> On other hand, large virtual address space would put more pressure on > cache -- at least one more page table per process, if we make 56-bit VA > default.
The top level page always has to be there unless you disable it at boot time (unless you go for a scheme where some processes share top level pages, and others do not, which would likely be very complicated) But even with that it is more than one: A typical set up has at least two extra 4K pages overhead, one for the bottom and one for the top mappings. Could easily be more. -Andi
