The patch titled
Subject: zram: update documentation
has been added to the -mm tree. Its filename is
zram-update-documentation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zram-update-documentation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zram-update-documentation.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Sergey SENOZHATSKY <sergey.senozhatsky@xxxxxxxxx>
Subject: zram: update documentation
Several documentation changes.
First, we never mentioned any errors and never required any error checks
in documentation.
Second, mention that there is another way to configure and manage zram
devices -- zramctl, provided by util-linux.
Third, add a bit of clarification on why `mem_used_max' attr is RW and
correct some typos.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/blockdev/zram.txt | 44 +++++++++++++++++++++++++++---
1 file changed, 40 insertions(+), 4 deletions(-)
diff -puN Documentation/blockdev/zram.txt~zram-update-documentation Documentation/blockdev/zram.txt
--- a/Documentation/blockdev/zram.txt~zram-update-documentation
+++ a/Documentation/blockdev/zram.txt
@@ -14,8 +14,43 @@ Statistics for individual zram devices a
* Usage
+There are several ways to configure and manage zram device(-s):
+a) using zram and zram_control sysfs attributes
+b) using zramctl utility, provided by util-linux (util-linux@xxxxxxxxxxxxxxx).
+
+In this document we will describe only 'manual' zram configuration steps,
+IOW, zram and zram_control sysfs attributes.
+
+In order to get a better idea about zramctl please consult util-linux
+documentation, zramctl man-page or `zramctl --help'. Please be informed
+that zram maintainers do not develop/maintain util-linux or zramctl, should
+you have any questions please contact util-linux@xxxxxxxxxxxxxxx
+
Following shows a typical sequence of steps for using zram.
+WARNING
+=======
+For the sake of simplicity we skip error checking parts in most of the
+examples below. However, it is your sole responsibility to handle errors.
+
+zram sysfs attributes always return negative values in case of errors.
+The list of possible return codes:
+-EBUSY -- an attempt to modify an attribute that cannot be changed once
+the device has been initialised. Please reset device first;
+-ENOMEM -- zram was not able to allocate enough memory to fulfil your
+needs;
+-EINVAL -- invalid input has been provided.
+
+If you use 'echo', the returned value that is changed by 'echo' utility,
+and, in general case, something like:
+
+ echo 3 > /sys/block/zram0/max_comp_streams
+ if [ $? -ne 0 ];
+ handle_error
+ fi
+
+should suffice.
+
1) Load Module:
modprobe zram num_devices=4
This creates 4 devices: /dev/zram{0,1,2,3}
@@ -47,7 +82,7 @@ max_comp_streams adjustment.
3) Select compression algorithm
Using comp_algorithm device attribute one can see available and
- currently selected (shown in square brackets) compression algortithms,
+ currently selected (shown in square brackets) compression algorithms,
change selected compression algorithm (once the device is initialised
there is no way to change compression algorithm).
@@ -119,7 +154,7 @@ execute
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
+A brief description of exported device attributes. For more details please
read Documentation/ABI/testing/sysfs-block-zram.
Name access description
@@ -140,8 +175,9 @@ zero_pages RO the number of ze
orig_data_size RO uncompressed size of data stored in this disk
compr_data_size RO compressed size of data stored in this disk
mem_used_total RO the amount of memory allocated for this disk
-mem_used_max RW the maximum amount memory zram have consumed to
- store compressed data
+mem_used_max RW the maximum amount of memory zram have consumed to
+ store the data (to reset this counter to the actual
+ current value, write 1 to this attribute)
mem_limit RW the maximum amount of memory ZRAM can use to store
the compressed data
pages_compacted RO the number of pages freed during compaction
_
Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are
zram-update-documentation.patch
mm-zsmalloc-constify-struct-zs_pool-name.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
