[4/6] Documentation: document zram pool_page_order attribute
Commit Message
Provide a simple documentation for zram pool_page_order
device attribute.
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
Documentation/admin-guide/blockdev/zram.rst | 31 ++++++++++++++++-----
1 file changed, 24 insertions(+), 7 deletions(-)
@@ -112,7 +112,24 @@ to list all of them using, for instance, /proc/crypto or any other
method. This, however, has an advantage of permitting the usage of
custom crypto compression modules (implementing S/W or H/W compression).
-4) Set Disksize
+4) Set maximum pool page order
+==============================
+
+zsmalloc pages can consist of up to 2^N physical pages. The exact size
+is calculated per each zsmalloc size class during zsmalloc pool creation.
+ZRAM provides pool_page_order device attribute to see or change N.
+
+Examples::
+
+ #show current maximum zsmalloc page order
+ cat /sys/block/zramX/pool_page_order
+ 2
+
+ #set maximum zsmalloc page order
+ echo 3 > /sys/block/zramX/pool_page_order
+
+
+5) Set Disksize
===============
Set disk size by writing the value to sysfs node 'disksize'.
@@ -132,7 +149,7 @@ 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) Set memory limit: Optional
+6) Set memory limit: Optional
=============================
Set memory limit by writing the value to sysfs node 'mem_limit'.
@@ -151,7 +168,7 @@ Examples::
# To disable memory limit
echo 0 > /sys/block/zram0/mem_limit
-6) Activate
+7) Activate
===========
::
@@ -162,7 +179,7 @@ Examples::
mkfs.ext4 /dev/zram1
mount /dev/zram1 /tmp
-7) Add/remove zram devices
+8) Add/remove zram devices
==========================
zram provides a control interface, which enables dynamic (on-demand) device
@@ -182,7 +199,7 @@ execute::
echo X > /sys/class/zram-control/hot_remove
-8) Stats
+9) Stats
========
Per-device statistics are exported as various nodes under /sys/block/zram<id>/
@@ -283,7 +300,7 @@ a single line of text and contains the following stats separated by whitespace:
Unit: 4K bytes
============== =============================================================
-9) Deactivate
+10) Deactivate
=============
::
@@ -291,7 +308,7 @@ a single line of text and contains the following stats separated by whitespace:
swapoff /dev/zram0
umount /dev/zram1
-10) Reset
+11) Reset
=========
Write any positive value to 'reset' sysfs node::