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# SPDX-License-Identifier: GPL-2.0
config ZRAM
tristate "Compressed RAM block device support"
depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
select CRYPTO_LZO
help
Creates virtual block devices called /dev/zramX (X = 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.
It has several use cases, for example: /tmp storage, use as swap
disks and maybe many more.
See Documentation/admin-guide/blockdev/zram.rst for more information.
config ZRAM_WRITEBACK
bool "Write back incompressible or idle page to backing device"
depends on ZRAM
help
With incompressible page, there is no memory saving to keep it
in memory. Instead, write it out to backing device.
For this feature, admin should set up backing device via
/sys/block/zramX/backing_dev.
With /sys/block/zramX/{idle,writeback}, application could ask
idle page's writeback to the backing device to save in memory.
See Documentation/admin-guide/blockdev/zram.rst for more information.
config ZRAM_MEMORY_TRACKING
bool "Track zRam block status"
depends on ZRAM && DEBUG_FS
help
With this feature, admin can track the state of allocated blocks
of zRAM. Admin could see the information via
/sys/kernel/debug/zram/zramX/block_state.
See Documentation/admin-guide/blockdev/zram.rst for more information.