I can’t find some lightweight dm compression layer. Only one i found is VDO and for some reason it uses a lot of memory to operate (on the order of 500 MiB). Why is that? My idea was to use it on a normal laptop/pc that does not have a lot of memory to waste. Only other alternative is btrfs, but it is already slow by itself (compared to other fs like ext4). Idealy what i would want is something like ext4 on VDO (only compression with VDO, and of course there would be LVM in there), only problem with this is that VDO is heavy on memory.
have you tried zram? it’s super lightweight and built right into the kernel - perfect for systems with limited memory and you can tune the compression algorithm to balance between cpu usage and compression ratio.
As far as i know zram is only for compressing ram, it’s not meant for disk storage and is not block device mapper.