Enable frontswap to cache swap pages if tmem is present

modulename: frontswap.ko

configname: CONFIG_FRONTSWAP

Linux Kernel Configuration
└─>Memory Management options
└─>Enable frontswap to cache swap pages if tmem is present
In linux kernel since version 3.1 (release Date: 2011-10-24)  
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.

source code:
depends
CONFIG_SWAP

is selected by
CONFIG_ZSWAP

is depended by
CONFIG_ZSWAP