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zram: cosmetic: cleanup documentation 

zram documentation is a mix of different styles: spaces, tabs, tabs +
spaces, etc.  Clean it up.

Link: http://lkml.kernel.org/r/20160531122017.2878-6-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Sergey Senozhatsky 2016-07-26 15:22:51 -07:00 committed by Linus Torvalds
parent 415403be37
commit 69a30a8d2a
1 changed files with 42 additions and 43 deletions
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85
Documentation/blockdev/zram.txt
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@ -59,23 +59,23 @@ num_devices parameter is optional and tells zram how many devices should be
pre-created. Default: 1.
2) Set max number of compression streams
Regardless the value passed to this attribute, ZRAM will always
allocate multiple compression streams - one per online CPUs - thus
allowing several concurrent compression operations. The number of
allocated compression streams goes down when some of the CPUs
become offline. There is no single-compression-stream mode anymore,
unless you are running a UP system or has only 1 CPU online.
Regardless the value passed to this attribute, ZRAM will always
allocate multiple compression streams - one per online CPUs - thus
allowing several concurrent compression operations. The number of
allocated compression streams goes down when some of the CPUs
become offline. There is no single-compression-stream mode anymore,
unless you are running a UP system or has only 1 CPU online.
To find out how many streams are currently available:
To find out how many streams are currently available:
cat /sys/block/zram0/max_comp_streams
3) Select compression algorithm
Using comp_algorithm device attribute one can see available and
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).
Using comp_algorithm device attribute one can see available and
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).
Examples:
Examples:
#show supported compression algorithms
cat /sys/block/zram0/comp_algorithm
lzo [lz4]
@ -83,28 +83,27 @@ pre-created. Default: 1.
#select lzo compression algorithm
echo lzo > /sys/block/zram0/comp_algorithm
For the time being, the `comp_algorithm' content does not necessarily
show every compression algorithm supported by the kernel. We keep this
list primarily to simplify device configuration and one can configure
a new device with a compression algorithm that is not listed in
`comp_algorithm'. The thing is that, internally, ZRAM uses Crypto API
and, if some of the algorithms were built as modules, it's impossible
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).
For the time being, the `comp_algorithm' content does not necessarily
show every compression algorithm supported by the kernel. We keep this
list primarily to simplify device configuration and one can configure
a new device with a compression algorithm that is not listed in
`comp_algorithm'. The thing is that, internally, ZRAM uses Crypto API
and, if some of the algorithms were built as modules, it's impossible
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
Set disk size by writing the value to sysfs node 'disksize'.
The value can be either in bytes or you can use mem suffixes.
Examples:
# Initialize /dev/zram0 with 50MB disksize
echo $((50*1024*1024)) > /sys/block/zram0/disksize
Set disk size by writing the value to sysfs node 'disksize'.
The value can be either in bytes or you can use mem suffixes.
Examples:
# Initialize /dev/zram0 with 50MB disksize
echo $((50*1024*1024)) > /sys/block/zram0/disksize
# Using mem suffixes
echo 256K > /sys/block/zram0/disksize
echo 512M > /sys/block/zram0/disksize
echo 1G > /sys/block/zram0/disksize
# Using mem suffixes
echo 256K > /sys/block/zram0/disksize
echo 512M > /sys/block/zram0/disksize
echo 1G > /sys/block/zram0/disksize
Note:
There is little point creating a zram of greater than twice the size of memory
@ -112,20 +111,20 @@ 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
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
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
# 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
# To disable memory limit
echo 0 > /sys/block/zram0/mem_limit
6) Activate:
mkswap /dev/zram0