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
69 This creates 4 devices: /dev/zram{0,1,2,3}
71 num_devices parameter is optional and tells zram how many devices should be
131 There is little point creating a zram of greater than twice the size of memory
132 since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the
133 size of the disk when not in use so a huge zram is wasteful.
165 7) Add/remove zram devices
168 zram provides a control interface, which enables dynamic (on-demand) device
173 can use /dev/zram<id>) or an error code.
177 cat /sys/class/zram-control/hot_add
183 echo X > /sys/class/zram-control/hot_remove
188 Per-device statistics are exported as various nodes under /sys/block/zram<id>/
191 please read Documentation/ABI/testing/sysfs-block-zram.
202 writeback_limit WO specifies the maximum amount of write IO zram
209 debug_stat RO this file is used for zram debugging purposes
210 backing_dev RW set up backend storage for zram to write out
217 File /sys/block/zram<id>/stat
222 File /sys/block/zram<id>/io_stat
225 layer and, thus, not available in zram<id>/stat file. It consists of a
247 File /sys/block/zram<id>/mm_stat
263 mem_used_max the maximum amount of memory zram has consumed to
269 huge_pages_since the number of incompressible pages since zram set up
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
344 With the command, zram will writeback idle pages from memory to the storage.
351 If an admin wants to write a specific page in zram device to the backing device,
360 To overcome the concern, zram supports "writeback_limit" feature.
367 Once writeback_limit_enable is set, zram doesn't allow any writeback
396 The writeback_limit count will reset whenever you reset zram (e.g.,
398 writeback happened until you reset the zram to allocate extra writeback
408 zram block. It could be useful to catch cold or incompressible
412 /sys/kernel/debug/zram/zram0/block_state". The output is as follows::
419 zram's block index.