System A simple system monitor by Thomas Leonard Brief ~~~~~ System displays information about your system - what processes are running and the amount of memory they are using, as well as free and used disk space. It can also be useful for quitting crashed applications. The latest version can be downloaded from: http://rox.sourceforge.net Conditions ~~~~~~~~~~ This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Please report any bugs to me, <tal197@users.sourceforge.net>. Instructions ~~~~~~~~~~~~ Click on System in a ROX-Filer window to run it. The first time you do this it will compile itself. You need the GTK+ and libgtop2 libraries, including the header files (-devel packages). If you don't have ROX-Filer, you can do it manually from the shell prompt: $ System/AppRun --compile $ System/AppRun Right-click over a processes to show the menu. The Disk Space Display ~~~~~~~~~~~~~~~~~~~~~~ Each mounted filesystem is listed here. The bar beside each one shows the total space on the partition. The dark part shows how much of the partition is already used; the white part shows free space for users. The light area at the start is free space that is reserved for the superuser. By default, the bars are scaled to show how large each filesystem is. This can make small devices (like floppy disks) hard to see. Uncheck the 'Draw bars to scale' box to fix this. Notes about disk usage: The sizes are actually reported in 'blocks' rather than bytes. System assumes that blocks are 512 bytes. If they aren't then the displayed sizes will be wrong. The Processes Display ~~~~~~~~~~~~~~~~~~~~~ This area shows either all processes running on the machine, or just those which you own (use the 'Show all processes' checkbox to change the setting). The processes are laid out in a tree structure showing the parent/child relationship between processes. The PID is the process's unique ID number. The bar beside each one shows the total memory usage of the process. The light part of the bar shows how much of the total space is shared with other processes; the darker part shows how much of the rest is currently in RAM; and the white shows memory that the process is using but which isn't in RAM (usually this is data that has been swapped out to disk). The small circle after each name shows the process's status: - Red : waiting for something to happen (sleeping) - Green : running / ready to run - Yellow : idle (recently running) - Blue : short uninterruptable wait - Black : zombie (dead) - Grey : stopped or traced Note that System will always show itself as running because it's doing a scan when the stats are collected... The RSS (Resident Set Size) column gives the total size of the coloured part of the bar (ie, shared + used; the total amount of memory used excluding swap). Notes about memory usage: Processes can (and often do) share memory. This shared memory is included in every process's bar (the light part). So, if you add up the lengths of all the bars, you won't get the total memory used. Some processes create multiple copies of themselves - these copies usually share most of their memory too. When memory is tight, the kernel may free pages of a process's memory that were loaded from disk and not modified (because it knows it can get them back again). Therefore, the total size of a process may shrink when memory is low. When the kernel runs out of unmodified pages to forget it will start to copy modified pages to the swap partition. In this case, the white part of the bar will expand, but the total size remains the same. Sometimes the white part of the bar may be very large, especially for processes such as X (which includes the video card's memory in the total). Therefore, System ignores this part when scaling the display. Turn off 'Ignore swap when scaling' if you want to see it all. Sending signals: You can send one of four signals to a process by clicking the right mouse button over it and choosing something from the menu. There are many different signals in the Unix world, but System only provides a way to send four: STOP - The process is paused and can't do anything until you send CONT. CONT - A paused process is resumed. TERM - The process is asked nicely to exit. KILL - The process is killed. If you can't kill a process with KILL then it's probably either stuck in a 'disk wait' (blue status circle; kernel problem; often NFS is to blame) or it's already dead (a zombie). Notes about zombies: When a process exits most of the resources it is using are freed. However, the process is not completely removed from the system until its parent process acknowledges its death (or 'reaps' it, to use the technical term). A process which has exited but not yet been reaped is called a zombie. You can't kill a zombie because a zombie is already dead. To get rid of zombies you need to fix / kill the parent.
