Command Center

d: UID -- User Id

The effective user ID of the task's owner.

e: USER -- User Name

The effective user name of the task's owner.

f: GROUP -- Group Name

The effective group name of the task's owner.

g: TTY -- Controlling Tty

The name of the controlling terminal. This is usually the device (serial port, pty, etc.) from which the process was started, and which it uses for input or output. However, a task need not be associated with a terminal, in which case you'll see '?' displayed.

h: PR -- Priority

The priority of the task.

i: NI -- Nice value

The nice value of the task. A negative nice value means higher priority, whereas a positive nice value means lower priority. Zero in this field simply means priority will not be adjusted in determining a task's dispatchability./dd>

j: P -- Last used CPU (SMP)

A number representing the last used processor. In a true SMP environment this will likely change frequently since the kernel intentionally uses weak affinity. Also, the very act of running top may break this weak affinity and cause more processes to change CPUs more often (because of the extra demand for cpu time).

k: %CPU -- CPU usage

The task's share of the elapsed CPU time since the last screen update, expressed as a percentage of total CPU time. In a true SMP environment, if 'Irix mode' is Off, top will operate in 'Solaris mode' where a task's cpu usage will be divided by the total number of CPUs. You toggle 'Irix/Solaris' modes with the 'I' interactive command.

l: TIME -- CPU Time

Total CPU time the task has used since it started. When 'Cumulative mode' is On, each process is listed with the cpu time that it and its dead children has used. You toggle 'Cumulative mode' with 'S', which is a command-line option and an interactive command. See the 'S' interactive command for additional information regarding this mode.

m: TIME+ -- CPU Time, hundredths

The same as 'TIME', but reflecting more granularity through hundredths of a second.

n: %MEM -- Memory usage (RES)

A task's currently used share of available physical memory.

o: VIRT -- Virtual Image (kb)

The total amount of virtual memory used by the task. It includes all code, data and shared libraries plus pages that have been swapped out.

p: SWAP -- Swapped size (kb)

The swapped out portion of a task's total virtual memory image.

q: RES -- Resident size (kb)

The non-swapped physical memory a task has used.

RES = CODE + DATA.

r: CODE -- Code size (kb)

The amount of physical memory devoted to executable code, also known as the 'text resident set' size or TRS.

s: DATA -- Data+Stack size (kb)

The amount of physical memory devoted to other than executable code, also known as the 'data resident set' size or DRS.

t: SHR -- Shared Mem size (kb)

The amount of shared memory used by a task. It simply reflects memory that could be potentially shared with other processes.

u: nFLT -- Page Fault count

The number of major page faults that have occurred for a task. A page fault occurs when a process attempts to read from or write to a virtual page that is not currently present in its address space. A major page fault is when disk access is involved in making that page available.

v: nDRT -- Dirty Pages count

The number of pages that have been modified since they were last written to disk. Dirty pages must be written to disk before the corresponding physical memory location can be used for some other virtual page.

w: S -- Process Status

The status of the task which can be one of:
'D' = uninterruptible sleep
'R' = running
'S' = sleeping
'T' = traced or stopped
'Z' = zombie Tasks shown as running should be more properly thought of as 'ready to run' -- their task_struct is simply represented on the Linux run-queue. Even without a true SMP machine, you may see numerous tasks in this state depending on top's delay interval and nice value.

x: Command -- Command line or Program name

Display the command line used to start a task or the name of the associated program. You toggle between command line and name with 'c', which is both a command-line option and an interactive command. When you've chosen to display command lines, processes without a command line (like kernel threads) will be shown with only the program name in parentheses, as in this example:
( mdrecoveryd )
Either form of display is subject to potential truncation if it's too long to fit in this field's current width. That width depends upon other fields selected, their order and the current screen width.
Note: The 'Command' field/column is unique, in that it is not fixed-width. When displayed, this column will be allocated all remaining screen width (up to the maximum 512 characters) to provide for the potential growth of program names into command lines.

y: WCHAN -- Sleeping in Function

Depending on the availability of the kernel link map ('System.map'), this field will show the name or the address of the kernel function in which the task is currently sleeping. Running tasks will display a dash ('-') in this column. Note: By displaying this field, top's own working set will be
increased by over 700Kb. Your only means of reducing that overhead
will be to stop and restart top.

z: Flags -- Task Flags

This column represents the task's current scheduling flags which are expressed in hexadecimal notation and with zeros suppressed. These flags are officially documented in . Less formal documentation can also be found on the 'Fields select' and 'Order fields' screens.

Interactive commands
While top is running you may issue some options that will interact immediately with top these options are:

h

Help, displays a summary of command that will modify the behavior of top

k

Kills a process, you will be able to kill only your own processes, unless you are running top as root

n

Once this command is entered top will ask you how many lines you want on your screen, if you enter 0 top will display as much as it can

q

Exits top

r

Change the priority of a process, as well as with k you will only be able to act on your own processes unless you are root

W

Writes the current configuration to your personal configuration file, which is $HOME/.toprc

Example
top - 22:29:04 up 7:16, 3 users, load average: 0.06, 0.08, 0.08
Tasks: 105 total, 2 running, 99 sleeping, 0 stopped, 4 zombie
Cpu(s): 2.5%us, 0.7%sy, 0.0%ni, 95.7%id, 1.0%wa, 0.2%hi, 0.0%si, 0.0%st
Mem: 1035196k total, 796652k used, 238544k free, 55680k buffers
Swap: 2650684k total, 0k used, 2650684k free, 432516k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
4267 root 15 0 320m 45m 10m S 4 4.5 4:45.33 X
2865 haldaemo 17 0 5736 4136 1864 S 0 0.4 0:23.18 hald
1 root 15 0 744 288 240 S 0 0.0 0:01.15 init
2 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/0
3 root 34 19 0 0 0 S 0 0.0 0:00.00 ksoftirqd/0
4 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/1
5 root 34 19 0 0 0 S 0 0.0 0:00.00 ksoftirqd/1
6 root 10 -5 0 0 0 S 0 0.0 0:00.12 events/0
7 root 10 -5 0 0 0 S 0 0.0 0:00.00 events/1
8 root 12 -5 0 0 0 S 0 0.0 0:00.00 khelper
9 root 10 -5 0 0 0 S 0 0.0 0:00.00 kthread
13 root 14 -5 0 0 0 S 0 0.0 0:00.00 kblockd/0
14 root 10 -5 0 0 0 S 0 0.0 0:00.00 kblockd/1
15 root 16 -5 0 0 0 S 0 0.0 0:00.00 kacpid
125 root 11 -5 0 0 0 S 0 0.0 0:00.00 cqueue/0
126 root 11 -5 0 0 0 S 0 0.0 0:00.00 cqueue/1
127 root 10 -5 0 0 0 S 0 0.0 0:00.02 kseriod
171 root 16 0 0 0 0 S 0 0.0 0:00.00 pdflush
172 root 15 0 0 0 0 S 0 0.0 0:00.06 pdflush
173 root 12 -5 0 0 0 S 0 0.0 0:00.00 kswapd0
174 root 12 -5 0 0 0 S 0 0.0 0:00.00 aio/0
175 root 13 -5 0 0 0 S 0 0.0 0:00.00 aio/1
435 root 12 -5 0 0 0 S 0 0.0 0:00.00 kpsmoused
847 root 10 -5 0 0 0 S 0 0.0 0:00.00 ata/0