top

NAME

       top - display top CPU processes

SYNOPSIS

       top [-] [d delay] [q] [S] [s] [i] [-V]

DESCRIPTION

       top provides an ongoing look at processor activity in real
       time.  It displays a listing  of  the  most  CPU-intensive
       tasks on the system, and can provide an interactive inter-
       face for manipulating processes.

COMMAND-LINE OPTIONS

       d    Specifies the delay between screen updates.  You  can
            change this with the s interactive command.

       q    This  causes top to refresh without any delay. If the
            caller has superuser priviledges, top runs  with  the
            highest possible priority.

       S    Specifies  cumulative  mode,  where  each  process is
            listed with the CPU time that it as well as its  dead
            children  has  spent.   This  is  like the -S flag to
            ps(1).  See the discussion below of the S interactive
            command.

       s    Tells  top  to run in secure mode.  This disables the
            potentially dangerous  of  the  interactive  commands
            (see  below).  A secure top is a nifty thing to leave
            running on a spare terminal.

       i    Start top ignoring any idle or zombie processes.  See
            the interactive command i below.

       V    Display version information.

FIELD DESCRIPTIONS

       top  displays a variety of information about the processor
       state.  The display is updated every 5 seconds by default,
       but  you can change that with the d command-line option or
       the s interactive command.

       uptime
            This line displays the time the system has  been  up,
            and the three load averages for the system.  The load
            averages are the average number of process  ready  to
            run  during  the last 1, 5 and 15 minutes.  This line
            is just like the output of uptime(1).

       processes
            The total number of processes running at the time  of
            the  last  update.  This is also broken down into the
            number of tasks which are running, sleeping, stopped,
            or undead.

       CPU states
            Shows the percentage of CPU time in user mode, system
            mode, niced tasks, and idle.  (Niced tasks  are  only
            those  whose  nice value is negative.)  Time spent in
            niced tasks will also be counted in system  and  user
            time, so the total will be more than 100%.

       Mem  Statistics on memory usage, including total available
            memory, free memory, used memory, shared memory,  and
            memory used for buffers.

       Swap Statistics on swap space, including total swap space,
            available swap space, and used swap space.  This  and
            Mem are just like the output of free(1).

       PID  The process ID of each task.

       USER The user name of the task's owner.

       PRI  The priority of the task.

       NI   The nice value of the task.  Negative nice values are
            lower priority.

       SIZE The size of the task's  code  plus  data  plus  stack
            space, in kilobytes, is shown here.

       RSS  The total amount of physical memory used by the task,
            in kilobytes, is shown here.

       SHRD The amount of shared memory used by the task is shown
            in this column.

       ST   The  state  of  the  task is shown here. The state is
            either S for sleeping, D for uninterruptible sleep, R
            for  running,  Z  for  zombies,  or  T for stopped or
            traced.

       TIME Total CPU time the task has used  since  it  started.
            If  cumulative mode is on, this also includes the CPU
            time used by the process's children which have  died.
            You  can  set cumulative mode with the S command line
            option or toggle it with the interactive command S.

       %CPU The task's share of  the  CPU  time  since  the  last
            screen update, expressed as a percentage of total CPU
            time.

       %MEM The task's share of the physical memory.

       COMMAND
            The task's command name, which will be  truncated  if
            it is too long to be displayed on one line.  Tasks in
            memory will have a full command line, but swapped-out
            tasks  will  only  have  the  name  of the program in
            parentheses (for example, "(getty)").

INTERACTIVE COMMANDS

       Several single-key commands are recognized  while  top  is
       running.  Some are disabled if the s option has been given
       on the command line.

       ^L   Erases and redraws the screen.

       h or ?
            Displays a help screen giving a brief summary of com-
            mands, and the status of secure and cumulative modes.

       k    Kill a process.  You will be prompted for the PID  of
            the task, and the signal to send to it.  For a normal
            kill, send signal 15.  For a sure, but rather abrupt,
            kill,  send  signal  9.   The default signal, as with
            kill(1), is 15, SIGTERM.  This command is not  avail-
            able in secure mode.

       i    Ignore  idle  and zombie processes.  This is a toggle
            switch.

       n or #
            Change the number of processes to show.  You will  be
            prompted  to  enter the number.  This overrides auto-
            matic determination of the  number  of  processes  to
            show,  which is based on window size measurement.  If
            0 is specified, then top will show as many  processes
            as will fit on the screen; this is the default.

       q    Quit.

       r    Re-nice  a process.  You will be prompted for the PID
            of the task, and the value to nice it to.  Entering a
            positve  value  will  cause  a process to be niced to
            negative values, and lose priority.  If root is  run-
            ning  top, a negative value can be entered, causing a
            process to get a higher than  normal  priority.   The
            default  renice  value  is  10.   This command is not
            available in secure mode.

       S    This toggles cumulative mode, the  equivalent  of  ps
            -S,  i.e.,  that  CPU  times will include a process's
            defunct children.  For some programs, such as compil-
            ers,  which work by forking into many seperate tasks,
            normal mode will make them appear less demanding than
            they  actually  are.   For  others,  however, such as
            shells and init, this behavior is  correct.   In  any
            case,  try cumulative mode for an alternative view of
            CPU use.

       s    Change  the  delay  between  updates.   You  will  be
            prompted to enter the delay time, in seconds, between
            updates.  Fractional values are  recognized  down  to
            microseconds.   Entering 0 causes continuous updates.
            The default value is 5 seconds.  Note that low values
            cause  nearly  unreadably  fast displays, and greatly
            raise the load.  This command  is  not  available  in
            secure mode.

NOTES

       This proc-based top works by reading the files in the proc
       filesystem, mounted on /proc.  If /proc  is  not  mounted,
       top will not work.

       %CPU  shows  the cputime/realtime percentage in the period
       of time between updates.  For the first  update,  a  short
       delay  is  used,  and  top itself dominates the CPU usage.
       After that, top will drop back, and a more reliable  esti-
       mate of CPU usage is available.

       The  SIZE  and  RSS fields don't count the page tables and
       the task_struct of a process; this is at least 12K of mem-
       ory  that is always resident.  SIZE is the virtual size of
       the process (code+data+stack).

       Keep in mind that a process must die for its  time  to  be
       recorded  on  its parent by cumulative mode.  Perhaps more
       useful behavior would be to follow each  process  upwards,
       adding  time,  but  that would be more expensive, possibly
       prohibitively so.  In any  case,  that  would  make  top's
       behavior incompatible with ps.

SEE ALSO

       ps(1), free(1), uptime(1), kill(1), renice(1).

BUGS

       If the window is less than about 70x7, top will not format
       information correctly.

AUTHOR

       top was originally written by Roger Binns, based on Branko
       Lankester's   (lankeste@fwi.uva.nl)  ps  program.   Robert
       Nation  (nation@rocket.sanders.lockheed.com)  re-wrote  it
       significantly to use the proc filesystem, based on Michael
       K Johnson's (johnsonm@sunsite.unc.edu) proc-based ps  pro-
       gram.   Many changes were made, including secure and cumu-
       lative modes and a general  cleanup,  by  Michael  Shields
       (mjshield@nyx.cs.du.edu).