defined by the hardware graph directory
     /hw/cpunum.

          $ cd /hw/cpunum
          $ ls -l
          total 0
          lrw-------    1 root     sys  32 Jul 10 14:53 0 -> /hw/module/1/slot/n1/node/cpu/a
          lrw-------    1 root     sys  32 Jul 10 14:53 1 -> /hw/module/1/slot/n1/node/cpu/b
          lrw-------    1 root     sys  32 Jul 10 14:53 10 -> /hw/module/2/slot/n2/node/cpu/a
          lrw-------    1 root     sys  32 Jul 10 14:53 11 -> /hw/module/2/slot/n2/node/cpu/b
          lrw-------    1 root     sys  32 Jul 10 14:53 12 -> /hw/module/2/slot/n3/node/cpu/a
          lrw-------    1 root     sys  32 Jul 10 14:53 13 -> /hw/module/2/slot/n3/node/cpu/b
          lrw-------    1 root     sys  32 Jul 10 14:53 14 -> /hw/module/2/slot/n4/node/cpu/a
          lrw-------    1 root     sys  32 Jul 10 14:53 15 -> /hw/module/2/slot/n4/node/cpu/b
          lrw-------    1 root     sys  32 Jul 10 14:53 2 -> /hw/module/1/slot/n2/node/cpu/a
          lrw-------    1 root     sys  32 Jul 10 14:53 3 -> /hw/module/1/slot/n2/node/cpu/b
          lrw-------    1 root     sys  32 Jul 10 14:53 4 -> /hw/module/1/slot/n3/node/cpu/a
          lrw-------    1 root     sys  32 Jul 10 14:53 5 -> /hw/module/1/slot/n3/node/cpu/b
          lrw-------    1 root     sys  32 Jul 10 14:53 6 -> /hw/module/1/slot/n4/node/cpu/a
          lrw-------    1 root     sys  32 Jul 10 14:53 7 -> /hw/module/1/slot/n4/node/cpu/b
          lrw-------    1 root     sys  32 Jul 10 14:53 8 -> /hw/module/2/slot/n1/node/cpu/a
          lrw-------    1 root     sys  32 Jul 10 14:53 9 -> /hw/module/2/slot/n1/node/cpu/b

     The relation between cpuids and cpu path names may change across reboots.

   Locality Management
     IRIX provides a rich set of features for managing memory locality, both
     automatically and manually. All automatic memory locality management
     procedures work based on the concept of adaptability; all manual tools
     work based on hints provided by users, compilers, or special high level
     memory placement tools.

   Automatic Memory Locality Management
     This capability is only available on Origin 2000/200 platforms. Any other
     Origin product line does not have automatic memory locality management.

     Automatic memory locality management in IRIX is based on dynamic memory
     migration (see migration(5)) and an initial placement policy based on a
     First Touch Placement Algorithm.  System administrators can tune the
     aggressiveness of both migration and replication for a system using the
     numa tunables file (/var/sysgen/mtune/numa) or the command sn(1).

   User Driven Memory Locality Management
     IRIX provides a Memory Management Control Interface (mmci(5)) to allow
     users control over memory system behavior. This interface covers both
     NUMA and generic memory system control. For NUMA, the interface provides
     control over placement, migration and replication policies; for generic
     memory management, the interface provides control over page size and
     paging algorithms.

     MMCI can be used directly (mmci(5)), via compiler directives (mp(3F),
     mp(3C)), or via high level placement tools (dplace(1), dplace(3),
     dplace(5), dprof(1)).

   Performance Monitoring
     Origin 2000/200 users can monitor memory reference patterns produced by
     their applications using the memory reference counters provided by the
     Origin 2000/200 hardware (refcnt(5)).  High level tools that simplify
     this procedure are dlook(1) and dprof(1).

     Users can also monitor the r10k event counters (r10k_counters(5)). See
     perfex(1), ssrun(1), speedshop(1).

 FILES

     /var/sysgen/mtune/numa

 SEE ALSO

     migration(5), mtune(4), refcnt(5), mmci(5), nstats(1), sn(1),
     topology(1), mld(3c), mldset(3c), pm(3c), migration(3c), pminfo(3c),
     numa_view(1), dplace(1), dprof(1).




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