Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

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

diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index bef499868269bde3c5dbe1dce96595a4024b2083..c4de576093affed9a5877bfb484c75c67246ab96 100644 (file)
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -19,7 +19,9 @@ Following shows a typical sequence of steps for using zram.
 1) Load Module:
        modprobe zram num_devices=4
        This creates 4 devices: /dev/zram{0,1,2,3}
-       (num_devices parameter is optional. Default: 1)
+
+num_devices parameter is optional and tells zram how many devices should be
+pre-created. Default: 1.
 
 2) Set max number of compression streams
        Compression backend may use up to max_comp_streams compression streams,
@@ -97,7 +99,24 @@ size of the disk when not in use so a huge zram is wasteful.
        mkfs.ext4 /dev/zram1
        mount /dev/zram1 /tmp
 
-7) Stats:
+7) Add/remove zram devices
+
+zram provides a control interface, which enables dynamic (on-demand) device
+addition and removal.
+
+In order to add a new /dev/zramX device, perform read operation on hot_add
+attribute. This will return either new device's device id (meaning that you
+can use /dev/zram<id>) or error code.
+
+Example:
+       cat /sys/class/zram-control/hot_add
+       1
+
+To remove the existing /dev/zramX device (where X is a device id)
+execute
+       echo X > /sys/class/zram-control/hot_remove
+
+8) Stats:
 Per-device statistics are exported as various nodes under /sys/block/zram<id>/
 
 A brief description of exported device attritbutes. For more details please
@@ -172,11 +191,11 @@ line of text and contains the following stats separated by whitespace:
        zero_pages
        num_migrated
 
-8) Deactivate:
+9) Deactivate:
        swapoff /dev/zram0
        umount /dev/zram1
 
-9) Reset:
+10) Reset:
        Write any positive value to 'reset' sysfs node
        echo 1 > /sys/block/zram0/reset
        echo 1 > /sys/block/zram1/reset