More advanced users like to know what is nailing their CPU, and have some form of hotkey of screen widget nearby to tell them. But sometimes it takes too much effort for the computer to show you this application while it's thrashing away and I've been looking for a nice unobtrusive on-screen "gadget" that gives me all the information I need. After going through hundreds of windows sidebar gadgets, Mac widgets and now Gnome screenlets, I've hit on a winning strategy (for Linux, but the concept remains the same).

I'm using a semi-transparent Output screenlet to display the contents of the following command in Linux, and GeekTool to do the same on OSX:

GNU/Linux: top -b -n1 -s -i | head -n9 | tail -n3 | grep -v " top " | cut -b1-16,42-50,61-80
BSD: top -R -u -i100 -l2 -ncols 3 | grep PID -A5 | tail -n6

People often forget that disk IO is also an important indicator. Sometimes your CPU usage is moderate but your computer is frozen while your disk thrashes away. So I have a second screenlet with the output of (I don't have one for OSX yet):

iotop -n1 -b -o | grep -v "Total DISK READ:" | cut -b1-38,55-80

What does this buy me? Well, with a quick glance I can find out what process is currently killing my CPU or disk. It also includes the PID for quick "kill" or "renice" access (transparent terminals make reading the PID easy). Additionally, in a few weeks, it has given me a far greater understanding of how applications on my computer work and interact with others. For example, Crossover Office (aka wine) makes Xorg flatline a CPU core when it starts a new wineserver (I blame compiz funkiness). I don't actually care about that, what I do care about is I now know how and when to expect delays when starting crossover apps. The end result of this overcomplicated explanation is that the frustration of using a computer has significantly decreased now that I know what to expect.

Also, when I invariable break something, these strings will be here for me to copy paste back into existence.