linux_kernel/tools/testing/selftests/zram

zram: Compressed RAM based block devices
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* Introduction

The zram module creates RAM based block devices named /dev/zram
( = 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. Some of the usecases include /tmp storage,
use as swap disks, various caches under /var and maybe many more :)

Statistics for individual zram devices are exported through sysfs nodes at
/sys/block/zram/

Kconfig required:
CONFIG_ZRAM=y
CONFIG_CRYPTO_LZ4=y
CONFIG_ZPOOL=y
CONFIG_ZSMALLOC=y

ZRAM Testcases
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zram_lib.sh: create library with initialization/cleanup functions
zram.sh: For sanity check of CONFIG_ZRAM and to run zram01 and zram02

Two functional tests: zram01 and zram02:
zram01.sh: creates general purpose ram disks with ext4 filesystems
zram02.sh: creates block device for swap

Commands required for testing:
- bc
- dd
- free
- awk
- mkswap
- swapon
- swapoff
- mkfs/ mkfs.ext4

For more information please refer:
kernel-source-tree/Documentation/blockdev/zram.txt