Lines Matching refs:zram
1 zram: Compressed RAM based block devices
6 The zram module creates RAM based block devices named /dev/zram<id>
12 Statistics for individual zram devices are exported through sysfs nodes at
13 /sys/block/zram<id>/
17 There are several ways to configure and manage zram device(-s):
18 a) using zram and zram_control sysfs attributes
21 In this document we will describe only 'manual' zram configuration steps,
22 IOW, zram and zram_control sysfs attributes.
26 that zram maintainers do not develop/maintain util-linux or zramctl, should
29 Following shows a typical sequence of steps for using zram.
36 zram sysfs attributes always return negative values in case of errors.
40 -ENOMEM -- zram was not able to allocate enough memory to fulfil your
55 modprobe zram num_devices=4
56 This creates 4 devices: /dev/zram{0,1,2,3}
58 num_devices parameter is optional and tells zram how many devices should be
109 There is little point creating a zram of greater than twice the size of memory
110 since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the
111 size of the disk when not in use so a huge zram is wasteful.
136 7) Add/remove zram devices
138 zram provides a control interface, which enables dynamic (on-demand) device
143 can use /dev/zram<id>) or error code.
146 cat /sys/class/zram-control/hot_add
151 echo X > /sys/class/zram-control/hot_remove
154 Per-device statistics are exported as various nodes under /sys/block/zram<id>/
157 read Documentation/ABI/testing/sysfs-block-zram.
170 debug_stat RO this file is used for zram debugging purposes
171 backing_dev RW set up backend storage for zram to write out
176 File /sys/block/zram<id>/stat
181 File /sys/block/zram<id>/io_stat
184 layer and, thus, not available in zram<id>/stat file. It consists of a
200 File /sys/block/zram<id>/mm_stat
216 mem_used_max the maximum amount of memory zram have consumed to
240 With incompressible pages, there is no memory saving with zram.
241 Instead, with CONFIG_ZRAM_WRITEBACK, zram can write incompressible page
249 zram block. It could be useful to catch cold or incompressible
252 /sys/kernel/debug/zram/zram0/block_state". The output is as follows,
258 First column is zram's block index.