Frontswap [PATCH 4/4] (was Transcendent Memory): config files Frontswap config defaults to on as the hooks devolve to pointer-compare-to-NULL if no frontswap backend is provided. Signed-off-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> Diffstat: Kconfig | 16 ++++++++++++++++ Makefile | 1 + 2 files changed, 17 insertions(+) --- linux-2.6.34-rc5/mm/Makefile 2010-04-19 17:29:56.000000000 -0600 +++ linux-2.6.34-rc5-frontswap/mm/Makefile 2010-04-21 09:17:37.000000000 -0600 @@ -17,6 +17,7 @@ obj-y += init-mm.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 --- linux-2.6.34-rc5/mm/Kconfig 2010-04-19 17:29:56.000000000 -0600 +++ linux-2.6.34-rc5-frontswap/mm/Kconfig 2010-04-21 09:17:37.000000000 -0600 @@ -287,3 +287,19 @@ config NOMMU_INITIAL_TRIM_EXCESS of 1 says that all excess pages should be trimmed. See Documentation/nommu-mmap.txt for more information. + +config FRONTSWAP + bool "Enable frontswap pseudo-RAM driver to cache swap pages" + default y + help + Frontswap is so named because it can be thought of as the opposite of + a "backing" store for a swap device. The storage is assumed to be + a synchronous concurrency-safe page-oriented pseudo-RAM device (such + as Xen's Transcendent Memory, aka "tmem") which is not directly + accessible or addressable by the kernel and is of unknown (and + possibly time-varying) size. When a pseudo-RAM device is available, + a signficant 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. + + If unsure, say Y to enable frontswap. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>