numactl(8)
NAME
numactl - Control NUMA policy for processes or shared memory
SYNOPSIS
numactl [ --all ] [ --interleave nodes ] [ --preferred node ] [
--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 specifed 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 specifed 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
Always allocate 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. 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, --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 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.
--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=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 --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 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. 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
SEE ALSO
set_mempolicy(2) , get_mempolicy(2) , mbind(2) , sched_setaffinity(2) , sched_getaffinity(2) , proc(5) , ftok(3) , shmat(2) , migratepages(8)
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