zram: add config and doc file for writeback feature

This patch adds document and kconfig for using of writeback feature.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Minchan Kim <[email protected]>
Cc: Juneho Choi <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Minchan Kim 2017-09-06 16:20:10 -07:00 • committed by Linus Torvalds
commit 5a47074f02
3 changed files with 31 additions and 0 deletions

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@ -168,6 +168,7 @@ max_comp_streams RW the number of possible concurrent compress operations
comp_algorithm RW show and change the compression algorithm
compact WO trigger memory compaction
debug_stat RO this file is used for zram debugging purposes
backing_dev RW set up backend storage for zram to write out
User space is advised to use the following files to read the device statistics.
@ -231,5 +232,15 @@ line of text and contains the following stats separated by whitespace:
resets the disksize to zero. You must set the disksize again
before reusing the device.
* Optional Feature
= writeback
With incompressible pages, there is no memory saving with zram.
Instead, with CONFIG_ZRAM_WRITEBACK, zram can write incompressible page
to backing storage rather than keeping it in memory.
User should set up backing device via /sys/block/zramX/backing_dev
before disksize setting.
Nitin Gupta
[email protected]