I recently installed the latest release of Ubuntu (9.10 aka Karmic Koala) and was disappointed to find an ancient version of compcache/ramzswap installed by default. My favourite distro (Fedora) does not even ship compcache. Currently, major part of compcache/ramzswap code is included in mainline (2.6.33) however full support is expected no sooner than kernel 2.6.34. I think it will take quite a long time before 2.6.34 kernel is adopted by various distros. Also, it takes considerable amount of time before additions/fixes to compcache are synced with mainline kernel. I think Ubuntu, Fedora and their various 'spins' can benfit from memory compression and there is no need to wait for these future kernel releases. Providing support for uptodate compcache version is also very easy and non-intrusive. Here what any distro needs to do:
- Apply (small) "swap notify" patch to kernel. This patch is included in '-mm' tree since a long time and is well tested.
- Ship ramzswap kernel module and rzscontrol utility as a spearate package. This package can be updated as soon as new compcache version is available for download. This package can be provided through rpmfusion repository for Fedora and something similar for Ubuntu.