Ok, this one is badly documented. Even the kernel docs are outdated.

Here's how to start using zram on Fedora 16:

<code>

# get rpmfusion: http://rpmfusion.org/Configuration

...

# 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/*

</code>

Have fun with it!

# references

http://code.google.com/p/compcache/

http://mystilleef.blogspot.com/2011/10/enable-zram-in-fedora.html