3 ms·

Note this is for the virtual address space, not only for actual physical RAM. Having 256TB mmap’ed (to another kind of storage) does not seems totally out of re

• saagarjha 6y ago
  And in fact support for 5-level page tables was recently merged into the Linux kernel because people were coming close to this limit and needed more virtual address space.
• ljhsiung 6y ago
  True, but also note that a 52b mode (i.e. 12 bit tag) is also supported. I can't imagine anyone needing more than 4PB in the next 30 years, and the security gains now is (in my opinion) worth the potential refactoring in 30+ years that would be required.
  • StillBored 6y ago
    The couple year old power9 E980, can take 64T of ram. So there are people who have problems that need lots of addressable memory today. Even so, it wouldn't be that hard to actually build a system that could in theory try and map 4PB of storage via mmap today, its about 1/2 a rack of fairly common equipment. Given there are various companies selling 50T ssd (https://www.anandtech.com/show/11639/viking-ships-uhcsilo-ssds-50-tb-capacity-emlc-sas https://www.anandtech.com/show/11639/viking-ships-uhcsilo-ss...) its probably possible to do it in under 10U.
  • guenthert 6y ago
    Hmmh? A few years ago there were already a few sites with more than a PiB of storage total. I don't know of any which used some virtual memory or single address space scheme to access those, but I wouldn't want to rule it out.