illumos: manual page: prctl.1

PRCTL(1) User Commands PRCTL(1)

NAME

prctl - get or set the resource controls of running processes, tasks, and
projects

SYNOPSIS

prctl [-P] [-t [basic | privileged | system]]
[-n name [-srx] [-v value] [-e | -d action] [-p pid]]
[-i idtype] id...

DESCRIPTION

The prctl utility allows the examination and modification of the resource
controls associated with an active process, task, or project on the
system. It allows access to the basic and privileged limits and the
current usage on the specified entity.

See resource_controls(7) for a description of the resource controls
supported in the current release of the Solaris operating system.

OPTIONS

The following options are supported:

-d | -e action

Disables (-d) or enables (-e) the specified action on the resource
control value specified by -v, -t, and -p. If any of the -v, -t, or
-p options are unspecified, they match any value, privilege, or
recipient pid. For example, specifying only -v modifies the first
resource control with matching value, matching any privilege and
recipient pid. If no matching resource control value is found, a new
value is added as if -s were specified.

Actions:

all
This action is only available with -d. It disables
all actions. This fails on resource control values
that have the deny global flag.

deny
Indicates that the resource control attempts to deny
granting the resource to the process, task, project,
or zone on a request for resources in excess of the
resource control value. deny actions can not be
enabled if the resource control has the no-deny
global flag. deny actions can not be disabled if the
resource control has the deny global flag.

signal
This action is only available with -d. It
deactivates the signal action.

signal=signum
In the signal=signum action, signum is a signal
number (or string representation of a signal).
Setting a signal action on a resource control with
the no-local-action global flag fails. A limited set
of signals can be sent. See NOTES for additional
details.

-i idtype

Specifies the type of the id operands. Valid idtypes are process,
task, project, or zone. Also allowed are pid, taskid, projid, and
zoneid. The default id type, if the -i option is omitted, is process.

For a modify operation, the entity to which id operands are members
is the target entity. For instance, setting a project resource
control on an -i process sets the resource control on the project to
which each given process argument is a member.

For a get operation, the resource controls are listed for all
entities to which the id operands are members. For example, -i task
taskid lists the task, project, and zone resource controls for the
task, and for the project and zone to which that task is a member.

-n name

Specifies the name of the resource control to get or set. If the name
is unspecified, all resource controls are retrieved.

-p pid

When manipulating (using -s, -r, -x, -d, or -e) a basic task project,
or zone resource control values, a recipient pid can be specified
using -p. When setting a new basic resource control or controls on a
task, project, or zone, the -p option is required if the -i idtype
option argument is not process.

-P

Display resource control values in space delimited format.

-r

Replaces the first resource control value (matching with the -t
privilege) with the new value specified through the -v option.

-s

Set a new resource control value.

This option requires the -v option.

If you do not specify the -t option, basic privilege is used. If you
want to set a basic task, process, or zone rctl, -p is required. If
-e or -d are also specified, the action on the new rctl is set as
well.

For compatibility with prior releases, this option is implied if -v
is specified, without any of -e, -d, -r, or -x.

See resource_controls(7) for a description of unit modifiers and
scaling factors you can use to express large values when setting a
resource control value.

-t [ basic | privileged | system ]

Specifies which resource control type to set. Unless the "lowerable"
flag is set for a resource control, only invocations by users (or
setuid programs) who have privileges equivalent to those of root can
modify privileged resource controls. See rctlblk_set_value(3C) for a
description of the RCTL_GLOBAL_LOWERABLE flag. If the type is not
specified, basic is assumed. For a get operation, the values of all
resource control types, including system, are displayed if no type is
specified.

-v value

Specifies the value for the resource control for a set operation. If
no value is specified, then the modification (deletion, action
enabling or disabling) is carried out on the lowest-valued resource
control with the given type.

See resource_controls(7) for a description of unit modifiers and
scaling factors you can use to express large values when setting a
resource control value.

-x

Deletes the specified resource control value. If the delete option is
not provided, the default operation of prctl is to modify a resource
control value of matching value and privilege, or insert a new value
with the given privilege. The matching criteria are discussed more
fully in setrctl(2).

If none of the -s, -r, -x, -v, -d, or -e options are specified, the
invocation is considered a get operation. Otherwise, it is considered a
modify operation.

OPERANDS

The following operand is supported:

id
The ID of the entity (process, task, project, or zone) to
interrogate. If the invoking user's credentials are unprivileged
and the entity being interrogated possesses different credentials,
the operation fails. If no id is specified, an error message is
returned.

