MM Research

Where might the Linux MM be headed in years to come? If you are doing any Linux MM related research, please add a blurb and any links to your work here.

Superpages

Superpages utilise the ability of many processors to use not just a base page size, but multiples of it. In the current kernel we have the HugeTLB system, which is suitable for x86 which has only two possible page sizes; small (4K) or huge (4MB). Other systems, such as IA64 can have many page sizes inbetween, and you can greatly reduce TLB usage by mapping in larger pages.

Gelato@UNSW

Gelato@UNSW are researching superpage for IA64. See

http://www.gelato.unsw.edu.au/IA64wiki/SuperPages

Page Table Abstraction

3/4 Level page tables aren't a great solution for a sparsely populated 64 bit address space. However, internally the kernel is very much tied to the PGD/PMD/PTE structure for page tables (stemming from it's x86 heratige where this is the most sensible solution).

For research into other methods, we would like to be able to abstract the page table implementation from the kernel.

Gelato@UNSW

Gelato@UNSW are looking at methods to abstract the Linux page tables.

http://www.gelato.unsw.edu.au/IA64wiki/PageTableInterface

Alternate Page Tables

Alternate page table implemenations such as a variable radix page table might make for better performing systems.

Gelato@UNSW

Information on the variable radix page table

http://www.gelato.unsw.edu.au/IA64wiki/VariableRadixPageTables