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authorDan Magenheimer <dan.magenheimer@oracle.com>2012-04-10 03:10:34 +0400
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2012-05-15 19:34:03 +0400
commit27c6aec214264992603526d47da9dabddf3521b3 (patch)
treebd00824e8c8ed78d299945d7af1b9ceb55f5bd28 /mm
parent29f233cfffe7fbc6672938117ce7e4154a2f515f (diff)
downloadlinux-27c6aec214264992603526d47da9dabddf3521b3.tar.xz
mm: frontswap: config and doc files
This patch 4of4 adds configuration and documentation files including a FAQ. [v14: updated docs/FAQ to use zcache and RAMster as examples] [v10: no change] [v9: akpm@linux-foundation.org: sysfs->debugfs; no longer need Doc/ABI file] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v6: rebase to 3.0-rc1] [v5: change config default to n] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'mm')
-rw-r--r--mm/Kconfig17
-rw-r--r--mm/Makefile1
2 files changed, 18 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index e338407f1225..2613c910935a 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -379,3 +379,20 @@ config CLEANCACHE
in a negligible performance hit.
If unsure, say Y to enable cleancache
+
+config FRONTSWAP
+ bool "Enable frontswap to cache swap pages if tmem is present"
+ depends on SWAP
+ default n
+ help
+ Frontswap is so named because it can be thought of as the opposite
+ of a "backing" store for a swap device. The data is stored into
+ "transcendent memory", memory that is not directly accessible or
+ addressable by the kernel and is of unknown and possibly
+ time-varying size. When space in transcendent memory is available,
+ a significant swap I/O reduction may be achieved. When none is
+ available, all frontswap calls are reduced to a single pointer-
+ compare-against-NULL resulting in a negligible performance hit
+ and swap data is stored as normal on the matching swap device.
+
+ If unsure, say Y to enable frontswap.
diff --git a/mm/Makefile b/mm/Makefile
index 50ec00ef2a0e..306742a28266 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_HAVE_MEMBLOCK) += memblock.o
obj-$(CONFIG_BOUNCE) += bounce.o
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o
+obj-$(CONFIG_FRONTSWAP) += frontswap.o
obj-$(CONFIG_HAS_DMA) += dmapool.o
obj-$(CONFIG_HUGETLBFS) += hugetlb.o
obj-$(CONFIG_NUMA) += mempolicy.o