From 4fe4746ab694690af9f2ccb80184f5c575917c7f Mon Sep 17 00:00:00 2001 From: Dan Magenheimer Date: Thu, 26 May 2011 10:00:56 -0600 Subject: mm/fs: cleancache documentation 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 --- Documentation/ABI/testing/sysfs-kernel-mm-cleancache | 11 +++++++++++ 1 file changed, 11 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-cleancache (limited to 'Documentation/ABI/testing') diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-cleancache b/Documentation/ABI/testing/sysfs-kernel-mm-cleancache new file mode 100644 index 0000000..662ae64 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-mm-cleancache @@ -0,0 +1,11 @@ +What: /sys/kernel/mm/cleancache/ +Date: April 2011 +Contact: Dan Magenheimer +Description: + /sys/kernel/mm/cleancache/ contains a number of files which + record a count of various cleancache operations + (sum across all filesystems): + succ_gets + failed_gets + puts + flushes -- cgit v1.1