18c2ecf20Sopenharmony_cizram: Compressed RAM based block devices 28c2ecf20Sopenharmony_ci---------------------------------------- 38c2ecf20Sopenharmony_ci* Introduction 48c2ecf20Sopenharmony_ci 58c2ecf20Sopenharmony_ciThe zram module creates RAM based block devices named /dev/zram<id> 68c2ecf20Sopenharmony_ci(<id> = 0, 1, ...). Pages written to these disks are compressed and stored 78c2ecf20Sopenharmony_ciin memory itself. These disks allow very fast I/O and compression provides 88c2ecf20Sopenharmony_cigood amounts of memory savings. Some of the usecases include /tmp storage, 98c2ecf20Sopenharmony_ciuse as swap disks, various caches under /var and maybe many more :) 108c2ecf20Sopenharmony_ci 118c2ecf20Sopenharmony_ciStatistics for individual zram devices are exported through sysfs nodes at 128c2ecf20Sopenharmony_ci/sys/block/zram<id>/ 138c2ecf20Sopenharmony_ci 148c2ecf20Sopenharmony_ciKconfig required: 158c2ecf20Sopenharmony_ciCONFIG_ZRAM=y 168c2ecf20Sopenharmony_ciCONFIG_CRYPTO_LZ4=y 178c2ecf20Sopenharmony_ciCONFIG_ZPOOL=y 188c2ecf20Sopenharmony_ciCONFIG_ZSMALLOC=y 198c2ecf20Sopenharmony_ci 208c2ecf20Sopenharmony_ciZRAM Testcases 218c2ecf20Sopenharmony_ci-------------- 228c2ecf20Sopenharmony_cizram_lib.sh: create library with initialization/cleanup functions 238c2ecf20Sopenharmony_cizram.sh: For sanity check of CONFIG_ZRAM and to run zram01 and zram02 248c2ecf20Sopenharmony_ci 258c2ecf20Sopenharmony_ciTwo functional tests: zram01 and zram02: 268c2ecf20Sopenharmony_cizram01.sh: creates general purpose ram disks with ext4 filesystems 278c2ecf20Sopenharmony_cizram02.sh: creates block device for swap 288c2ecf20Sopenharmony_ci 298c2ecf20Sopenharmony_ciCommands required for testing: 308c2ecf20Sopenharmony_ci - bc 318c2ecf20Sopenharmony_ci - dd 328c2ecf20Sopenharmony_ci - free 338c2ecf20Sopenharmony_ci - awk 348c2ecf20Sopenharmony_ci - mkswap 358c2ecf20Sopenharmony_ci - swapon 368c2ecf20Sopenharmony_ci - swapoff 378c2ecf20Sopenharmony_ci - mkfs/ mkfs.ext4 388c2ecf20Sopenharmony_ci 398c2ecf20Sopenharmony_ciFor more information please refer: 408c2ecf20Sopenharmony_cikernel-source-tree/Documentation/admin-guide/blockdev/zram.rst 41