2010-06-01 02:01:26 -06:00
|
|
|
zram: Compressed RAM based block devices
|
|
|
|
----------------------------------------
|
2009-09-21 22:56:54 -06:00
|
|
|
|
|
|
|
* Introduction
|
|
|
|
|
2010-08-09 11:26:55 -06:00
|
|
|
The zram module creates RAM based block devices named /dev/zram<id>
|
|
|
|
(<id> = 0, 1, ...). Pages written to these disks are compressed and stored
|
|
|
|
in memory itself. These disks allow very fast I/O and compression provides
|
|
|
|
good amounts of memory savings. Some of the usecases include /tmp storage,
|
|
|
|
use as swap disks, various caches under /var and maybe many more :)
|
2009-09-21 22:56:54 -06:00
|
|
|
|
2010-08-09 11:26:55 -06:00
|
|
|
Statistics for individual zram devices are exported through sysfs nodes at
|
|
|
|
/sys/block/zram<id>/
|
2009-09-21 22:56:54 -06:00
|
|
|
|
|
|
|
* Usage
|
|
|
|
|
2015-09-24 03:56:41 -06:00
|
|
|
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@vger.kernel.org).
|
|
|
|
|
|
|
|
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@vger.kernel.org
|
|
|
|
|
2010-06-01 02:01:26 -06:00
|
|
|
Following shows a typical sequence of steps for using zram.
|
2009-09-21 22:56:54 -06:00
|
|
|
|
2015-09-24 03:56:41 -06:00
|
|
|
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.
|
|
|
|
|
2010-08-09 11:26:55 -06:00
|
|
|
1) Load Module:
|
2010-06-01 02:01:26 -06:00
|
|
|
modprobe zram num_devices=4
|
2010-08-09 11:26:55 -06:00
|
|
|
This creates 4 devices: /dev/zram{0,1,2,3}
|
2015-06-25 16:00:11 -06:00
|
|
|
|
|
|
|
num_devices parameter is optional and tells zram how many devices should be
|
|
|
|
pre-created. Default: 1.
|
2009-09-21 22:56:54 -06:00
|
|
|
|
zram: add multi stream functionality
Existing zram (zcomp) implementation has only one compression stream
(buffer and algorithm private part), so in order to prevent data
corruption only one write (compress operation) can use this compression
stream, forcing all concurrent write operations to wait for stream lock
to be released. This patch changes zcomp to keep a compression streams
list of user-defined size (via sysfs device attr). Each write operation
still exclusively holds compression stream, the difference is that we
can have N write operations (depending on size of streams list)
executing in parallel. See TEST section later in commit message for
performance data.
Introduce struct zcomp_strm_multi and a set of functions to manage
zcomp_strm stream access. zcomp_strm_multi has a list of idle
zcomp_strm structs, spinlock to protect idle list and wait queue, making
it possible to perform parallel compressions.
The following set of functions added:
- zcomp_strm_multi_find()/zcomp_strm_multi_release()
find and release a compression stream, implement required locking
- zcomp_strm_multi_create()/zcomp_strm_multi_destroy()
create and destroy zcomp_strm_multi
zcomp ->strm_find() and ->strm_release() callbacks are set during
initialisation to zcomp_strm_multi_find()/zcomp_strm_multi_release()
correspondingly.
Each time zcomp issues a zcomp_strm_multi_find() call, the following set
of operations performed:
- spin lock strm_lock
- if idle list is not empty, remove zcomp_strm from idle list, spin
unlock and return zcomp stream pointer to caller
- if idle list is empty, current adds itself to wait queue. it will be
awaken by zcomp_strm_multi_release() caller.
