I could do with some help here.
When I look at atop on my ubuntu 14.04 server, I see that the SWP line is permanently red. I switched swap off and on to clear it but it is still red. It (and the MEM) looks like this:

MEM | tot 3.9G | free 150.7M | cache 780.6M | dirty 0.4M | buff 310.3M | slab 736.4M | | | | |
SWP | tot 1.0G | free 1.0G | | | | | | | vmcom 3.6G | vmlim 2.9G

I have tried to understand what the virtual memory overcommit stuf fis and what this warning means but I am afraid I just don't get it...
Can anyone tell me why this line is red and what I should do about it (if anything) - in simple terms please!

PS I also reduce the swappiness from 100 to 50 as I wondered if too much was being swapped - this is a moderately used web server with a few MySQL databases and some websites running apache2 and nginx...

Many Thanks
theWoosh

I can see either it is so obscure noone else gets it either or it's just too boring...