My Linux-running laptop seemed to be a little bit sluggish, so I had a look at the amount of free RAM available – and did a double take:
This is on a 4GB machine with a web browser (6 tabs) open, email client, code::blocks IDE and totem to play some music. How can that devour my entire 4GB?
Answer: It can’t. Or at least it’s not! The Linux kernel is in fact using free RAM as a disk cache to keep your most often used data in memory and thus speed up the system. As soon as that RAM is actually needed for applications, then it’s instantly made available. This is in theory like the Windows Superfetch service (which is the first thing I disable on any Windows machine I’m forced to co-exist with), only the Linux version actually works well without perpetually thrashing the pants off the hard drive.
What’s really happening is this:
For the exact workings, please see the excellent (and indeed excellently named) site “Help! Linux ate my RAM!” – http://www.linuxatemyram.com/.
Bit of a PEBKAC moment, there ;-)