[giomasce]

That still requires you to plan how you use the virtual address space, though. You can't just add more memory pages on the back of your vector if you've already started using those virtual memory locations for other stuff. So you have to know in advance how much space your vector might end up using, and carefully avoid placing anything else there. If you're willing to come up with such an estimate, and if your OS is happy to overcommit memory (and I think Linux is, by default at least), then you can just malloc() all that memory in the first place. With overcommitting no physical page will be used to back your virtual memory block until you really use it.

If your system doesn't do overcommitting, then I guess that with some mmap() trickery (using the appropriate flags) you could do more or less the same thing, reserving the virtual address space that you need and then actually backing with memory as you need.