zram: report maximum used memory
Normally, zram user could get maximum memory usage zram consumed
via polling mem_used_total with sysfs in userspace.
But it has a critical problem because user can miss peak memory
usage during update inverval of polling. For avoiding that,
user should poll it with shorter interval(ie, 0.0000000001s)
with mlocking to avoid page fault delay when memory pressure
is heavy. It would be troublesome.
This patch adds new knob "mem_used_max" so user could see
the maximum memory usage easily via reading the knob and reset
it via "echo 0 > /sys/block/zram0/mem_used_max".
Reviewed-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
4 files changed
