Tribblix: 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)