zram: record accessed second
authorMinchan Kim <minchan@kernel.org>
Fri, 8 Jun 2018 00:05:45 +0000 (17:05 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 8 Jun 2018 00:34:34 +0000 (17:34 -0700)
commitd7eac6b6e1838ef1a1400df4ec55daa34bbc855e
treec909e5c21f836908a88de0fcc8cce881eec5842a
parent89e85bce4b02edb7408aebf69d5d1a6692a05f4f
zram: record accessed second

zRam as swap is useful for small memory device.  However, swap means
those pages on zram are mostly cold pages due to VM's LRU algorithm.
Especially, once init data for application are touched for launching,
they tend to be not accessed any more and finally swapped out.  zRAM can
store such cold pages as compressed form but it's pointless to keep in
memory.  Better idea is app developers free them directly rather than
remaining them on heap.

This patch records last access time of each block of zram so that With
upcoming zram memory tracking, it could help userspace developers to
reduce memory footprint.

Link: http://lkml.kernel.org/r/20180416090946.63057-4-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/block/zram/zram_drv.c
drivers/block/zram/zram_drv.h