display and update information about the top cpu
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
is given, then the top
processes will be displayed instead of
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 “intelligent” terminal is one that supports cursor
addressing, clear screen, and clear to end of line. Conversely, a
“dumb” terminal is one that does not support such features. If
the output of
is redirected to a file,
it acts as if it were being run on a dumb terminal.
- Toggle CPU display mode. By default top displays the weighted CPU
percentage in the WCPU column (this is the same value that
displays as CPU). Each time
- flag is passed it toggles between “raw cpu” mode and
“weighted cpu” mode, showing the “CPU” or the
“WCPU” column respectively.
- Show system processes in the display. Normally, system processes such as
the pager and the swapper are not shown. This option makes them
- 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, it will be displayed in parenthesis.
- Use “batch” mode. In this mode, all input from the terminal
is ignored. Interrupt characters (such as ^C and ^\) still have an effect.
This is the default on a dumb terminal, or when the output is not a
- Display each thread for a multithreaded process individually. By default a
single summary line is displayed for each process.
- Use “interactive” mode. In this mode, any input is
immediately read for processing. See the section on “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.
- Do not display idle processes. By default, top displays both active and
- Display the
- Toggle displaying thread ID (tid) instead of process id (pid).
- Do not display the
- Display either 'cpu' or 'io' statistics. Default is 'cpu'.
- Use “non-interactive” mode. This is identical to
- Display per-cpu CPU usage statistics.
top 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
- Do not map uid numbers to usernames. Normally,
top will read as much of the file
“/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.
- Write version number information to stderr then exit immediately.
- Display approximate swap usage for each process.
- Do not display the system idle process.
- Show only 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 count = 1
no information is available about the percentage of time spent by the CPU
in every state.
- Set the delay between screen updates to
time seconds. The default delay between
updates is 1 second.
- 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:
“cpu“, ”size“, ”res“,
”time“, ”pri“, ”threads“,
“total“, ”read“, ”write“,
”fault“, ”vcsw“, ”ivcsw“,
“jid“, ”swap“ or ”pid“.
- Show only the process pid.
- Show only those processes owned by jail.
This may be either the jid or
name of the jail. Use 0 to limit to host
processes. Using this option implies
- Show only those processes owned by
username. This option currently only
accepts usernames and will not understand uid numbers.
fields can be specified as
“infinite”, indicating that they can stretch as far as possible.
This is accomplished by using any proper prefix of the keywords
“infinity”, “maximum”, or “all”.
Boolean flags are toggles. A second specification of any of these options will
negate the first.
is running in “interactive
mode”, it reads commands from the terminal and acts upon them
accordingly. In this mode, the terminal is put in “CBREAK”, so
that a character will be processed as soon as it is typed. Almost always, a
key will be pressed when
displays; that is, while it is waiting for
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
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
are recognized, and a newline terminates the input.
These commands are currently recognized (^L refers to control-L):
- Redraw the screen.
- Display a summary of the commands (help screen). Version information is
included in this display.
- Change the number of displays to show (prompt for new number). Remember
that the next display counts as one, so typing
- will make
top show one final display
and then immediately exit.
- Toggle the display between 'cpu' and 'io' modes.
- n or #
- Change the number of processes to display (prompt for new number).
- Change the number of seconds to delay between displays (prompt for new
- Toggle the display of system processes.
- Toggle the display of process titles.
- Send a signal (“kill” by default) to a list of processes.
This acts similarly to the command
- Change the priority (the “nice”) of a list of processes.
This acts similarly to
- Display only processes owned by a specific set of usernames (prompt for
username). If the username specified is simply “+” or
“-”, then processes belonging to all users will be
displayed. Usernames can be added to and removed from the set by
prepending them with “+” and “-”,
- Change the order in which the display is sorted. The sort key names
include “cpu”, “res”, “size”,
“time”. The default is cpu.
- Display a specific process (prompt for pid). If the pid specified is
simply “+”, then show all processes.
- Display a list of system errors (if any) generated by the last
- B H
- Toggle the display of threads.
- i or I
- Toggle the display of idle processes.
- Toggle the display of
- Display only processes owned by a specific jail (prompt for jail). If the
jail specified is simply “+”, then processes belonging to
all jails and the host will be displayed. This will also enable the
display of JID.
- Toggle the display of per-CPU statistics.
- Toggle display of TID and PID
- Toggle the display of the
- Toggle the display of swap usage.
- Toggle the display of the system idle process.
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.
The remainder of the screen displays information about individual processes.
This display is similar in spirit to
but it is not exactly the same. PID is the process id, JID, when displayed, is
ID corresponding to the process, USERNAME is the name of the process's owner
is specified, a UID column will be
substituted for USERNAME), PRI is the current priority of the process, NICE is
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 “START”, “RUN” (shown as
“CPUn” on SMP systems), “SLEEP”,
“STOP”, “ZOMB”, “WAIT”,
“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
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 “<swapped>”).
If a process is in the “SLEEP” or “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 “*” while
sleep events are not.
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
- number of bytes active
- number of clean bytes inactive
- number of dirty bytes queued for laundering
- number of bytes wired down, including IO-level cached file data pages
- number of bytes used for IO-level disk caching
- number of bytes free
These stats are only displayed when the ARC is in use.
- number of wired bytes used for the ZFS ARC
- number of ARC bytes holding most recently used data
- number of ARC bytes holding most frequently used data
- number of ARC bytes holding in flight data
- number of ARC bytes holding headers
- miscellaneous ARC bytes
- bytes of memory used by ARC caches
- bytes of data stored in ARC caches before compression
- compression ratio of data cached in the ARC
- total available swap usage
- total free swap usage
- swap usage
- bytes paged in from swap devices (last interval)
- bytes paged out to swap devices (last interval)
- Default set of arguments to
William LeFebvre, EECS Department, Northwestern
The command name for swapped processes should be tracked down, but this would
make the program run slower.
things can change while
information for an update. The picture it gives is only a close approximation