zcomp_strm_multi_release():
- spin lock strm_lock
- add zcomp stream to idle list
- spin unlock, wake up sleeper
Minchan Kim reported that spinlock-based locking scheme has demonstrated
a severe perfomance regression for single compression stream case,
comparing to mutex-based (see https://lkml.org/lkml/2014/2/18/16)
base spinlock mutex
==Initial write ==Initial write ==Initial write
records: 5 records: 5 records: 5
avg: 1642424.35 avg: 699610.40 avg: 1655583.71
std: 39890.95(2.43%) std: 232014.19(33.16%) std: 52293.96
max: 1690170.94 max: 1163473.45 max: 1697164.75
min: 1568669.52 min: 573429.88 min: 1553410.23
==Rewrite ==Rewrite ==Rewrite
records: 5 records: 5 records: 5
avg: 1611775.39 avg: 501406.64 avg: 1684419.11
std: 17144.58(1.06%) std: 15354.41(3.06%) std: 18367.42
max: 1641800.95 max: 531356.78 max: 1706445.84
min: 1593515.27 min: 488817.78 min: 1655335.73
When only one compression stream available, mutex with spin on owner
tends to perform much better than frequent wait_event()/wake_up(). This
is why single stream implemented as a special case with mutex locking.
Introduce and document zram device attribute max_comp_streams. This
attr shows and stores current zcomp's max number of zcomp streams
(max_strm). Extend zcomp's zcomp_create() with `max_strm' parameter.
`max_strm' limits the number of zcomp_strm structs in compression
backend's idle list (max_comp_streams).
max_comp_streams used during initialisation as follows:
-- passing to zcomp_create() max_strm equals to 1 will initialise zcomp
using single compression stream zcomp_strm_single (mutex-based locking).
-- passing to zcomp_create() max_strm greater than 1 will initialise zcomp
using multi compression stream zcomp_strm_multi (spinlock-based locking).
default max_comp_streams value is 1, meaning that zram with single stream
will be initialised.
Later patch will introduce configuration knob to change max_comp_streams
on already initialised and used zcomp.
TEST
iozone -t 3 -R -r 16K -s 60M -I +Z
test base 1 strm (mutex) 3 strm (spinlock)
-----------------------------------------------------------------------
Initial write 589286.78 583518.39 718011.05
Rewrite 604837.97 596776.38 1515125.72
Random write 584120.11 595714.58 1388850.25
Pwrite 535731.17 541117.38 739295.27
Fwrite 1418083.88 1478612.72 1484927.06
Usage example:
set max_comp_streams to 4
echo 4 > /sys/block/zram0/max_comp_streams
show current max_comp_streams (default value is 1).
cat /sys/block/zram0/max_comp_streams
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:38:14 -06:00
|
|
|
2) Set max number of compression streams
|
2016-07-26 16:22:51 -06:00
|
|
|
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:
|
zram: add multi stream functionality
Existing zram (zcomp) implementation has only one compression stream
(buffer and algorithm private part), so in order to prevent data
corruption only one write (compress operation) can use this compression
stream, forcing all concurrent write operations to wait for stream lock
to be released. This patch changes zcomp to keep a compression streams
list of user-defined size (via sysfs device attr). Each write operation
still exclusively holds compression stream, the difference is that we
can have N write operations (depending on size of streams list)
executing in parallel. See TEST section later in commit message for
performance data.
Introduce struct zcomp_strm_multi and a set of functions to manage
zcomp_strm stream access. zcomp_strm_multi has a list of idle
zcomp_strm structs, spinlock to protect idle list and wait queue, making
it possible to perform parallel compressions.
The following set of functions added:
- zcomp_strm_multi_find()/zcomp_strm_multi_release()
find and release a compression stream, implement required locking
- zcomp_strm_multi_create()/zcomp_strm_multi_destroy()
create and destroy zcomp_strm_multi
zcomp ->strm_find() and ->strm_release() callbacks are set during
initialisation to zcomp_strm_multi_find()/zcomp_strm_multi_release()
correspondingly.
