usr.bin/top/top.1

.Dd November 18, 2021
.Dt TOP 1
.Os
.Sh NAME
.Nm top
.Nd display and update information about the top cpu processes
.Sh SYNOPSIS
.Nm
.Op Fl abCHIijnPpqSTtuvxz
.Op Fl d Ar count
.Op Fl J Ar jail
.Op Fl m Ar mode
.Op Fl o Ar field
.Op Fl p Ar pid
.Op Fl s Ar time
.Op Fl U Ar uid
.Op Ar number
.Sh DESCRIPTION
.Nm
displays the top
processes on the system and periodically updates this information.
If standard output is an intelligent terminal (see below) then
as many processes as will fit on the terminal screen are displayed
by default.
Otherwise, a good number of them are shown (around 20).
Raw cpu percentage is used to rank the processes.
If
.Ar number
is given, then the top
.Ar number
processes will be displayed instead of the default.
.Pp
.Nm
makes a distinction between terminals that support advanced capabilities
and those that do not.
This distinction affects the choice of defaults for certain options.
In the remainder of this document, an
.Dq intelligent
terminal is one that
supports cursor addressing, clear screen, and clear to end of line.
Conversely, a
.Dq dumb
terminal is one that does not support such
features.
If the output of
.Nm
is redirected to a file, it acts as if it were being run on a dumb
terminal.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl a
Display command names derived from the argv[] vector, rather than real
executable name.
It it useful when you want to watch applications, that
puts their status information there.
If the real name differs from argv[0],
it will be displayed in parenthesis.
Non-printable characters in the command line are
encoded in C-style backslash sequences or
a three digit octal sequences.
.It Fl b
Use
.Dq batch
mode.
In this mode, all input from the terminal is
ignored.
Interrupt characters (such as ^C and ^\e) still have an effect.
This is the default on a dumb terminal, or when the output is not a terminal.
.It Fl C
Toggle CPU display mode.
By default top displays the weighted CPU percentage in the WCPU column
(this is the same value that
.Xr ps 1
displays as CPU).
Each time
.Fl C
flag is passed it toggles between
.Dq raw cpu
mode and
.Dq weighted cpu
mode, showing the
.Dq CPU
or the
.Dq WCPU
column respectively.
.It Fl d Ar count
Show only
.Ar count
displays, then exit.
A display is considered to be one update of the
screen.
The default is 1 for dumb terminals.
Note that for
.Ar count
= 1
no information is available about the percentage of time spent by the CPU in every state.
.It Fl H
Display each thread for a multithreaded process individually.
By default a single summary line is displayed for each process.
.It Fl I
Do not display idle processes.
By default, top displays both active and idle processes.
.It Fl i
Use
.Dq interactive
mode.
In this mode, any input is immediately
read for processing.
See the section on
.Dq Interactive Mode
for an explanation of
which keys perform what functions.
After the command is processed, the
screen will immediately be updated, even if the command was not
understood.
This mode is the default when standard output is an
intelligent terminal.
.It Fl J Ar jail
Show only those processes owned by
.Ar jail .
This may be either the
.Ar jid
or
.Ar name
of the jail.
Use
0
to limit to host processes.
Using this option implies
.Fl j .
.It Fl j
Display the
.Xr jail 8
ID.
.It Fl m Ar mode
Display statistics in the specified
.Ar mode .
Available modes are
.Cm cpu
and
.Cm io .
Default is
.Cm cpu .
.It Fl n
Use
.Dq non-interactive
mode.
This is identical to
.Dq batch
mode.
.It Fl o Ar field
Sort the process display area on the specified field.
The field name
is the name of the column as seen in the output, but in lower case:
.Dq cpu ,
.Dq size ,
.Dq res ,
.Dq time ,
.Dq pri ,
.Dq threads ,
.Dq total ,
.Dq read ,
.Dq write ,
.Dq fault ,
.Dq vcsw ,
.Dq ivcsw ,
.Dq jid ,
.Dq swap ,
or
.Dq pid .
.It Fl P
Display per-cpu CPU usage statistics.
.It Fl p Ar pid
Show only the process
.Ar pid .
.It Fl q
Renice
.Nm
to -20 so that it will run faster.
This can be used when the system is
being very sluggish to improve the possibility of discovering the problem.
This option can only be used by root.
.It Fl S
Show system processes in the display.
Normally, system processes such as the pager and the swapper are not shown.
This option makes them visible.
.It Fl s Ar time
Set the delay between screen updates to
.Ar time
seconds, which may be fractional.
