freebsd-dev/usr.bin/rctl/rctl.8

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.Dd February 26, 2018
.Dt RCTL 8
.Os
.Sh NAME
.Nm rctl
.Nd display and update resource limits database
.Sh SYNOPSIS
.Nm
.Op Fl h
.Op Fl n
.Op Ar filter Ar ...
.Nm
.Fl a
.Ar rule Ar ...
.Nm
.Fl l
.Op Fl h
.Op Fl n
.Ar filter Ar ...
.Nm
.Fl r
.Ar filter Ar ...
.Nm
.Fl u
.Op Fl h
.Ar filter Ar ...
.Sh DESCRIPTION
When called without options, the
.Nm
command writes currently defined RCTL rules to standard output.
.Pp
If a
.Ar filter
argument is specified, only rules matching the filter are displayed.
The options are as follows:
.Bl -tag -width indent
.It Fl a Ar rule
Add
.Ar rule
to the RCTL database.
.It Fl l Ar filter
Display rules applicable to the process defined by
.Ar filter .
Note that this is different from showing the rules when called without
any options, as it shows not just the rules with subject equal to that
of process, but also rules for the user, jail, and login class applicable
to the process.
.It Fl r Ar filter
Remove rules matching
.Ar filter
from the RCTL database.
.It Fl u Ar filter
Display resource utilization for a subject
.Po
.Sy process ,
.Sy user ,
.Sy loginclass
or
.Sy jail
.Pc
matching the
.Ar filter .
.It Fl h
"Human-readable" output.
Use unit suffixes: Byte, Kilobyte, Megabyte,
Gigabyte, Terabyte and Petabyte.
.It Fl n
Display user IDs numerically rather than converting them to a user name.
.El
.Pp
Modifying rules affects all currently running and future processes matching
the rule.
.Sh RULE SYNTAX
Syntax for a rule is subject:subject-id:resource:action=amount/per.
.Pp
.Bl -tag -width "subject-id" -compact -offset indent
.It subject
defines the kind of entity the rule applies to.
It can be either
.Sy process ,
.Sy user ,
.Sy loginclass ,
or
.Sy jail .
.It subject-id
identifies the
.Em subject .
It can be a process ID, user name, numerical user ID, login class name from
.Xr login.conf 5 ,
or jail name.
.It resource
identifies the resource the rule controls.
See the
.Sx RESOURCES
section below for details.
.It action
defines what will happen when a process exceeds the allowed
.Em amount .
See the
.Sx ACTIONS
section below for details.
.It amount
defines how much of the resource a process can use before
the defined
.Em action
triggers.
Resources which limit bytes may use prefixes from
.Xr expand_number 3 .
.It per
defines what entity the
.Em amount
gets accounted for.
For example, rule "loginclass:users:vmem:deny=100M/process" means
that each process of any user belonging to login class "users" may allocate
up to 100MB of virtual memory.
Rule "loginclass:users:vmem:deny=100M/user" would mean that for each
user belonging to the login class "users", the sum of virtual memory allocated
by all the processes of that user will not exceed 100MB.
Rule "loginclass:users:vmem:deny=100M/loginclass" would mean that the sum of
virtual memory allocated by all processes of all users belonging to that login
class will not exceed 100MB.
.El
.Pp
A valid rule has all those fields specified, except for
.Em per ,
which defaults
to the value of
.Em subject .
.Pp
A filter is a rule for which one of more fields other than
.Em per
is left empty.
For example, a filter that matches every rule could be written as ":::=/",
or, in short, ":".
A filter that matches all the login classes would be "loginclass:".
A filter that matches all defined rules for
.Sy maxproc
resource would be
"::maxproc".
