Recently I appended zcache to my grub configuration:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash zcache"

But I am at a loss as to whether zcache is working or if I need to do something else. There is a severe lack of information on zcache implementation in Ubuntu and most of what there is, is over three to five years old.

It appears that at some point in the past, cleancache and frontswap "modules" were required for zcache to function, but I suspect that this is no longer the case.

So, other than adding zcache to my command line, is there anything else needed to be done, and how can I verify that zcache is fully functioning in my system?

Kernel      : Linux 3.13.0-45-generic (i686)
Compiled        : #74-Ubuntu SMP Tue Jan 13 19:37:48 UTC 2015
Distribution        : Ubuntu 14.04.2 LTS

1 Answer 1


As best as I can tell, zcache was removed from the kernel as of version 3.11:

I would recommend looking at zswap instead. It's enabled just as easily:

  1. Edit /etc/default/grub

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash zswap.enabled=1"
  2. sudo update-grub

  3. Reboot

To verify it's enabled:

dmesg | grep zswap

And to check to see if it's done anything (it will only kick in once your system starts swapping):

sudo sh -c 'cd /sys/kernel/debug/zswap && grep . *'

For more information about zswap:
zram vs zswap vs zcache Ultimate guide: when to use which one

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .