-TODO list
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-
-- Page migration requires the use of swap handles to preserve the
- information of the anonymous page table entries. This means that swap
- space is reserved but never used. The maximum number of swap handles used
- is determined by CHUNK_SIZE (see mm/mempolicy.c) per ongoing migration.
- Reservation of pages could be avoided by having a special type of swap
- handle that does not require swap space and that would only track the page
- references. Something like that was proposed by Marcelo Tosatti in the
- past (search for migration cache on lkml or linux-mm@kvack.org).
-
-- Page migration unmaps ptes for file backed pages and requires page
- faults to reestablish these ptes. This could be optimized by somehow
- recording the references before migration and then reestablish them later.
- However, there are several locking challenges that have to be overcome
- before this is possible.
-
-- Page migration generates read ptes for anonymous pages. Dirty page
- faults are required to make the pages writable again. It may be possible
- to generate a pte marked dirty if it is known that the page is dirty and
- that this process has the only reference to that page.
-
-Christoph Lameter, March 8, 2006.