With Docker, which directories are affected by the I / O drive

I want to install TMPFS (ramdrive) before installing dockers so that I can measure the performance benefits.

In my previous tests, it turned out that IOWAIT was slightly higher with Docker, so I uninstalled Docker, installed / var / lib / docker on 3GB ramdisk (TMPFS) and ran my tests again. The results were better, but not much.

Am I missing any other directories that are under intensive disk I / O when working with a Docker container?