Jonathan Blow

So what would you do if you had to page in a 2MB page when there isn't 2MB of contiguous physical memory?

I understand that this is apparently a concern, but I'm not sure I understand why. On modern machines that all have 16+gb of memory, is there some reason the OS can't just sub-divide 4k pages from 2mb pages, and evict all 512 4k pages when deciding to swap in a 2mb page?

That is assuming there are backwards compatibility reasons why you have to keep supporting 4k pages in "compatibility" mode, etc. - I can't honestly see there being a point to 4k pages for the normal case of modern apps that all use literally gigabytes of memory?

Also, paging is kind of for chumps anyway? Like, the OS probably has to support it, but you don’t actually want to be doing it ever, so, probably should not design for that as a primary use case.

Have you got any good ideas on what memory protection without paging might look like, e.g. maybe the ISA lets you specify whole ranges at a time instead of 4k chunks?

He's talking about VM paging, not the concept that there are pages. Jon is just saying that designing your paging system around the case where things page in/out is a bad idea, because that case should never happen in perf-centric scenarios (and I agree).

And, that design made sense back in the 60s-80s when computers were much smaller and you didn't quite expect them to be realtime when doing industrial-scale things. Now we have much more power and would like to use it effectively.