Re: [RFC PATCH 3/10] define page_file_cache

Christoph Lameter
2007-11-07T03:26:33Z

n Tue, 6 Nov 2007, Rik van Riel wrote:

> Every anonymous, tmpfs or shared memory segment page is potentially
> swap backed. That is the whole point of the PG_swapbacked flag.

One of the current issues with anonymous pages is the accounting when
they become file backed and get dirty. There are performance issue with
swap writeout because we are not doing it in file order and on a page by
page basis.

Do ramfs pages count as memory backed?

> A page from a filesystem like ext3 or NFS cannot suddenly turn into
> a swap backed page. This page "nature" is not changed during the
> lifetime of a page.

Well COW sortof does that but then its a new page.