The default delay between updates is 1 second.
.It Fl T
Toggle displaying thread ID (tid) instead of process id (pid).
.It Fl t
Do not display the
.Nm
process itself.
.It Fl U Ar username
Show only those processes owned by
.Ar username .
This option currently only accepts usernames and will not understand
uid numbers.
.It Fl u
Do not map uid numbers to usernames.
Normally,
.Nm
will read as much of the file
.Pa /etc/passwd
as is necessary to map
all the user id numbers it encounters into login names.
This option disables all that, while possibly decreasing execution time.
The uid numbers are displayed instead of the names.
.It Fl v
Write version number information to stderr then exit immediately.
.It Fl w
Display approximate swap usage for each process.
.It Fl z
Do not display the system idle process.
.El
.Pp
Both
.Ar count
and
.Ar number
fields can be specified as
.Dq infinite ,
indicating that they can
stretch as far as possible.
This is accomplished by using any proper
prefix of the keywords
.Dq infinity ,
.Dq maximum ,
or
.Dq all .
Boolean flags are toggles.
A second specification of any of these options will negate the first.
.Sh "INTERACTIVE MODE"
When
.Nm
is running in
.Dq interactive mode ,
it reads commands from the
terminal and acts upon them accordingly.
In this mode, the terminal is
put in
.Dq CBREAK ,
so that a character will be
processed as soon as it is typed.
Almost always, a key will be
pressed when
.Nm
is between displays; that is, while it is waiting for
.Ar time
seconds to elapse.
If this is the case, the command will be
processed and the display will be updated immediately thereafter
(reflecting any changes that the command may have specified).
This
happens even if the command was incorrect.
If a key is pressed while
.Nm
is in the middle of updating the display, it will finish the update and
then process the command.
Some commands require additional information,
and the user will be prompted accordingly.
While typing this information
in, the user's erase and kill keys (as set up by the command
.Xr stty 1 )
are recognized, and a newline terminates the input.
.Pp
These commands are currently recognized (^L refers to control-L):
.Bl -tag -width indent
.It ^L
Redraw the screen.
.It h
Display a summary of the commands (help screen).
Version information
is included in this display.
.It q
Quit
.Nm
.It d
Change the number of displays to show (prompt for new number).
Remember that the next display counts as one, so typing 'd1' will make
.Nm
show one final display and then immediately exit.
.It /
Display only processes that contain the specified string in their
command name.
If displaying arguments is enabled, the arguments are searched
too. '+' shows all processes.
.It m
Toggle the display between 'cpu' and 'io' modes.
.It n or #
Change the number of processes to display (prompt for new number).
.It s
Change the number of seconds to delay between displays
(prompt for new number).
.It S
Toggle the display of system processes.
.It a
Toggle the display of process titles.
.It k
Send a signal
.Pq SIGKILL by default
to a list of processes.
This acts similarly to the command
.Xr kill 1 .
.It r
Change the priority
.Pq the Dq nice
of a list of processes.
This acts similarly to
.Xr renice 8 .
.It u
Display only processes owned by a specific set of usernames (prompt for
username).
If the username specified is simply
.Dq +
or
.Dq - ,
then processes belonging to all users will be displayed.
Usernames can be added
to and removed from the set by prepending them with
.Dq +
and
.Dq - ,
respectively.
.It o
Change the order in which the display is sorted.
The sort key names include
.Dq cpu ,
.Dq res ,
.Dq size ,
and
.Dq time.
The default is cpu.
.It p
Display a specific process (prompt for pid).
If the pid specified is simply
.Dq + ,
then show all processes.
.It e
Display a list of system errors (if any) generated by the last
command.
.It H
Toggle the display of threads.
.It i or I
Toggle the display of idle processes.
.It j
Toggle the display of
.Xr jail 8
ID.
.It J
Display only processes owned by a specific jail (prompt for jail).
If the jail specified is simply
.Dq + ,
then processes belonging
to all jails and the host will be displayed.
This will also enable the display of JID.
.It P
Toggle the display of per-CPU statistics.
.It T
Toggle display of TID and PID
.It t
Toggle the display of the
.Nm
process.
.It w
Toggle the display of swap usage.
.It z
Toggle the display of the system idle process.
.El
.Sh "THE DISPLAY"
The top few lines of the display show general information
about the state of the system, including
the last process id assigned to a process (on most systems),
the three load averages,
the current time,
the number of existing processes,
the number of processes in each state
(sleeping, running, starting, zombies, and stopped),
and a percentage of time spent in each of the processor states
(user, nice, system, and idle).
