I've been noticing that my server has been using swap a quite more often now but I can't seem to figure out why. The munin graph shows that the apps memory usage is about 0.7G out of the 1.5G. The concern I have is the green line (committed memory). What is committed memory? Is it normal that the committed memory is high compared to the other memory stats, such as apps?
I want to know if I can optimize my apps a bit more or do I really need to just get more RAM for the server.
Currently running daemon apps on this one little server:
- Mysql
- Node JS
- Apache
- Nginx
- Jenkins
- Munin
- Memcache
- Postfix
Committed memory is, essentially, all the memory which has been allocated by applications, whether it's used or not. In contrast, the "apps" is memory that is allocated AND used.
See e.g. https://elixir.bootlin.com/linux/latest/source/Documentation/filesystems/proc.rst#L932
FWIW, you're using 85 MB swap, which seems perfectly Ok; most likely the system is just swapping out unused stuff so that it has more space for useful things like the page cache.