numactl



NUMACTL(8)               Linux Administrator’s Manual               NUMACTL(8)




NAME

       numactl - Control NUMA policy for processes or shared memory


SYNOPSIS

       numactl [ --interleave nodes ] [ --preferred node ] [ --membind nodes ]
       [ --cpubind nodes ] [ --localalloc ] command {arguments ...}
       numactl --show
       numactl --hardware
       numactl [ --huge ] [ --offset offset ] [ --mode shmmode  ]  [  --length
       length ] [ --strict ]
       --shmid id | --shm shmkeyfile | --file tmpfsfile
       [ --touch ] [ --dump ] memory policy


DESCRIPTION

       numactl runs processes with a specific NUMA scheduling or memory place-
       ment policy.  The policy is set for command and inherited by all of its
       children.   In  addition it can set persistent policy for shared memory
       segments or files.

       Policy settings are:

       --interleave=nodes, -i nodes
              Set an memory interleave policy. Memory will be allocated  using
              round  robin  on  nodes.  When memory cannot be allocated on the
              current interleave target fall back to other nodes.

       --membind=nodes, -m nodes
              Only allocate memory from  nodes.   Allocation  will  fail  when
              there is not enough memory available on these nodes.

       --cpubind=nodes, -c nodes
              Only execute process on the CPUs of nodes.

       --localalloc, -l
              Do always local allocation on the current node.

       --preferred=node
              Preferably  allocate  memory  on  node,  but if memory cannot be
              allocated there fall back to other  nodes.   This  option  takes
              only a single node number.

       --show, -s
              Show NUMA policy settings of the current process.

       --hardware, -H
              Show inventory of available nodes on the system.

       Numactl can set up policy for a SYSV shared memory segment or a file in
       shmfs/hugetlbfs.

       This  policy  is  persistent and will be used by all mappings from that
       shared memory. The order of options matters  here.   The  specification
       must  at  least include either of --shm, --shmid, --file to specify the
       shared memory segment or file and a memory policy like described  above
       ( --interleave, --localalloc, --prefered, --membind ).

       --huge
       When  creating a SYSV shared memory segment use huge pages.  Only valid
       before --shmid or --shm

       --offset
       Specify offset into the shared memory segment. Default 0.  Valid  units
       are m (for MB), g (for GB), k (for KB), otherwise it specifies bytes.

       --strict
       Give  an  error  when  a page in the policied area in the shared memory
       segment already was faulted in with a conflicting policy. Default is to
       silently ignore this.

       --mode shmmode
       Only  valid  before --shmid or --shm When creating a shared memory seg-
       ment set it to numeric mode shmmode.

       --length length
       Apply policy to length range in the shared memory segment or  make  the
       segment  length  long  Default  is to use the remaining length Required
       when a shared memory segment is created and specifies the length of the
       new  segment  then. Valid units are m (for MB), g (for GB), k (for KB),
       otherwise it specifies bytes.

       --shmid id
       Create or use an shared memory segment with numeric ID id

       --shm shmkeyfile
       Create or use an shared memory segment, with  the  ID  generated  using
       ftok(3) from shmkeyfile

       --file tmpfsfile
       Set policy for a file in tmpfs or hugetlbfs

       --touch
       Touch  pages to enforce policy early. Default is to not touch them, the
       policy is applied when an applications maps and accesses a page.

       --dump
       Dump policy in the specified range.

       Valid node specifiers

       all                 All nodes
       number              Node number
       number1{,number2}   Node number1 and Node number2
       number1-number2     Nodes from number1 to number2
       ! nodes             Invert selection of the following specification.


EXAMPLES

       numactl --interleave=all bigdatabase arguments Run  big  database  with
       its memory interleaved on all CPUs.

       numactl  --cpubind=0--membind=0,1  process  Run  process on node 0 with
       memory allocated on node 0 and 1.

       numactl --preferred=1 numactl --show Set preferred node 1 and show  the
       resulting state.

       numactl --interleave=all --shmkeyfile /tmp/shmkey Interleave all of the
       sysv shared memory regiion specified by /tmp/shmkey over all nodes.

       numactl --offset=1G --length=1G --membind=1 --file  /dev/shm/A  --touch
       Bind the second gigabyte in the tmpfs file /dev/shm/A to node 1.

       numactl --localalloc /dev/shm/file Reset the policy for the shared mem-
       ory file file to the default localalloc policy.


NOTES

       Requires an NUMA policy aware kernel.

       Command is not executed using  a  shell.  If  you  want  to  use  shell
       metacharacters in the child use sh -c as wrapper.

       Setting  policy for a hugetlbfs file does currently not work because it
       cannot be extended by truncate.

       Shared memory segments larger than numactl’s address  space  cannot  be
       completely  policied.  This  could be a problem on 32bit architectures.
       Changing it piece by piece may work.



FILES

       /proc/cpuinfo for the listing of active CPUs. See proc(5) for  details.

       /sys/devices/system/node/node*/numastat for NUMA memory hit statistics.



COPYRIGHT

       Copyright 2002,2004 Andi Kleen, SuSE Labs.  numactl and the  demo  pro-
       grams are under the GNU General Public License, v.2



SEE ALSO

       set_mempolicy(2) , get_mempolicy(2) , mbind(2) , sched_setaffinity(2) ,
       sched_getaffinity(2) , proc(5) , ftok(3) , shmat(2)



SuSE Labs                          Mar 2004                         NUMACTL(8)

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