EXAMPLES

Example 1: Displaying Current Resource Control Settings

The following example displays current resource control settings for a
task to which the current shell belongs:

example$ ps -o taskid -p $$
TASKID
8
example$ prctl -i task 8
136150: /bin/ksh
NAME PRIVILEGE VALUE FLAG ACTION RECIPIENT
task.max-cpu-time
usage 8s
system 18.4Es inf none -
task.max-processes
usage 30
system 2.15G max deny -
task.max-lwps
usage 39
system 2.15G max deny -
project.max-contracts
privileged 10.0K - deny -
project.max-locked-memory
usage 0B
privileged 508MB - deny -
project.max-port-ids
privileged 8.19K - deny -
project.max-shm-memory
privileged 508MB - deny -
project.max-shm-ids
privileged 128 - deny -
project.max-msg-ids
privileged 128 - deny -
project.max-sem-ids
privileged 128 - deny -
project.max-crypto-memory
usage 0B
privileged 508MB - deny -
project.max-tasks
usage 2
system 2.15G max deny -
project.max-processes
usage 30
system 2.15G max deny -
project.max-lwps
usage 39
system 2.15G max deny -
project.cpu-shares
usage 1
privileged 1 - none -
zone.max-shm-memory
system 16.0EB max deny -
zone.max-shm-ids
system 16.8M max deny -
zone.max-sem-ids
system 16.8M max deny -
zone.max-msg-ids
system 16.8M max deny -
zone.max-processes
system 2.15G max deny -
zone.max-lwps
system 2.15G max deny -
zone.cpu-shares
privileged 1 - none -
zone.max-locked-memory
usage 0B
privileged 508MB - deny -

Example 2: Displaying, Replacing, and Verifying the Value of a Specific

Control

The following examples displays, replaces, and verifies the value of a
specific control on an existing project:

example# prctl -n project.cpu-shares -i project group.staff
project: 10: group.staff
NAME PRIVILEGE VALUE FLAG ACTION RECIPIENT
project.cpu-shares
usage 1
privileged 1 - none -
system 65.5K max none -

example# prctl -n project.cpu-shares -v 10 -r -i project group.staff
example# prctl -n project.cpu-shares -i project group.staff
project: 10: group.staff
NAME PRIVILEGE VALUE FLAG ACTION RECIPIENT
project.cpu-shares
usage 10
privileged 10 - none -
system 65.5K max none -

Example 3: Adjusting Resources

The following example uses the project.max-locked-memory resource.

First, use id -p to find out which project the current shell is a member
of:

/home/garfield> id -p
uid=77880(garfield) gid=10(staff) projid=10(group.staff)

Using the target project, identify the resource limit value before the
change:

/home/garfield> prctl -n project.max-locked-memory -i project \
group.staff
project 10: group.staff
project.max-locked-memory
privileged 256MB - deny -
system 16.0EB max deny -

current limit is 256 Megabytes.

Next, adjust the project.max-locked-memory limit to 300 Megabytes for the
target project:

# prctl -n project.max-locked-memory -v 300M -r -i project group.staff

The resource limit value after the change shows a new value of 300
Megabytes:

# prctl -n project.max-locked-memory -i project group.staff
project 10:group.staff
project.max-locked-memory
usage 200MG
privileged 300MB - deny -
system 16.0EB max deny -

Example 4: Modifying CPU Caps for a Project

The prctl command can use the project.cpu-cap resource control (see
resource_controls(7)) to set and modify CPU caps for a project. (The same
resource control can be used in the /etc/project file. See project(5))
The following command modifies the CPU cap to limit user.smith to three
CPUs:

# prctl -r -t privileged -n project.cpu-cap -v 300 -i project user.smith

The prctl -r option, used above, is used to dynamically change a CPU cap
for a project or zone. For example, the following command will change the
cap set in the preceding command to 80 percent:

# prctl -r -t privileged -n project.cpu-cap -v 80 -i project user.smith

To remove a CPU cap, enter:

# prctl -x -n project.cpu-cap $$

Example 5: Modifying CPU Caps for a Zone

The prctl command can use the zone.cpu-cap resource control (see
resource_controls(7)) to set and modify CPU caps for a zone. (The same
resource control can be manipulated using the zonecfg(8) command.) The
following command modifies the CPU cap to limit the global zone to 80
percent of a CPU:

# prctl -t privileged -n zone.cpu-cap -v 80 -i zone global

The cap can be lowered to 50% using:

# prctl -r -t privileged -n zone.cpu-cap -v 50 -i zone global

EXIT STATUS

The following exit values are returned:

0
Success.

1
Fatal error encountered.

2
Invalid command line options were specified.

FILES

/proc/pid/*
Process information and control files

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:

+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | See below. |
+--------------------+-----------------+

The command-line syntax is Committed. The human-readable output is
Uncommitted. The parsable output is Committed.

NOTES

The valid signals that can be set on a resource control block allowing
local actions are SIGABRT, SIGXRES, SIGHUP, SIGSTOP, SIGTERM, and
SIGKILL. Additionally, CPU time related controls can issue the SIGXCPU
signal, and file size related controls can send the SIGXFSZ signal.

January 23, 2021 PRCTL(1)