tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1# SPDX-License-Identifier: GPL-2.0
2config ZRAM
3 tristate "Compressed RAM block device support"
4 depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
5 depends on CRYPTO_LZO || CRYPTO_ZSTD || CRYPTO_LZ4 || CRYPTO_LZ4HC || CRYPTO_842
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
17choice
18 prompt "Default zram compressor"
19 default ZRAM_DEF_COMP_LZORLE
20 depends on ZRAM
21
22config ZRAM_DEF_COMP_LZORLE
23 bool "lzo-rle"
24 depends on CRYPTO_LZO
25
26config ZRAM_DEF_COMP_ZSTD
27 bool "zstd"
28 depends on CRYPTO_ZSTD
29
30config ZRAM_DEF_COMP_LZ4
31 bool "lz4"
32 depends on CRYPTO_LZ4
33
34config ZRAM_DEF_COMP_LZO
35 bool "lzo"
36 depends on CRYPTO_LZO
37
38config ZRAM_DEF_COMP_LZ4HC
39 bool "lz4hc"
40 depends on CRYPTO_LZ4HC
41
42config ZRAM_DEF_COMP_842
43 bool "842"
44 depends on CRYPTO_842
45
46endchoice
47
48config ZRAM_DEF_COMP
49 string
50 default "lzo-rle" if ZRAM_DEF_COMP_LZORLE
51 default "zstd" if ZRAM_DEF_COMP_ZSTD
52 default "lz4" if ZRAM_DEF_COMP_LZ4
53 default "lzo" if ZRAM_DEF_COMP_LZO
54 default "lz4hc" if ZRAM_DEF_COMP_LZ4HC
55 default "842" if ZRAM_DEF_COMP_842
56
57config ZRAM_WRITEBACK
58 bool "Write back incompressible or idle page to backing device"
59 depends on ZRAM
60 help
61 With incompressible page, there is no memory saving to keep it
62 in memory. Instead, write it out to backing device.
63 For this feature, admin should set up backing device via
64 /sys/block/zramX/backing_dev.
65
66 With /sys/block/zramX/{idle,writeback}, application could ask
67 idle page's writeback to the backing device to save in memory.
68
69 See Documentation/admin-guide/blockdev/zram.rst for more information.
70
71config ZRAM_MEMORY_TRACKING
72 bool "Track zRam block status"
73 depends on ZRAM && DEBUG_FS
74 help
75 With this feature, admin can track the state of allocated blocks
76 of zRAM. Admin could see the information via
77 /sys/kernel/debug/zram/zramX/block_state.
78
79 See Documentation/admin-guide/blockdev/zram.rst for more information.