LGRPINFO(1)

User Commands

LGRPINFO(1)

NAME

lgrpinfo - display information about locality groups

SYNOPSIS

lgrpinfo [-aceGlLmrt] [-u unit] [-C | -P] lgrp ...

lgrpinfo -h

lgrpinfo -I [-c] [-G] [-C | -P] lgrp ...

lgrpinfo [-T] [-aceGlLmr] [-u unit]

DESCRIPTION

lgrpinfo prints information about the locality group (lgroup) hierarchy and its contents.

An lgroup represents the set of CPU and memory-like hardware devices that are at most some distance (latency) apart from each other. All lgroups in the system are identified by a unique integer called an lgroup ID.

lgroups are organized into a hierarchy to facilitate finding the nearest resources. Leaf lgroups each contain a set of resources that are closest (local) to each other. Each parent lgroup in the hierarchy contains the resources of its child lgroups plus their next nearest resources. Finally, the root lgroup contains all the resources in the domain within the largest latency.

A Uniform Memory Access (UMA) machine is simply represented by the root lgroup. A Non Uniform Memory Access (NUMA) machine is represented by a hierarchy of lgroups to show the corresponding levels of locality. For example, a NUMA machine with two latencies (local and remote) has an lgroup hierarchy consisting of two levels with its leaves and the root.

Every application thread is assigned a home lgroup. When the system needs to allocate a CPU or memory resource for a thread, it searches lgroup hierarchy from the thread's home lgroup for the closest available resources to the thread's home. See plgrp(1) for details.

Without arguments, lgrpinfo prints general information about all lgroups in the system. If any lgroup IDs are specified on the command line, the command only prints information about the specified lgroups. Various options control which lgroups are displayed and the exact information that is printed for each lgroup.

lgroups can be specified on the command line as lgroup IDs or by using specific keywords. See OPERANDS.

OPTIONS

You can combine options together and the order in which options are specified is not important. Lowercase options select what information should be printed about lgroups.

Invoking lgrpinfo without arguments is equivalent to:

lgrpinfo -c -e -l -m -r -t all

The following options are supported:

-a

Print topology, CPU, memory, load and latency information.

This option is a shorthand for

lgrpinfo -t -c -e -m -r -l -L

unless -T is specified as well. When -T is specified, the -t option is not included.

-c

Print CPU information.

This is the default.

-C

Replace each lgroup in the list with its children.

This option cannot be used with the -P or the -T option. When no arguments are specified, this option is applied to the lgroups displayed by default.

-e

Print lgroup load average. The lgroup load averages are only displayed for leaf lgroups.

This is the default.

-G

Print OS view of lgroup hierarchy.

By default, the caller's view of the lgroup hierarchy is displayed which only includes what the caller can use, for example, only the CPUs in the caller's processor set is displayed. See lgrp_init(3LGRP) on the operating system and the caller's view.

-h

Print short help message and exit.

-I

Print matching IDs only.

This option is intended for scripts and can be used with -c, -G, and -C or -P. If -c is specified, print list of CPUs contained in all matching lgroups. Otherwise, the IDs for the matching lgroups is displayed. See EXAMPLES.

When no arguments are specified, this option is applied to the lgroups displayed, which, by default is all lgroups.

-l

Print information about lgroup latencies.

The latency value specified for each lgroup is defined by the operating system and is platform-specific. It can only be used for relative comparison of lgroups on the running system. It does not necessarily represent the actual latency between hardware devices and might not be applicable across platforms.

-L

Print the lgroup latency table. The lgroup latency table displays the relative latency from each lgroup to each of the other lgroups including itself.

-m

Print memory information.

Memory sizes are scaled to the unit of measure that yields an integer from 0 to 1023 unless the -u option is specified as well. The fractional part of the number is only displayed for values less than 10. This behavior is similar to using the -h option of ls(1) or df(1M) to display a human readable format.

This is the default.

-P

Replace each lgroup in the list with its parents.

This option cannot be used with the -C or -T option. When no arguments are specified, this option is applied to the lgroups displayed, which, by default is all lgroups.

-r

Print information about lgroup resources.