Each time zcomp issues a zcomp_strm_multi_find() call, the following set
of operations performed:
- spin lock strm_lock
- if idle list is not empty, remove zcomp_strm from idle list, spin
unlock and return zcomp stream pointer to caller
- if idle list is empty, current adds itself to wait queue. it will be
awaken by zcomp_strm_multi_release() caller.
zcomp_strm_multi_release():
- spin lock strm_lock
- add zcomp stream to idle list
- spin unlock, wake up sleeper
Minchan Kim reported that spinlock-based locking scheme has demonstrated
a severe perfomance regression for single compression stream case,
comparing to mutex-based (see https://lkml.org/lkml/2014/2/18/16)
base spinlock mutex
==Initial write ==Initial write ==Initial write
records: 5 records: 5 records: 5
avg: 1642424.35 avg: 699610.40 avg: 1655583.71
std: 39890.95(2.43%) std: 232014.19(33.16%) std: 52293.96
max: 1690170.94 max: 1163473.45 max: 1697164.75
min: 1568669.52 min: 573429.88 min: 1553410.23
==Rewrite ==Rewrite ==Rewrite
records: 5 records: 5 records: 5
avg: 1611775.39 avg: 501406.64 avg: 1684419.11
std: 17144.58(1.06%) std: 15354.41(3.06%) std: 18367.42
max: 1641800.95 max: 531356.78 max: 1706445.84
min: 1593515.27 min: 488817.78 min: 1655335.73
When only one compression stream available, mutex with spin on owner
tends to perform much better than frequent wait_event()/wake_up(). This
is why single stream implemented as a special case with mutex locking.
Introduce and document zram device attribute max_comp_streams. This
attr shows and stores current zcomp's max number of zcomp streams
(max_strm). Extend zcomp's zcomp_create() with `max_strm' parameter.
`max_strm' limits the number of zcomp_strm structs in compression
backend's idle list (max_comp_streams).
max_comp_streams used during initialisation as follows:
-- passing to zcomp_create() max_strm equals to 1 will initialise zcomp
using single compression stream zcomp_strm_single (mutex-based locking).
-- passing to zcomp_create() max_strm greater than 1 will initialise zcomp
using multi compression stream zcomp_strm_multi (spinlock-based locking).
default max_comp_streams value is 1, meaning that zram with single stream
will be initialised.
Later patch will introduce configuration knob to change max_comp_streams
on already initialised and used zcomp.
TEST
iozone -t 3 -R -r 16K -s 60M -I +Z
test base 1 strm (mutex) 3 strm (spinlock)
-----------------------------------------------------------------------
Initial write 589286.78 583518.39 718011.05
Rewrite 604837.97 596776.38 1515125.72
Random write 584120.11 595714.58 1388850.25
Pwrite 535731.17 541117.38 739295.27
Fwrite 1418083.88 1478612.72 1484927.06
Usage example:
set max_comp_streams to 4
echo 4 > /sys/block/zram0/max_comp_streams
show current max_comp_streams (default value is 1).
cat /sys/block/zram0/max_comp_streams
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:38:14 -06:00
|
|
|
cat /sys/block/zram0/max_comp_streams
|
|
|
|
|
2014-04-07 16:38:17 -06:00
|
|
|
3) Select compression algorithm
|
2016-07-26 16:22:51 -06:00
|
|
|
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).
|
2014-04-07 16:38:17 -06:00
|
|
|
|
2016-07-26 16:22:51 -06:00
|
|
|
Examples:
|
2014-04-07 16:38:17 -06:00
|
|
|
#show supported compression algorithms
|
|
|
|
cat /sys/block/zram0/comp_algorithm
|
|
|
|
lzo [lz4]
|
|
|
|
|
|
|
|
#select lzo compression algorithm
|
|
|
|
echo lzo > /sys/block/zram0/comp_algorithm
|
|
|
|
|
2016-07-26 16:22:51 -06:00
|
|
|
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).
|
zram: use crypto api to check alg availability
There is no way to get a string with all the crypto comp algorithms
supported by the crypto comp engine, so we need to maintain our own
backends list. At the same time we additionally need to use
crypto_has_comp() to make sure that the user has requested a compression
algorithm that is recognized by the crypto comp engine. Relying on
/proc/crypto is not an options here, because it does not show
not-yet-inserted compression modules.
Example:
modprobe zram
cat /proc/crypto | grep -i lz4
modprobe lz4
cat /proc/crypto | grep -i lz4
name : lz4
driver : lz4-generic
module : lz4
So the user can't tell exactly if the lz4 is really supported from
/proc/crypto output, unless someone or something has loaded it.
