I want to deploy Linux on user computers in a way state is never preserved between boots (except state saved explicitly by users on external removable devices). System image will be stored on a read-only removable media and possibly network.
All my target computers have SSDs installed. It will be a waste to do not use them, so I am planning to format them as huge swap partitions. Taking advantage of this, because removable media or network is slow compared to SSD disks, I thought it would be a good idea to load (on demand) whole system image on RAM (as
tmpfs root file system) and let it take advantage of memory swapping.
Problem is that I can only find complaints about
tmpfs and swapping performance. What is so bad with it? How can system fail to decide wich pages keep on ram or on swap? Is
tmpfs is treated differently than the rest of the memory? What performance degradation can I expect from this setup?