🚀 go-pugleaf

>>1) Several posters have mentioned that there is some unspecified but obvious
>>(to them) major problem with using inverted page tables together with
>>memory mapped files.  I wonder if someone could enlighten us regarding
>>this problem, since apparently it isn't obvious to every system architect :-)
>
>The big problem is with sharing.
>
>The word "inverted" is used, because the table is a map from physical
>addresses to virtual addresses. More precisely, you use an array, and
>use physical page numbers as subscripts. Each table entry tells you
>what virtual page is mapped to there.
>
>SO: only one page can be mapped to there. Unless, of course, the OS
>goes through a fair bit of grief to make the machine work right in
>spite of its design.

Now, let's see.  Physical page addresses map to virtual?  Via a hash
function? What ever happened to hash chaining? :-) Especially if the
TLB miss is handled in software (like on MIPS).

--
Andy Glew, aglew@uiuc.edu