This patch also adds crypto_has_comp() to zcomp_available_show(). We
store all the compression algorithms names in zcomp's `backends' array,
regardless the CONFIG_CRYPTO_FOO configuration, but show only those that
are also supported by crypto engine. This helps user to know the exact
list of compression algorithms that can be used.
Example:
module lz4 is not loaded yet, but is supported by the crypto
engine. /proc/crypto has no information on this module, while
zram's `comp_algorithm' lists it:
cat /proc/crypto | grep -i lz4
cat /sys/block/zram0/comp_algorithm
[lzo] lz4 deflate lz4hc 842
We still use the `backends' array to determine if the requested
compression backend is known to crypto api. This array, however, may not
contain some entries, therefore as the last step we call crypto_has_comp()
function which attempts to insmod the requested compression algorithm to
determine if crypto api supports it. The advantage of this method is that
now we permit the usage of out-of-tree crypto compression modules
(implementing S/W or H/W compression).
[sergey.senozhatsky@gmail.com: zram-use-crypto-api-to-check-alg-availability-v3]
Link: http://lkml.kernel.org/r/20160604024902.11778-4-sergey.senozhatsky@gmail.com
Link: http://lkml.kernel.org/r/20160531122017.2878-5-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>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 16:22:48 -06:00
|
|
|
|
2014-04-07 16:38:17 -06:00
|
|
|
4) Set Disksize
|
2016-07-26 16:22:51 -06:00
|
|
|
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
|
2013-01-29 19:41:40 -07:00
|
|
|
|
2016-07-26 16:22:51 -06:00
|
|
|
# Using mem suffixes
|
|
|
|
echo 256K > /sys/block/zram0/disksize
|
|
|
|
echo 512M > /sys/block/zram0/disksize
|
|
|
|
echo 1G > /sys/block/zram0/disksize
|
2009-09-21 22:56:54 -06:00
|
|
|
|
2014-04-07 16:38:07 -06:00
|
|
|
Note:
|
|
|
|
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.
|
|
|
|
|
2014-10-09 16:29:53 -06:00
|
|
|
5) Set memory limit: Optional
|
2016-07-26 16:22:51 -06:00
|
|
|
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
|
2014-10-09 16:29:53 -06:00
|
|
|
|
|
|
|
6) Activate:
|
2010-06-01 02:01:26 -06:00
|
|
|
mkswap /dev/zram0
|
|
|
|
swapon /dev/zram0
|
|
|
|
|
|
|
|
mkfs.ext4 /dev/zram1
|
|
|
|
mount /dev/zram1 /tmp
|
2009-09-21 22:56:54 -06:00
|
|
|
|
2015-06-25 16:00:24 -06:00
|
|
|
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:
|
2015-04-15 17:16:00 -06:00
|
|
|
Per-device statistics are exported as various nodes under /sys/block/zram<id>/
|
|
|
|
|
2015-09-24 03:56:41 -06:00
|
|
|
A brief description of exported device attributes. For more details please
|
2015-04-15 17:16:00 -06:00
|
|
|
read Documentation/ABI/testing/sysfs-block-zram.
|
|
|
|
|
|
|
|
Name access description
|
|
|
|
---- ------ -----------
|
|
|
|
disksize RW show and set the device's disk size
|
|
|
|
initstate RO shows the initialization state of the device
|
|
|
|
reset WO trigger device reset
|
|
|
|
num_reads RO the number of reads
|
|
|
|
failed_reads RO the number of failed reads
|
|
|
|
num_write RO the number of writes
|
|
|
|
failed_writes RO the number of failed writes
|
|
|
|
invalid_io RO the number of non-page-size-aligned I/O requests
|
|
|
|
max_comp_streams RW the number of possible concurrent compress operations
|
|
|
|
comp_algorithm RW show and change the compression algorithm
|
|
|
|
notify_free RO the number of notifications to free pages (either
|
|
|
|
slot free notifications or REQ_DISCARD requests)
|
|
|
|
zero_pages RO the number of zero filled pages written to this disk
|
|
|
|
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
|
2015-09-24 03:56:41 -06:00
|
|
|
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)
|
2015-04-15 17:16:00 -06:00
|
|
|
mem_limit RW the maximum amount of memory ZRAM can use to store
|
|
|
|
the compressed data
|
2015-09-08 16:04:38 -06:00
|
|
|
pages_compacted RO the number of pages freed during compaction
|
|
|
|
(available only via zram<id>/mm_stat node)
|
2015-06-25 16:00:00 -06:00
|
|
|
compact WO trigger memory compaction
|
2016-05-20 18:00:02 -06:00
|
|
|
debug_stat RO this file is used for zram debugging purposes
|
2015-04-15 17:16:00 -06:00
|
|
|
|
2015-04-15 17:16:09 -06:00
|
|
|
WARNING
|
|
|
|
=======
|
|
|
|
per-stat sysfs attributes are considered to be deprecated.
