diff options
Diffstat (limited to 'Documentation/blockdev/zram.txt')
| -rw-r--r-- | Documentation/blockdev/zram.txt | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt index 78db38d02bc9..875b2b56b87f 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.txt @@ -243,5 +243,29 @@ to backing storage rather than keeping it in memory. User should set up backing device via /sys/block/zramX/backing_dev before disksize setting. += memory tracking + +With CONFIG_ZRAM_MEMORY_TRACKING, user can know information of the +zram block. It could be useful to catch cold or incompressible +pages of the process with*pagemap. +If you enable the feature, you could see block state via +/sys/kernel/debug/zram/zram0/block_state". The output is as follows, + + 300 75.033841 .wh + 301 63.806904 s.. + 302 63.806919 ..h + +First column is zram's block index. +Second column is access time since the system was booted +Third column is state of the block. +(s: same page +w: written page to backing store +h: huge page) + +First line of above example says 300th block is accessed at 75.033841sec +and the block's state is huge so it is written back to the backing +storage. It's a debugging feature so anyone shouldn't rely on it to work +properly. + Nitin Gupta ngupta@vflare.org |