I have 2GB installed on my machine running Ubuntu 12.04. After some time of use, I see much of my RAM used. The RAM does not free enough even though I closed all my programs.
I included 2 screenshots. First is "Gnome system monitor" (all process) and second is "htop" (with sudo), both sorted by memory usage. From both you see, that it's not possible that all running apps takes together 1GB of memory. First 7 biggest programs sum 250, but others are much smaller (all can't sum even 100MB). The cache is 300MB (yellow ||| on htop) and is not included in 1GB used. Also 260MB is already on swap. (which actually makes 1,3GB of used memory)
If i start Firefox (or Chrome) with many tabs, it has only 1GB available and not potentially 1,5 GB (assume 0,5GB is for system). When I need more ram, swapping happens.
So where is my ram? Which program is using it? How can i free it, to be available for e.g. Firefox?
Gnome system monitor htop