Ubuntu Manpage: numactl - Control NUMA policy for processes or shared memory

NAME

       numactl - Control NUMA policy for processes or shared memory

SYNOPSIS

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

DESCRIPTION

numactl runs processes with a specific NUMA scheduling or memory placement 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.

Use -- before command if using command options that could be confused with numactl
options.

nodes may be specified as N,N,N or N-N or N,N-N or N-N,N-N and so forth. Relative nodes
may be specified as +N,N,N or +N-N or +N,N-N and so forth. The + indicates that the node
numbers are relative to the process' set of allowed nodes in its current cpuset. A !N-N
notation indicates the inverse of N-N, in other words all nodes except N-N. If used with
+ notation, specify !+N-N. When same is specified the previous nodemask specified on the
command line is used. all means all nodes in the current cpuset.

Instead of a number a node can also be:

netdev:DEV The node connected to network device DEV.
file:PATH The node the block device of PATH.
ip:HOST The node of the network device of HOST
block:PATH The node of block device PATH
pci:[seg:]bus:dev[:func] The node of a PCI device.

Note that block resolves the kernel block device names only for udev names in /dev use
file:

Policy settings are:

--all, -a
Unset default cpuset awareness, so user can use all possible CPUs/nodes for
following policy settings.

--interleave=nodes, -i nodes
Set a 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. Multiple nodes may be specified on --interleave, --membind and
--cpunodebind.

--membind=nodes, -m nodes
Only allocate memory from nodes. Allocation will fail when there is not enough
memory available on these nodes. nodes may be specified as noted above.

--cpunodebind=nodes, -N nodes
Only execute command on the CPUs of nodes. Note that nodes may consist of multiple
CPUs. nodes may be specified as noted above.

--physcpubind=cpus, -C cpus
Only execute process on cpus. This accepts cpu numbers as shown in the processor
fields of /proc/cpuinfo, or relative cpus as in relative to the current cpuset.
You may specify "all", which means all cpus in the current cpuset. Physical cpus
may be specified as N,N,N or N-N or N,N-N or N-N,N-N and so forth. Relative cpus
may be specified as +N,N,N or +N-N or +N,N-N and so forth. The + indicates that
the cpu numbers are relative to the process' set of allowed cpus in its current
cpuset. A !N-N notation indicates the inverse of N-N, in other words all cpus
except N-N. If used with + notation, specify !+N-N.

--localalloc, -l
Try to allocate on the current node of the process, but if memory cannot be
allocated there fall back to other nodes.

--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. Relative
notation may be used.

--balancing, -b
Enable Linux kernel NUMA balancing for the process if it is supported by kernel.
This should only be used with --membind, -m only, otherwise ignored.

--preferred-many=node
Preferably allocate memory on nodes, but if memory cannot be allocated there fall
back to other nodes. This option takes a mask of preferred nodes where the closest
node to local is considered most preferred. Relative notation may be used.

--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, --preferred, --preferred-many, --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.

--shmmode shmmode
Only valid before --shmid or --shm When creating a shared memory segment 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 a shared memory segment with numeric ID id

--shm shmkeyfile
Create or use a 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.

--dump-nodes
Dump all nodes of the specific range (very verbose!)

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  --physcpubind=+0-4,8-12  myapplic  arguments Run myapplic on cpus 0-4 and 8-12 of
       the current cpuset.

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

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

       numactl --cpunodebind=0 --membind=0,1 -- process -l Run process  as  above,  but  with  an
       option (-l) that would be confused with a numactl option.

       numactl  --cpunodebind=0  --balancing  --membind=0,1  process  Run  process on node 0 with
       memory allocated on node 0 and 1.  Optimize the page  placement  with  Linux  kernel  NUMA
       balancing mechanism if possible.

       numactl  --cpunodebind=netdev:eth0 --membind=netdev:eth0 network-server Run network-server
       on the node of network device eth0 with its memory also in the same node.

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

       numactl --preferred-many=0x3 numactl --show Set preferred nodes 1  and  2,  and  show  the
       resulting state.

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

       Place a tmpfs file on 2 nodes:
         numactl --membind=2 dd if=/dev/zero of=/dev/shm/A bs=1M count=1024
         numactl --membind=3 dd if=/dev/zero of=/dev/shm/A seek=1024 bs=1M count=1024

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

NOTES

       Requires a 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.

       The old --cpubind which accepts node numbers, not cpu numbers, is deprecated and  replaced
       with the new --cpunodebind and --physcpubind options.

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 programs are under the
       GNU General Public License, v.2