1# SPDX-License-Identifier: GPL-2.0 2config ZRAM 3 tristate "Compressed RAM block device support" 4 depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO 5 select CRYPTO_LZO 6 help 7 Creates virtual block devices called /dev/zramX (X = 0, 1, ...). 8 Pages written to these disks are compressed and stored in memory 9 itself. These disks allow very fast I/O and compression provides 10 good amounts of memory savings. 11 12 It has several use cases, for example: /tmp storage, use as swap 13 disks and maybe many more. 14 15 See Documentation/admin-guide/blockdev/zram.rst for more information. 16 17config ZRAM_WRITEBACK 18 bool "Write back incompressible or idle page to backing device" 19 depends on ZRAM 20 help 21 With incompressible page, there is no memory saving to keep it 22 in memory. Instead, write it out to backing device. 23 For this feature, admin should set up backing device via 24 /sys/block/zramX/backing_dev. 25 26 With /sys/block/zramX/{idle,writeback}, application could ask 27 idle page's writeback to the backing device to save in memory. 28 29 See Documentation/admin-guide/blockdev/zram.rst for more information. 30 31config ZRAM_MEMORY_TRACKING 32 bool "Track zRam block status" 33 depends on ZRAM && DEBUG_FS 34 help 35 With this feature, admin can track the state of allocated blocks 36 of zRAM. Admin could see the information via 37 /sys/kernel/debug/zram/zramX/block_state. 38 39 See Documentation/admin-guide/blockdev/zram.rst for more information. 40