From 2b2811178e85553405b86e3fe78357b9b95889ce Mon Sep 17 00:00:00 2001 From: Seth Jennings Date: Wed, 10 Jul 2013 16:05:03 -0700 Subject: 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 Acked-by: Rik van Riel Cc: Greg Kroah-Hartman Cc: Nitin Gupta Cc: Minchan Kim Cc: Konrad Rzeszutek Wilk Cc: Dan Magenheimer Cc: Robert Jennings Cc: Jenifer Hopper Cc: Mel Gorman Cc: Johannes Weiner Cc: Larry Woodman Cc: Benjamin Herrenschmidt Cc: Dave Hansen Cc: Joe Perches Cc: Joonsoo Kim Cc: Cody P Schafer Cc: Hugh Dickens Cc: Paul Mackerras Cc: Fengguang Wu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/Kconfig | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'mm/Kconfig') diff --git a/mm/Kconfig b/mm/Kconfig index 45503ed5f3aa..8028dcc6615c 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -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 -- cgit v1.2.3-55-g7522