Hello, I was trying to test zstd compression for zram devices with kernel 4.15 But to my surprize I found zstd comressor missing from list of compression algos.
I found out this patch or equivalent was still missing in 4.15 and missing in 4.16 as it nearing -rc1: https://lkml.org/lkml/2017/8/4/582 [PATCH v4 5/5] crypto: Add zstd support After manually applying this patch I can see cat /sys/class/block/zram0/comp_algorithm [lzo] lz4 lz4hc 842 zstd and can change algo to zstd If I try and mkfs.ext2 this device (with size, say, ~1Gb) - I can uncompress nearly full kernel tree into it (I first run out of inodes, tons of small files for such small "disk", re-run mkfs with specified number of inodes, around 100 000, worked). But 1Gb device probably was visible size of device, not amount of memory it consumes..So, I run mkfs.btrfs over /dev/zram0 with zstd compression. This give me ~1Gb sized device able to keep full kernel tree, and compile it , too. So, I assume it worked ....
