Commit 2b281117 authored Jul 10, 2013 by Seth Jennings Committed by Linus Torvalds Jul 10, 2013

zswap: add to mm/



zswap is a thin backend for frontswap that takes pages that are in the
process of being swapped out and attempts to compress them and store
them in a RAM-based memory pool.  This can result in a significant I/O
reduction on the swap device and, in the case where decompressing from
RAM is faster than reading from the swap device, can also improve
workload performance.

It also has support for evicting swap pages that are currently
compressed in zswap to the swap device on an LRU(ish) basis.  This
functionality makes zswap a true cache in that, once the cache is full,
the oldest pages can be moved out of zswap to the swap device so newer
pages can be compressed and stored in zswap.

This patch adds the zswap driver to mm/

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Jenifer Hopper <jhopper@us.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Joe Perches <joe@perches.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4e2e2770

mm/Kconfig

+20 −0

Original line number	Diff line number	Diff line
		@@ -488,6 +488,26 @@ config ZBUD
		deterministic reclaim properties that make it preferable to a higher
		density approach when reclaim will be used.

		config ZSWAP
		bool "Compressed cache for swap pages (EXPERIMENTAL)"
		depends on FRONTSWAP && CRYPTO=y
		select CRYPTO_LZO
		select ZBUD
		default n
		help
		A lightweight compressed cache for swap pages. It takes
		pages that are in the process of being swapped out and attempts to
		compress them into a dynamically allocated RAM-based memory pool.
		This can result in a significant I/O reduction on swap device and,
		in the case where decompressing from RAM is faster that swap device
		reads, can also improve workload performance.

		This is marked experimental because it is a new feature (as of
		v3.11) that interacts heavily with memory reclaim. While these
		interactions don't cause any known issues on simple memory setups,
		they have not be fully explored on the large set of potential
		configurations and workloads that exist.

		config MEM_SOFT_DIRTY
		bool "Track memory changes"
		depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY

mm/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -32,6 +32,7 @@ obj-$(CONFIG_HAVE_MEMBLOCK) += memblock.o
		obj-$(CONFIG_BOUNCE) += bounce.o
		obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o
		obj-$(CONFIG_FRONTSWAP) += frontswap.o
		obj-$(CONFIG_ZSWAP) += zswap.o
		obj-$(CONFIG_HAS_DMA) += dmapool.o
		obj-$(CONFIG_HUGETLBFS) += hugetlb.o
		obj-$(CONFIG_NUMA) += mempolicy.o

mm/zswap.c

0 → 100644

+943 −0

File added.

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