.Sh SUBJECTS
.Bl -column -offset 3n "pseudoterminals" ".Sy username or numerical User ID"
.It Sy process Ta numerical Process ID
.It Sy user Ta user name or numerical User ID
.It Sy loginclass Ta login class from
.Xr login.conf 5
.It Sy jail Ta jail name
.El
.Sh RESOURCES
.Bl -column -offset 3n "pseudoterminals"
.It Sy cputime Ta "CPU time, in seconds"
.It Sy datasize Ta "data size, in bytes"
.It Sy stacksize Ta "stack size, in bytes"
.It Sy coredumpsize Ta "core dump size, in bytes"
.It Sy memoryuse Ta "resident set size, in bytes"
.It Sy memorylocked Ta "locked memory, in bytes"
.It Sy maxproc Ta "number of processes"
.It Sy openfiles Ta "file descriptor table size"
.It Sy vmemoryuse Ta "address space limit, in bytes"
.It Sy pseudoterminals Ta "number of PTYs"
.It Sy swapuse Ta "swap space that may be reserved or used, in bytes"
.It Sy nthr Ta "number of threads"
.It Sy msgqqueued Ta "number of queued SysV messages"
.It Sy msgqsize Ta "SysV message queue size, in bytes"
.It Sy nmsgq Ta "number of SysV message queues"
.It Sy nsem Ta "number of SysV semaphores"
.It Sy nsemop Ta "number of SysV semaphores modified in a single semop(2) call"
.It Sy nshm Ta "number of SysV shared memory segments"
.It Sy shmsize Ta "SysV shared memory size, in bytes"
.It Sy wallclock Ta "wallclock time, in seconds"
.It Sy pcpu Ta "%CPU, in percents of a single CPU core"
.It Sy readbps Ta "filesystem reads, in bytes per second"
.It Sy writebps Ta "filesystem writes, in bytes per second"
.It Sy readiops Ta "filesystem reads, in operations per second"
.It Sy writeiops Ta "filesystem writes, in operations per second"
.El
.Sh ACTIONS
.Bl -column -offset 3n "pseudoterminals"
.It Sy deny Ta deny the allocation; not supported for
.Sy cputime ,
.Sy wallclock ,
.Sy readbps ,
.Sy writebps ,
.Sy readiops ,
and
.Sy writeiops
.It Sy log Ta "log a warning to the console"
.It Sy devctl Ta "send notification to"
.Xr devd 8
using
.Sy system
= "RCTL",
.Sy subsystem
= "rule",
.Sy type
= "matched"
.It sig*	e.g.
.Sy sigterm ;
send a signal to the offending process.
See
.Xr signal 3
for a list of supported signals
.It Sy throttle Ta "slow down process execution"; only supported for
.Sy readbps ,
.Sy writebps ,
.Sy readiops ,
and
.Sy writeiops .
.El
.Pp
Not all actions are supported for all resources.
Attempting to add a rule with an action not supported by a given resource will
result in error.
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
Prevent user "joe" from allocating more than 1GB of virtual memory:
.Dl Nm Fl a Ar user:joe:vmemoryuse:deny=1g
.Pp
Remove all RCTL rules:
.Dl Nm Fl r Ar \&:
.Pp
Display resource utilization information for jail named "www":
.Dl Nm Fl hu Ar jail:www
.Pp
Display all the rules applicable to process with PID 512:
.Dl Nm Fl l Ar process:512
.Pp
Display all rules:
.Dl Nm
.Pp
Display all rules matching user "joe":
.Dl Nm Ar user:joe
.Pp
Display all rules matching login classes:
.Dl Nm Ar loginclass:
.Sh SEE ALSO
.Xr cpuset 1 ,
.Xr rctl 4 ,
.Xr rctl.conf 5
.Sh HISTORY
The
.Nm
command appeared in
.Fx 9.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
was developed by
.An Edward Tomasz Napierala Aq Mt trasz@FreeBSD.org
under sponsorship from the FreeBSD Foundation.
.Sh BUGS
Limiting
.Sy memoryuse
may kill the machine due to thrashing.
.Pp
The
.Sy readiops
and
.Sy writeiops
counters are only approximations.
Like
.Sy readbps
and
.Sy writebps ,
they are calculated in the filesystem layer, where it is difficult
or even impossible to observe actual disk device operations.
.Pp
The
.Sy writebps
and
.Sy writeiops
resources generally account for writes to the filesystem cache,
not to actual devices.