zram: zram memory size limitation

[firefly-linux-kernel-4.4.55.git] / Documentation / blockdev / zram.txt

diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 2db1687a4b10766113bf82f371b22e966d4abc61..4331ebf94bf0e764742c3436b2a883a13e261fe5 100644 (file)
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -74,14 +74,30 @@ There is little point creating a zram of greater than twice the size of memory
 since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the
 size of the disk when not in use so a huge zram is wasteful.
 
-5) Activate:
+5) Set memory limit: Optional
+       Set memory limit by writing the value to sysfs node 'mem_limit'.
+       The value can be either in bytes or you can use mem suffixes.
+       In addition, you could change the value in runtime.
+       Examples:
+           # limit /dev/zram0 with 50MB memory
+           echo $((50*1024*1024)) > /sys/block/zram0/mem_limit
+
+           # Using mem suffixes
+           echo 256K > /sys/block/zram0/mem_limit
+           echo 512M > /sys/block/zram0/mem_limit
+           echo 1G > /sys/block/zram0/mem_limit
+
+           # To disable memory limit
+           echo 0 > /sys/block/zram0/mem_limit
+
+6) Activate:
        mkswap /dev/zram0
        swapon /dev/zram0
 
        mkfs.ext4 /dev/zram1
        mount /dev/zram1 /tmp
 
-6) Stats:
+7) Stats:
        Per-device statistics are exported as various nodes under
        /sys/block/zram<id>/
                disksize
@@ -95,11 +111,11 @@ size of the disk when not in use so a huge zram is wasteful.
                compr_data_size
                mem_used_total
 
-7) Deactivate:
+8) Deactivate:
        swapoff /dev/zram0
        umount /dev/zram1
 
-8) Reset:
+9) Reset:
        Write any positive value to 'reset' sysfs node
        echo 1 > /sys/block/zram0/reset
        echo 1 > /sys/block/zram1/reset