TOP(1) TOP(1) NAME top - display and update information about the top cpu processes SYNOPSIS top [ -SbiInqTuK ] [ -dcount ] [ -stime ] [ -ofield ] [ -Uusername ] [ -Jjob_id ] [ -kcpuset ] [ number ] DESCRIPTION Top 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 number is given, then the top number processes will be displayed instead of the default. Top 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 top is redirected to a file, it acts as if it were being run on a dumb terminal. OPTIONS -S Show system processes in the display. The definition of system processes is system dependent (See below). -b 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 terminal. -i 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. -I Do (or do not) display idle processes (toggle). By default, top displays only active (ready to run or running on a processor) processes. -n Use "non-interactive" mode. This is identical to "batch" mode. -q Renice 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 by root. -T List data for individual kernel threads. Normally the information presented is a summation across all threads of the process. This is of use when examining POSIX threaded processes. -u Do not take the time to 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. -dcount Show only count displays, then exit. A display is considered to be one update of the screen. This option allows the user to select the number of displays he wants to see before top automatically exits. For intelligent terminals, no upper limit is set. The default is 1 for "batch" mode and dumb terminals. -stime Set the delay between screen updates to time seconds. The default delay between updates is 4 seconds. -ofield 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. Likely values are "cpu", "size", "res", and "time", but may vary on different operating systems. Note that not all operating systems support this option. -Uusername Show only those processes owned by username. This option currently only accepts usernames and will not understand uid numbers. -Jjob_id Show only those processes that belong to the job identified by job_id. -K Display which cpusets processes belong to. Processes not attached to a cpuset will be indicated with "?". This option is incompatable with the -TT option. -kcpuset This option accepts the name of a cpuset and will only display processes running on that cpuset. The top lines of the display will still show system wide information. Both count and number 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". The default for count on an intelligent terminal is, in fact, infinity. The environment variable TOP is examined for options before the command line is scanned. This enables a user to set his or her own defaults. The number of processes to display can also be specified in the environment variable TOP. The options -I, -S, and -u are actually toggles. A second specification of any of these options will negate the first. Thus a user who has the environment variable TOP set to "-I" may use the command "top -I" to see only active processes. INTERACTIVE MODE When top 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 top is between displays; that is, while it is waiting for 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 top 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 stty) are recognized, and a newline terminates the input. These commands are currently recognized (^L refers to control-L): ^L Redraw the screen. h or ? Display a summary of the commands (help screen). q Quit top. 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 top show one final display and then immediately exit. n or # Change the number of processes to display (prompt for new number). s Change the number of seconds to delay between displays (prompt for new number). k Send a signal ("kill" by default) to a list of processes. This acts similarly to the command kill(1)). r Change the priority (the "nice") of a list of processes. This acts similarly to the command renice(8)). u Display only processes owned by a specific username (prompt for username). If the username specified is simply "+", then processes belonging to all users will be displayed. e Display a list of system errors (if any) generated by the last kill or renice command. i (or I) Toggle the display of idle processes. T Toggle the display of individual kernel threads within processes. K Display processes belonging to a cpuset (prompt for cpuset). If a value of * is entered, all cpusets will be shown. BATCH MODE In "batch" 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 terminal. By default in "batch" mode, only one screen is displayed before top automatically exits. It should be noted that much of the information displayed by top is based on calculations across the interval between the previous screen and the current screen. If only one screen is displayed, as is the the default for "batch" mode, then there is no previous screen to use as a base, so some of the information will not be available on the first screen. For example, it will only display information on processes that are currently running, and some of the percentages may be zero. To get more useful information using "batch" mode, it is recommended that more than one screen be requested. For example, the command "top -b -d2" will display two screens of information. The second screen will contain more useful information than the first. THE DISPLAY The actual display varies depending on the specific variant of Unix that the machine is running. This description may not exactly match what is seen by top running on this particular machine. Differences are listed at the end of this manual entry. 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 (executing in user mode, executing in kernel mode, idle, etc). 