# df /dev/zram0 4.9G 20M 4.6G 1% /var/tmp # echo 1 > /sys/block/zram0/compact # zramctl NAME ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT /dev/zram0 lz4 5G 785.6M 243.3M 256.3M 4 /var/tmp # uname -a Linux gentoo_server 4.14.8-gentoo-r1 #3 SMP Sat Dec 23 15:59:24 CST 2017 x86_64 Intel(R) Atom(TM) CPU 330 @ 1.60GHz GenuineIntel GNU/Linux zram not free allocated memory even if all files are deleted. compact trigger is not work, this problem make zram useless...