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authorVitaly Wool <vitalywool@gmail.com>2016-05-21 01:58:30 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-21 02:58:30 +0200
commit9a001fc19cccdeb9be4c3b89ad089d92df303c44 (patch)
tree7b524d63f6706d29b95a3c4b1cf2d273d1b9a94c /mm/Kconfig
parentmm: thp: split_huge_pmd_address() comment improvement (diff)
downloadlinux-9a001fc19cccdeb9be4c3b89ad089d92df303c44.tar.xz
linux-9a001fc19cccdeb9be4c3b89ad089d92df303c44.zip
z3fold: the 3-fold allocator for compressed pages
This patch introduces z3fold, a special purpose allocator for storing compressed pages. It is designed to store up to three compressed pages per physical page. It is a ZBUD derivative which allows for higher compression ratio keeping the simplicity and determinism of its predecessor. This patch comes as a follow-up to the discussions at the Embedded Linux Conference in San-Diego related to the talk [1]. The outcome of these discussions was that it would be good to have a compressed page allocator as stable and deterministic as zbud with with higher compression ratio. To keep the determinism and simplicity, z3fold, just like zbud, always stores an integral number of compressed pages per page, but it can store up to 3 pages unlike zbud which can store at most 2. Therefore the compression ratio goes to around 2.6x while zbud's one is around 1.7x. The patch is based on the latest linux.git tree. This version has been updated after testing on various simulators (e.g. ARM Versatile Express, MIPS Malta, x86_64/Haswell) and basing on comments from Dan Streetman [3]. [1] https://openiotelc2016.sched.org/event/6DAC/swapping-and-embedded-compression-relieves-the-pressure-vitaly-wool-softprise-consulting-ou [2] https://lkml.org/lkml/2016/4/21/799 [3] https://lkml.org/lkml/2016/5/4/852 Link: http://lkml.kernel.org/r/20160509151753.ec3f9fda3c9898d31ff52a32@gmail.com Signed-off-by: Vitaly Wool <vitalywool@gmail.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/Kconfig')
-rw-r--r--mm/Kconfig12
1 files changed, 11 insertions, 1 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index b0432b71137d..1a6a28ebcb8b 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -567,7 +567,7 @@ config ZPOOL
zsmalloc.
config ZBUD
- tristate "Low density storage for compressed pages"
+ tristate "Low (Up to 2x) density storage for compressed pages"
default n
help
A special purpose allocator for storing compressed pages.
@@ -576,6 +576,16 @@ config ZBUD
deterministic reclaim properties that make it preferable to a higher
density approach when reclaim will be used.
+config Z3FOLD
+ tristate "Up to 3x density storage for compressed pages"
+ depends on ZPOOL
+ default n
+ help
+ A special purpose allocator for storing compressed pages.
+ It is designed to store up to three compressed pages per physical
+ page. It is a ZBUD derivative so the simplicity and determinism are
+ still there.
+
config ZSMALLOC
tristate "Memory allocator for compressed pages"
depends on MMU