| Linux appears to be using a great deal of RAM memory. On the 32GB system I am writing this from, top shows that 12.6 GB is being used when there is nothing except for the desktop manager running.
Is Linux really using that much memory?
Yes and no - explanation is below.
Yes, Linux is using 12GB of memory but most of it is for disk caching and application optimization. If an application actually needs the memory, it will free it up for the app.
If you type free -m in a terminal, it will show you three rows called Mem; -/+ buffers/cache; and Swap.
You want to look at the second row, buffers/cache. It shows that 31 of the 32GB are free for applications and that 1.1GB is used by the system.
When should I worry about having too little memory?
One indicator is if the system is using memory in the third row, Swap. That means that it is using your hard drive as RAM memory which is very slow.