zswap and zram are actually different systems. zram is a compressed ramdisk that acts like a block device and can host any filesystem (including swapfs). zswap

zswap and zram are actually different systems. zram is a compressed ramdisk that acts like a block device and can host any filesystem (including swapfs). zswap (nee compcache), on the other hand, is a region of memory that tries to store pages compressed instead of swapping them out -- basically a last resort before swapping. zswapped pages are not considered swap, so you have to check sysfs to see how much it's getting used. Many default configurations are pretty aggressive, allowing zswap to use up to 20% of physical memory before finally resorting to the system's configured swap space.