Lines Matching refs:zram
2 zram: Compressed RAM based block devices
8 The zram module creates RAM based block devices named /dev/zram<id>
14 Statistics for individual zram devices are exported through sysfs nodes at
15 /sys/block/zram<id>/
20 There are several ways to configure and manage zram device(-s):
22 a) using zram and zram_control sysfs attributes
25 In this document we will describe only 'manual' zram configuration steps,
26 IOW, zram and zram_control sysfs attributes.
30 that zram maintainers do not develop/maintain util-linux or zramctl, should
33 Following shows a typical sequence of steps for using zram.
41 zram sysfs attributes always return negative values in case of errors.
47 -ENOMEM zram was not able to allocate enough memory to fulfil your
67 modprobe zram num_devices=4
68 This creates 4 devices: /dev/zram{0,1,2,3}
70 num_devices parameter is optional and tells zram how many devices should be
130 There is little point creating a zram of greater than twice the size of memory
131 since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the
132 size of the disk when not in use so a huge zram is wasteful.
164 7) Add/remove zram devices
167 zram provides a control interface, which enables dynamic (on-demand) device
172 can use /dev/zram<id>) or error code.
176 cat /sys/class/zram-control/hot_add
182 echo X > /sys/class/zram-control/hot_remove
187 Per-device statistics are exported as various nodes under /sys/block/zram<id>/
190 read Documentation/ABI/testing/sysfs-block-zram.
201 writeback_limit WO specifies the maximum amount of write IO zram
208 debug_stat RO this file is used for zram debugging purposes
209 backing_dev RW set up backend storage for zram to write out
216 File /sys/block/zram<id>/stat
221 File /sys/block/zram<id>/io_stat
224 layer and, thus, not available in zram<id>/stat file. It consists of a
246 File /sys/block/zram<id>/mm_stat
264 mem_used_max the maximum amount of memory zram have consumed to
272 File /sys/block/zram<id>/bd_stat
312 With CONFIG_ZRAM_WRITEBACK, zram can write idle/incompressible page
323 To use idle page writeback, first, user need to declare zram pages
328 From now on, any pages on zram are idle pages. The idle mark
336 With the command, zram writeback idle pages from memory to the storage.
342 To overcome the concern, zram supports "writeback_limit" feature.
349 Once writeback_limit_enable is set, zram doesn't allow any writeback
378 The writeback_limit count will reset whenever you reset zram(e.g.,
380 writeback happened until you reset the zram to allocate extra writeback
390 zram block. It could be useful to catch cold or incompressible
394 /sys/kernel/debug/zram/zram0/block_state". The output is as follows::
401 zram's block index.