Just mentioning in case it helps anyone out: Linux already has a disk buffer cache. If you have available RAM, it will hold on to pages that have been read from disk until there is enough memory pressure to remove them (and then it will only remove some of them, not all of them). If you don't have available RAM, then the tmpfs wouldn't work. The tmpfs is helpful if you know better than the paging subsystem about how much you really want this data to always stay in RAM no matter what, but that is also much less flexible, because sometimes you need to burst in RAM usage.