Ok, this one is badly documented. Even the kernel docs are outdated.
Here’s how to start using zram on Fedora 16:
# get rpmfusion:
...
# install the staging kmod
su -c 'yum install kmod-staging'
# get zram running (aha!)
su -c 'modprobe zram zram_num_devices=4'
# define the block's size (512 MB each)
echo $((512*1024*1024)) > /sys/block/zram0/disksize
echo $((512*1024*1024)) > /sys/block/zram1/disksize
echo $((512*1024*1024)) > /sys/block/zram2/disksize
echo $((512*1024*1024)) > /sys/block/zram3/disksize
# do some swap initialization
mkswap /dev/zram0
swapon /dev/zram0
mkswap /dev/zram1
swapon /dev7zram1
# create a filesystem on the others ( btrfs 
)
mkfs.btrfs /dev/zram[34]
mkdir /mnt/zram
mount /dev/zram3 /mnt/zram
# do some testing!
...
# check out some stats
cat /sys/block/zram3/*
Have fun with it!
# references
http://mystilleef.blogspot.com/2011/10/enable-zram-in-fedora.html