Whiteline: Alpha/Whiteline Alpha.iso/dl_serie/013/util/top.doc

Text File | 1994-09-25 | 5.2 KB | 139 lines

NAME
    top - repeatedly display system status

SYNOPSYS
    top [-i] [-s seconds] [-w width] [-n nlines]

DESCRIPTION

"Top" is a program displays a periodically-updated picture of what's going
on in your system.

The display is a snapshot of system activity at periodic intervals. The top
line of the display shows the number of milliseconds included in the
interval, the percentage of that time not accounted for in the running
times of processes listed (idle time), the number of processes, the number
of running processes, and the total number of bytes used (the sum of the
memory sizes of the processes listed).

Below that each process in the system is listed, one per line.
The fields of this line have the following meanings:

    PID    The process ID of this process

    PPID    The process ID of the parent of this process.

    STATUS    The run state of the process: Wait, Sleep, Ready, Exit,
        TSR, and Stop.  The Exit state means this process has
        terminated, but its parent has not received its exit code.
        The Ready state includes the Run state.

    SIZE    The amount of memory allocated to this process.

    TIME    The amount of time this process has run.  This is the sum
        of the user and system times of the process, displayed as
        MM:SS.FF (minutes, seconds, and fraction of a second) or
        HH:MM:SS (hours, minutes, and seconds) if the process has
        run one hour or more.

    %    The percentage of the time in this interval that this
        process accounted for.

    COMMAND    The command this process is running.

The number of processes displayed is limited by the number of lines on
your screen.

OPTIONS

    -s sleep
        Set the interval between updates to 'sleep' seconds.
        Default is 5.

    -w width
        Set the maximum width of a line to 'width'.  The arguments
        in the COMMAND field will be truncated so the line is no
        more than 'width' characters long.  The rest of the display
        (PID, STATUS, etc.) is not affected.  Default is the width
        of your screen.

    -n nlines
        Set the maximum number of processes to display.  This
        defaults to the length of your screen minus three for
        the status, input, and header lines.

    -i    interactive mode

        In Interactive mode the following single-key commands
        can be used:

        s    Prompt for the number of seconds between intervals.

        w    Prompt for the width; the width can be more than the
            screen width, in which case long argument lists will
            take up multiple lines.

        n    Prompt for the maximum number of processes to
            display (nlines). This can be smaller than your
            screen size, but not  larger.

        q    Quit.

        ^L    (control-L) clear and repaint the display.

NOTES

This program uses curses and termcap.  Appropriate environment variables
must be set up.  The screen width and height, and thus the wraparound point
for wide lines and the maximum number of processes to display, are set at
startup time.

The "snapshot of your system" really is a snapshot: if things are moving
too fast, you can get blur.  If a process appears, runs, and exits during a
single interval, top will never see it, and the time it took to run will
appear as "idle" time, because it's not accounted for by the running times
of the processes top did see.  In fact, any time a process exits, its
running time during the last interval appears as idle time.  Also, a
process ("A") can appear in the list along with another process ("B") which
can only have started after "A" exited (e.g. if make is running, a link
process can appear on the same list with an assembler process which
produced the linker's input).  Finally, the sum of the percentages might be
greater than 100.  All this is caused by strobe, roundoff, and nonzero
shutter time effects.

MiNT NOTES

Interactive mode is slower, which is why it isn't the default.  It's slower
because it uses Fselect to sleep while waiting for keyboard input, rather
than using Talarm and Pause, and Fselect sits in a loop with Syield rather
than truly blocking.  MiNT 0.9 is said to fix this.

The Ready state includes the Run state: since top itself is always the
running process when it gets a chance to check, having a separate name for
it conveys no information.

The COMMAND field is the concatenation of the "name" field of the process
and the command-line arguments in the process' basepage.  It can be wildly
inaccurate if the process is using its basepage as its DTA for a directory
search.

Processes are shown in the order they arrived from the directory search. If
there are more processes than lines on your screen (or your nlines value),
you'll see the older, less-interesting ones and lose the newer-more
interesting ones off the bottom.

Top sometimes gets a bus error; this could be a problem related to
operating on processes which don't exist any more.  MiNT might have to keep
a process around if any other process has it open (i.e. has Fopen'ed the
process on drive X:).

AUTHOR

Top for MiNT was written in August, 1991 by Allan Pratt, Atari Corp.
(atari!apratt).  The idea for top came from the program of that name for
BSD UNIX systems. (UNIX is a trademark of AT&T.)  The source code is a
hacked-over version of ps, written in March of 1991 by Tony Reynolds
([e-mail]) and modified by Eric Smith (Mr. MiNT
himself).