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 ps(1) but it is not exactly the same. PID is the process id, PGRP is the process group id, USERNAME is the name of the process's owner (if -u is specified, a UID column will be substituted for USERNAME), PRI is the current priority of the process, SIZE is the total size of the process (text, data, and stack), RES is the current amount of resident memory (both SIZE and RES are given in kilobytes), STATE is the current state (one of "sleep", "WAIT", "run", "idl", "zomb", or "stop"), 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 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 "<swapped>"). NOTES The "ABANDONED" state (known in the kernel as "SWAIT") was abandoned, thus the name. A process should never end up in this state. AUTHOR William LeFebvre, EECS Department, Northwestern University ENVIRONMENT TOP user-configurable defaults for options. FILES /dev/kmem kernel memory /dev/mem physical memory /etc/passwd used to map uid numbers to user names /vmunix system image BUGS The default for -I is "do not show idle processes". This may be confusing if you're expecting top to display a screenful of processes by default. To appease folks who can't stand that behavior, I have added the ability to set "default" options in the environment variable TOP (see the OPTIONS section). Those who want idle processes displayed need only set the environment variable TOP to "-I". The command name for swapped processes should be tracked down, but this would make the program run slower. As with ps(1), things can change while top is collecting information for an update. The picture it gives is only a close approximation to reality. SEE ALSO kill(1), ps(1), stty(1), mem(4), renice(8) SGI/IRIX NOTES Multiprocessor support was added. Both number of CPUs and the CPU-ID for running processes are shown. On MP systems the sum of %CPU (or %WCPU) numbers may be higher than 100% (one full CPU utilization) but never higher than 100 * the number of CPUs. The IRIX implementation doesn't nlist(2) the kernel to get addresses of symbols which makes it less system dependent. All values are retrieved using the sysmp(2), syssgi(2), and proc(4) interfaces. The same executable should run on any SGI hardware (Uniprocessor, SMP, and S2MP) running IRIX 6.2 and up. "last pid" is not supported. A process is considered to be a "system" process if it has uid=0 and ppid=1. This is a compromise for the sake of backward compatibility. In new IRIX systems many of the traditional "system processes" are implemented either within the kernel as threads, or as real-time processes. System processes display can be toggled interactively using the 'S' key. Idle processes display can be toggled interactively using the 'i' key. Memory sizes are followed by their units: K (Kilobytes), M (Megabytes), G (Gigabytes) or T (Terabytes). The CPU states are sampled every clock tick and provide a "best estimate" of the system CPU activity summed across all processors. On IRIX they are: idle the cpu was idle and not waiting for anything usr the cpu was executing some user mode code ker the cpu was executing some kernel mode code wait the cpu was idle with some i/o outstanding xbrk the cpu was executing code in a fault path intr the cpu was handling an interrupt For example: a high "wait" number means that the system is I/O bound. A close to 100% "usr" number indicates CPU bound processes with little system activity. "xbrk" and "intr" should be close to 0.0% under normal circumstances. Larger numbers may indicate pathologically high low-level driver activity, memory shortage (high VM activity) etc., in which case osview(1) should give a better picture of the system state. The meanings of the idle and wait values changed in the IRIX 6.5.13 release. For details, see the sar(1) man page. The PRI (priority) field supports advanced IRIX real-time and scheduling schemes using the following formats where <pri> is a decimal priority number: +<pri> Real-Time <pri> Normal (timeshared) g<pri> Gang scheduled bc Batch Critical b Batch w Weightless On pre 6.4 systems the supported formats are: +<pri> Real-Time <pri> Normal (timeshared) b<pri> Batch For more details on new IRIX scheduling and priorities, see npri(1), nice(2), realtime(5), and all the sched_XXX(2) services. %WCPU (weighted CPU) is a decaying average of %CPU over a longer period than just the last sampling period. For short running processes %WCPU should be close to %CPU as the two values only diverge over time. This version of top supports sorting by various fields via the command line -o (order) option or the 'o' interactive option. The aliases 'mem' (equivalent to 'size'), and 'rss' (equivalent to 'res') are accepted for friendliness. In addition, the IRIX version of top understands prefixes of field names, like '-os', instead of '-osize', to be used. In case of prefix ambiguities, the first one to match will be used. Use 'h' (help) to list the supported orders. The old IRIX gr_top is now implemented as a perl script on top of the new top to reduce bloat. In addition to the -Bcolor option to set the background color, you may now control the foreground color with -Fcolor, and the title bar color with -Tcolor. Colors are either RGB values or Xwindow color names, e.g. purple. (See showrgb for legal color names.) SGI specific "See Also" should include: osview(1), npri(1), realtime(5), cpuset(5), and schedctl(2). Several more sophisticated performance tools are optionally provided by SGI notably PCP (the Performance CoPilot). Unlike other top versions, the IRIX version should support thousands of processors and an even larger number of processes. Thus it avoids pre- allocating a maximum size for process data. In case the number of processes grows too far a new initialization of data structures is performed by the program restarting itself. This restarting forgets any interactive settings and may cause a change in the Weighted CPU% averages. This should be an extremely rare occurrence but should be noted here. CREDITS Original porting to SGI/IRIX 5.x was done by Sandeep Cariapa. Later enhancements and further IRIX ports by Larry McVoy, John Schimmel, and Ariel Faigon. Page 7