alt Hacker News> exceed swap + a configurable amount (default is 50%) of physical RAM
Naive question: why is this default 50%, and more generally why is this not the entire RAM, what happens to the rest?
Replies
it's a (then-)safe default from the age when having 1GB of RAM and 2GB of swap was the norm: https://linux-kernel.vger.kernel.narkive.com/U64kKQbW/should...
Not sure if I understand your question but nothing "happens to the rest", overcommitting just means processes can allocate memory in excess of RAM + swap. The percentage is arbitrary, could be 50%, 100% or 1000%. Allocating additional memory is not a problem per se, it only becomes a problem when you try to actually write (and subsequently read) more than you have.
Just a guess, but I reckon it doesn't account for things like kernel memory usage, such as caches and buffers. Assigning 100% of physical RAM to applications is probably going to have a Really Bad Outcome.
There's a lot of options. If you want to go down the rabbithole try typing `sysctl -a | grep -E "^vm"` and that'll give you a lot of things to google ;)