27 May, 2011
1 commit
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This patchset introduces cleancache, an optional new feature exposed
by the VFS layer that potentially dramatically increases page cache
effectiveness for many workloads in many environments at a negligible
cost. It does this by providing an interface to transcendent memory,
which is memory/storage that is not otherwise visible to and/or directly
addressable by the kernel.Instead of being discarded, hooks in the reclaim code "put" clean
pages to cleancache. Filesystems that "opt-in" may "get" pages
from cleancache that were previously put, but pages in cleancache are
"ephemeral", meaning they may disappear at any time. And the size
of cleancache is entirely dynamic and unknowable to the kernel.
Filesystems currently supported by this patchset include ext3, ext4,
btrfs, and ocfs2. Other filesystems (especially those built entirely
on VFS) should be easy to add, but should first be thoroughly tested to
ensure coherency.Details and a FAQ are provided in Documentation/vm/cleancache.txt
This first patch of eight in this cleancache series only adds two
new documentation files.[v8: minor documentation changes by author]
[v3: akpm@linux-foundation.org: document sysfs API]
[v3: hch@infradead.org: move detailed description to Documentation/vm]
Signed-off-by: Dan Magenheimer
Reviewed-by: Jeremy Fitzhardinge
Reviewed-by: Konrad Rzeszutek Wilk
Acked-by: Andrew Morton
Acked-by: Randy Dunlap
Cc: Al Viro
Cc: Matthew Wilcox
Cc: Nick Piggin
Cc: Mel Gorman
Cc: Rik Van Riel
Cc: Jan Beulich
Cc: Chris Mason
Cc: Andreas Dilger
Cc: Ted Ts'o
Cc: Mark Fasheh
Cc: Joel Becker
Cc: Nitin Gupta
