NAME¶
numactl - Control NUMA policy for processes or shared memory
SYNOPSIS¶
numactl [
--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:
- --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 --nodebind=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 --shmkeyfile /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)