It also includes information about physical and virtual memory allocation.
.Pp
The remainder of the screen displays information about individual
processes.
This display is similar in spirit to
.Xr ps 1
but it is not exactly the same.
PID is the process id,
JID, when displayed, is the
.Xr jail 8
ID corresponding to the process,
USERNAME is the name of the process's owner (if
.Fl u
is specified, a UID column will be substituted for USERNAME),
PRI is the current priority of the process,
NICE is the
.Xr nice 1
amount,
SIZE is the total size of the process (text, data, and stack),
RES is the current amount of resident memory,
SWAP is the approximate amount of swap, if enabled
(SIZE, RES and SWAP are given in kilobytes),
STATE is the current state (one of
.Dq START ,
.Dq RUN
(shown as
.Dq CPUn
on SMP systems),
.Dq SLEEP ,
.Dq STOP ,
.Dq ZOMB ,
.Dq WAIT ,
.Dq LOCK ,
or the event on which the process waits),
C is the processor number on which the process is executing
(visible only on SMP systems),
TIME is the number of system and user cpu seconds that the process has used,
WCPU, when displayed, is the weighted cpu percentage (this is the same
value that
.Xr ps 1
displays as CPU),
CPU is the raw percentage and is the field that is sorted to determine
the order of the processes, and
COMMAND is the name of the command that the process is currently running
(if the process is swapped out, this column is marked
.Dq <swapped> ) .
.Pp
If a process is in the
.Dq SLEEP
or
.Dq LOCK
state,
the state column will report the name of the event or lock on which the
process is waiting.
Lock names are prefixed with an asterisk
.Dq *
while sleep events
are not.
.Sh DESCRIPTION OF MEMORY
.Bd -literal
Mem: 61M Active, 86M Inact, 368K Laundry, 22G Wired, 102G Free
ARC: 15G Total, 9303M MFU, 6155M MRU, 1464K Anon, 98M Header, 35M Other
     15G Compressed, 27G Uncompressed, 1.75:1 Ratio, 174M Overhead
Swap: 4096M Total, 532M Free, 13% Inuse, 80K In, 104K Out
.Ed
.Ss Physical Memory Stats
.Bl -tag -width "Uncompressed" -compact
.It Em Active
number of bytes active
.It Em Inact
number of clean bytes inactive
.It Em Laundry
number of dirty bytes queued for laundering
.It Em Wired
number of bytes wired down, including IO-level cached file data pages
.It Em Buf
number of bytes used for IO-level disk caching
.It Em Free
number of bytes free
.El
.Ss ZFS ARC Stats
These stats are only displayed when the ARC is in use.
.Pp
.Bl -tag -width "Uncompressed" -compact
.It Em Total
number of wired bytes used for the ZFS ARC
.It Em MRU
number of ARC bytes holding most recently used data
.It Em MFU
number of ARC bytes holding most frequently used data
.It Em Anon
number of ARC bytes holding in flight data
.It Em Header
number of ARC bytes holding headers
.It Em Other
miscellaneous ARC bytes
.It Em Compressed
bytes of memory used by ARC caches
.It Em Uncompressed
bytes of data stored in ARC caches before compression
.It Em Ratio
compression ratio of data cached in the ARC
.El
.Ss Swap Stats
.Bl -tag -width "Uncompressed" -compact
.It Em Total
total available swap usage
.It Em Free
total free swap usage
.It Em Inuse
swap usage
.It Em \&In
bytes paged in from swap devices (last interval)
.It Em Out
bytes paged out to swap devices (last interval)
.El
.Sh ENVIRONMENT
.Bl -tag -width "Uncompressed"
.It Ev TOP
Default set of arguments to
.Nm .
.It Ev LC_CTYPE
The locale to use when displaying the
.Va argv
vector when
.Fl a
flag is specified.
.El
.Sh SEE ALSO
.Xr kill 1 ,
.Xr ps 1 ,
.Xr stty 1 ,
.Xr getrusage 2 ,
.Xr humanize_number 3 ,
.Xr mem 4 ,
.Xr renice 8
.Sh AUTHORS
.An William LeFebvre, EECS Department, Northwestern University
.Sh BUGS
The command name for swapped processes should be tracked down, but this
would make the program run slower.
.Pp
As with
.Xr ps 1 ,
things can change while
.Nm
is collecting information for an update.
The picture it gives is only a close approximation to reality.