|
|
|
|
The basic strategy is:
|
|
|
|
-- the existing RW nodes will be downgraded to WO nodes (in linux 4.11)
|
|
|
|
-- deprecated RO sysfs nodes will eventually be removed (in linux 4.11)
|
|
|
|
|
|
|
|
The list of deprecated attributes can be found here:
|
|
|
|
Documentation/ABI/obsolete/sysfs-block-zram
|
|
|
|
|
|
|
|
Basically, every attribute that has its own read accessible sysfs node
|
|
|
|
(e.g. num_reads) *AND* is accessible via one of the stat files (zram<id>/stat
|
|
|
|
or zram<id>/io_stat or zram<id>/mm_stat) is considered to be deprecated.
|
|
|
|
|
|
|
|
User space is advised to use the following files to read the device statistics.
|
|
|
|
|
2015-04-15 17:16:00 -06:00
|
|
|
File /sys/block/zram<id>/stat
|
|
|
|
|
|
|
|
Represents block layer statistics. Read Documentation/block/stat.txt for
|
|
|
|
details.
|
2009-09-21 22:56:54 -06:00
|
|
|
|
2015-04-15 17:16:03 -06:00
|
|
|
File /sys/block/zram<id>/io_stat
|
|
|
|
|
|
|
|
The stat file represents device's I/O statistics not accounted by block
|
|
|
|
layer and, thus, not available in zram<id>/stat file. It consists of a
|
|
|
|
single line of text and contains the following stats separated by
|
|
|
|
whitespace:
|
|
|
|
failed_reads
|
|
|
|
failed_writes
|
|
|
|
invalid_io
|
|
|
|
notify_free
|
|
|
|
|
2015-04-15 17:16:06 -06:00
|
|
|
File /sys/block/zram<id>/mm_stat
|
|
|
|
|
|
|
|
The stat file represents device's mm statistics. It consists of a single
|
|
|
|
line of text and contains the following stats separated by whitespace:
|
|
|
|
orig_data_size
|
|
|
|
compr_data_size
|
|
|
|
mem_used_total
|
|
|
|
mem_limit
|
|
|
|
mem_used_max
|
|
|
|
zero_pages
|
|
|
|
num_migrated
|
|
|
|
|
2015-06-25 16:00:24 -06:00
|
|
|
9) Deactivate:
|
2010-06-01 02:01:26 -06:00
|
|
|
swapoff /dev/zram0
|
|
|
|
umount /dev/zram1
|
2009-09-21 22:56:54 -06:00
|
|
|
|
2015-06-25 16:00:24 -06:00
|
|
|
10) Reset:
|
2010-08-09 11:26:55 -06:00
|
|
|
Write any positive value to 'reset' sysfs node
|
|
|
|
echo 1 > /sys/block/zram0/reset
|
|
|
|
echo 1 > /sys/block/zram1/reset
|
|
|
|
|
2013-01-29 19:41:40 -07:00
|
|
|
This frees all the memory allocated for the given device and
|
|
|
|
resets the disksize to zero. You must set the disksize again
|
|
|
|
before reusing the device.
|
2009-09-21 22:56:54 -06:00
|
|
|
|
|
|
|
Nitin Gupta
|
|
|
|
ngupta@vflare.org
|