The resources are represented by a set of lgroups in which each member lgroup directly contains CPU and memory resources. If -T is specified as well, only information about resources of the intermediate lgroups is displayed.

-t

Print information about lgroup topology.

This is the default.

-T

Print the lgroup topology of a system graphically as a tree. This option can only be used with the -a, -c, -e, -G, -l,-L, -m, -r, and -u options. It only prints lgroup resources for intermediate lgroups when used with the -r. The -t option is omitted when -T is used with -a. No information is printed for the root lgroup unless it is the only lgroup.

-u units

Specify memory units. Units should be b, k, m, g, t, p, or e for bytes, kilobytes, megabytes, gigabytes, terabytes, petabytes, or exabytes respectively. The fractional part of the number is only displayed for values less than 10. This behavior is similar to using the -h option of ls(1) or df(1M) to display a human readable format.

OPERANDS

The following operands are supported:

lgrp

lgroups can be specified on the command line as lgroup ID, by using one of the following keywords:

all

All lgroups.

This is the default.

intermediate

All intermediate lgroups. An intermediate lgroup is an lgroup that has a parent and children.

leaves

All leaf lgroups. A leaf lgroup is an lgroup that has no children in the lgroup hierarchy.

root

Root lgroup. Root lgroup contains all the resources in the domain within the largest latency and has no parent lgroup.

If an invalid lgroup is specified, the lgrpinfo command prints a message on standard error showing the invalid ID and continues processing other lgroups specified on the command line. When none of the specified lgroups are valid, lgrpinfo exits with an exit status of 2.

EXAMPLES

Example 1 Printing Information about lgroups

The following example prints general information about lgroups in the system.

In this example, the system is a 2 CPU AMD Opteron machine with two nodes, each having one CPU and 2 gigabytes of memory. Each of these nodes is represented by a leaf lgroup. The root lgroup contains all the resources in the machine:

$ lgrpinfo
lgroup 0 (root):
Children: 1 2
CPUs: 0 1
Memory: installed 4.0G, allocated 2.2G, free 1.8G
Lgroup resources: 1 2 (CPU); 1 2 (memory)
Latency: 83
lgroup 1 (leaf):
Children: none, Parent: 0
CPU: 0
Memory: installed 2.0G, allocated 1.2G, free 788M
Lgroup resources: 1 (CPU); 1 (memory)
Load: 0.793
Latency: 56
lgroup 2 (leaf):
Children: none, Parent: 0
CPU: 1
Memory: installed 2.0G, allocated 1017M, free 1.0G
Lgroup resources: 2 (CPU); 2 (memory)
Load: 0.817
Latency: 56

Example 2 Printing lgroup Topology

The following example prints the lgroup topology tree on a 4 CPU AMD Opteron machine:

$ lgrpinfo -T
0
|-- 5
| `-- 1
|-- 6
| `-- 2
|-- 7
| `-- 3
`-- 8
`-- 4

Example 3 Printing lgroup Topology

The following example prints the lgroup topology tree, resources, memory and CPU information on a 2 CPU AMD Opteron machine:

Lgroup latencies:

------------
| 0 1 2
------------
0 | 83 83 83
1 | 83 56 83
2 | 83 83 56
------------

Example 4 Printing lgroup IDs

The following example prints lgroup IDs for children of the root lgroup:

$ lgrpinfo -I -C root
1 2

Example 5 Printing CPU IDs

The following example prints CPU IDs for all CPUs in lgroup 1:

$ lgrpinfo -c -I 1
0

Example 6 Printing Information about lgroup Latencies

The following example prints information about lgroup latencies:

$ lgrpinfo -l
lgroup 0 (root):
Latency: 83
lgroup 1 (leaf):
Latency: 56
lgroup 2 (leaf):
Latency: 5

EXIT STATUS

The following exit values are returned:

Successful completion.

Unable to get lgroup information from the system.

All lgroups specified are invalid.

Invalid syntax.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE

Interface Stability	See below.

The human readable output is Unstable.

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

OPERANDS

EXAMPLES

EXIT STATUS

ATTRIBUTES

SEE ALSO