xload is one of the small core programs that come with the X Window System. It is a load monitor that measures the system load average. It reads the /dev/kmem device at a set interval (default: ten seconds) and displays the integer figure as a bar in a scrolling graph. The typical way to use it would be to start it in the .xsession file; e.g.
xclock &
xload &
whateverwm &
exec xterm
or something like that.
xload has a few useful options. You can set colors and the text displayed and so forth, but the most useful option is the update interval. The minimum interval is 1 second, which allows you to watch the system load in near real time. There is also the typical "-geometry x+y+widthxheight" option so you can put it where you want.
'xload' is programmed in C, using Xt and the Athena widget set. The coad1 code is small, but I found it hard to understand because of my inexperience with Xt. (It can be gotten with the X Window System distribution, along with 100 MB of other code.)
Related programs include xclock, xterm, xedit, and things like twm that are all included in the distribution.
The dockapp concept is probably inspired by xload and xclock. I cannot find relevant reading on the net, but many dockapps have a similar function to xload and xclock, and it is only natural to think the concept originally came from the useful simplicity of xclock and xload, and the need to integrate them into the environment. The popularity of clock and load dockapps reinforces the idea.
Links:
- http://www.x.org/ - X.org
1. Yes, I did spell it 'coad' the first time. How the hell?