I recently installed a copy of Ubuntu Server 14.04.2 LTS on a cluster. All appears to be working fine, but a large portion (around half) of our total available RAM is being used. I.e., when I run
free I get the following output (the buffers/cache line being the relevant one):
total used free shared buffers cached Mem: 251 215 36 0 2 70 -/+ buffers/cache: 141 110 Swap: 22 0 22
I checked the outputs of both
lsof to get the total memory usage per user, and nobody is using more than 1% of the RAM. I've read that Linux does not immediately free up memory used by exited processes, but is it feasible that it would continue using this much memory? If not, is there anything else that could be taking up all of this memory?