numad¶

numad - A user-level daemon that provides placement advice and process management for efficient use of CPUs and memory on systems with NUMA topology.

SYNTAX¶

numad [-dFhvV]

numad [-D non-standard-cgroup-mount-point]

numad [-i [min_interval:]max_interval]

numad [-K 0|1]

numad [-l log_level]

numad [-p PID]

numad [-r PID]

numad [-S 0|1]

numad [-u target_utilization]

numad [-w NCPUS[:MB]]

numad [-x PID]

DESCRIPTION¶

Numad is a system daemon that monitors NUMA topology and resource usage. It will attempt to locate processes for efficient NUMA locality and affinity, dynamically adjusting to changing system conditions. Numad also provides guidance to assist management applications with initial manual binding of CPU and memory resources for their processes. Note that numad is primarily intended for server consolidation environments, where there might be multiple applications or multiple virtual guests running on the same server system. Numad is most likely to have a positive effect when processes can be localized in a subset of the system's NUMA nodes. If the entire system is dedicated to a large in-memory database application, for example -- especially if memory accesses will likely remain unpredictable -- numad will probably not improve performance.

OPTIONS¶

-d

Debug output in log, sets the log level to LOG_DEBUG. Same effect as -l 7.

-D <non-standard-cgroup-mount-point>

This option can be used to communicate a non-standard cgroup mount point to numad. This is not normally necessary.

-F

Run in foreground mode, do not daemonize.

-h

Display usage help information and then exit.

-i <[min_interval:]max_interval>

Sets the time interval that numad waits between system scans, in seconds to <max_interval>. Default <max_interval> is 15 seconds, default <min_interval> is 5 seconds. Setting a <max_interval> of zero will cause the daemon to exit. (This is the normal mechanism to terminate the daemon.) A bigger <max_interval> will decrease numad overhead but also decrease responsiveness to changing loads.

-K <0|1>

This option controls whether numad keeps interleaved memory spread across NUMA nodes, or attempts to merge interleaved memory to local NUMA nodes. The default is to merge interleaved memory. This is the appropriate setting to localize processes in a subset of the system's NUMA nodes. If you are running a large, single-instance application that allocates interleaved memory because the workload will have continuous unpredictable memory access patterns (e.g. a large in-memory database), you might get better results by specifying -K 1 to instruct numad to keep interleaved memory distributed.

-l <log_level>

Sets the log level to <log_level>. Reasonable choices are 5, 6, or 7. The default value is 5.

-p <PID>

Add PID to explicit inclusion list of processes to consider for managing, if the process also uses significant resources. Multiple -p PID options can be specified at daemon start, but after daemon start, only one PID can be added to the inclusion list per subsequent numad invocation. Use with -S to precisely control the scope of processes numad can manage. Note that the specified process will not necessarily be actively managed unless it also meets numad's significance threshold -- which is currently 300MB and half of a CPU.

-r <PID>

Remove PID from both the explicit inclusion and the exclusion lists of processes. After daemon start, only one PID can be removed from the explicit process lists per subsequent numad invocation. Use with -S and -p and -x to precisely control the scope of processes numad can manage.

-S <0|1>

This option controls whether numad scans all system processes or only the processes on the explicit inclusion PID list. The default is to scan all processes. Use -S 0 to scan only the explicit inclusion PID list. Use -S 1 to again scan all system processes (excepting those on the explicit exclusion list). Starting numad as
numad -S 0 -p <PID-1> -p <PID-2> -p <PID-3>
will limit scanning, and thus also automatic NUMA management, to only those three explicitly specified processes.

-u <target_utilization>

Set the desired maximum consumption percentage of a node. Default is 85%. Decrease the target value to maintain more available resource margin on each node. Increase the target value to more exhaustively consume node resources.

-v

Verbose output in log, sets the log level to LOG_INFO. Same effect as -l 6.

-V

Display version information and exit.

-w <NCPUS[:MB]>

Queries numad for the best NUMA nodes to bind an entity that needs <NCPUS>. The amount of memory (in MBs) is optional, but should normally be specified as well <:MB> so numad can recommend NUMA nodes with available CPU capacity and adequate free memory. This query option can be used regardless of whether numad is running as a daemon. (An invocation using this option when numad is not running as a daemon, will not cause the daemon to start.) Output of this option is a string that contains a NUMA node list. For example: 2-3,6. The recommended node list could be saved in a shell variable (e.g., NODES) and then used as the node list parameter in a
numactl -m $NODES -N $NODES ...
command. See numactl(8).

-x <PID>

Add PID to explicit exclusion list of processes to blacklist from managing. Multiple -x PID options can be specified at daemon start, but after daemon start, only one PID can be added to the exclusion list per subsequent numad invocation. Use with -S to precisely control the scope of processes numad can manage.

FILES¶

/usr/bin/numad
/var/log/numad.log
/var/run/numad.pid

ENVIRONMENT VARIABLES¶

None.

EXAMPLES¶

Numad is normally run as a system daemon and should be managed by the standard init mechanisms of the host.

If interactive (manual) control is desired, you can start the daemon manually by typing:

/usr/bin/numad

Subsequent numad invocations while the daemon is running can be used to dynamically change run-time options.

AUTHORS¶

Bill Gray <bgray@redhat.com>

SEE ALSO¶

numactl(8)