1 zram: Compressed RAM based block devices 1 zram: Compressed RAM based block devices
2 ---------------------------------------- 2 ----------------------------------------
3 * Introduction 3 * Introduction
4 4
5 The zram module creates RAM based block device 5 The zram module creates RAM based block devices named /dev/zram<id>
6 (<id> = 0, 1, ...). Pages written to these dis 6 (<id> = 0, 1, ...). Pages written to these disks are compressed and stored
7 in memory itself. These disks allow very fast 7 in memory itself. These disks allow very fast I/O and compression provides
8 good amounts of memory savings. Some of the us 8 good amounts of memory savings. Some of the usecases include /tmp storage,
9 use as swap disks, various caches under /var a 9 use as swap disks, various caches under /var and maybe many more :)
10 10
11 Statistics for individual zram devices are exp 11 Statistics for individual zram devices are exported through sysfs nodes at
12 /sys/block/zram<id>/ 12 /sys/block/zram<id>/
13 13
14 Kconfig required: 14 Kconfig required:
15 CONFIG_ZRAM=y 15 CONFIG_ZRAM=y
16 CONFIG_CRYPTO_LZ4=y 16 CONFIG_CRYPTO_LZ4=y
17 CONFIG_ZPOOL=y 17 CONFIG_ZPOOL=y
18 CONFIG_ZSMALLOC=y 18 CONFIG_ZSMALLOC=y
19 19
20 ZRAM Testcases 20 ZRAM Testcases
21 -------------- 21 --------------
22 zram_lib.sh: create library with initializatio 22 zram_lib.sh: create library with initialization/cleanup functions
23 zram.sh: For sanity check of CONFIG_ZRAM and t 23 zram.sh: For sanity check of CONFIG_ZRAM and to run zram01 and zram02
24 24
25 Two functional tests: zram01 and zram02: 25 Two functional tests: zram01 and zram02:
26 zram01.sh: creates general purpose ram disks w 26 zram01.sh: creates general purpose ram disks with ext4 filesystems
27 zram02.sh: creates block device for swap 27 zram02.sh: creates block device for swap
28 28
29 Commands required for testing: 29 Commands required for testing:
30 - bc 30 - bc
31 - dd 31 - dd
32 - free 32 - free
33 - awk 33 - awk
34 - mkswap 34 - mkswap
35 - swapon 35 - swapon
36 - swapoff 36 - swapoff
37 - mkfs/ mkfs.ext4 37 - mkfs/ mkfs.ext4
38 38
39 For more information please refer: 39 For more information please refer:
40 kernel-source-tree/Documentation/admin-guide/b 40 kernel-source-tree/Documentation/admin-guide/blockdev/zram.rst
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