From 27c6aec214264992603526d47da9dabddf3521b3 Mon Sep 17 00:00:00 2001 From: Dan Magenheimer Date: Mon, 9 Apr 2012 17:10:34 -0600 Subject: 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 Acked-by: Jan Beulich Acked-by: Seth Jennings Cc: Jeremy Fitzhardinge Cc: Hugh Dickins Cc: Johannes Weiner Cc: Nitin Gupta Cc: Matthew Wilcox Cc: Chris Mason Cc: Rik Riel Cc: Andrew Morton Signed-off-by: Konrad Rzeszutek Wilk --- mm/Kconfig | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'mm/Kconfig') diff --git a/mm/Kconfig b/mm/Kconfig index e338407f122..2613c910935 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. -- cgit v1.2.3-70-g09d2