Interview: KernelTrap interviews Andrey Savochkin

KernelTrap interviewed Andrey Savochkin, devepment lead of the kernel portion of OpenVZ, the open source subset of SWsoft Virtuozzo, a OS partitioning platform:

KT: Is there any plan to try and get OpenVZ merged into the mainline Linux kernel?

AS: Yes, we’d like to get it merged into the mainstream Linux and are working in that direction. Virtualization makes the next step in the direction of better utilization of hardware and better management, the step that is comparable with the step between single-user and multi-user systems. Virtualization will become more demanded with the growth of hardware capabilities, such as multi-core systems that are currently in the Intel roadmap. So, I believe that when OpenVZ is merged into the mainstream, Linux will instantly become more attractive and more convenient in many usage scenarios. That’s why I think OpenVZ project is so interesting project, and that’s why I’ve invested so much of my time into it.

KT: How large are the changes required in the Linux kernel to support OpenVZ? Can they be broken into small logical pieces?

AS: The current size of the OpenVZ kernel patch is about 2MB (70,000 lines). This size is not small, but it is less than 10% of the average size of the changes between minor versions in 2.6 kernel branch (e.g., 2.6.12 to 2.6.13). OpenVZ patch split into major parts is presented here. OpenVZ code can also be viewed and downloaded from GIT repository at One of the large parts (about 25%) is various stability fixes, which we are submitting to the mainstream. Then comes virtualization itself, general management of resources, CPU scheduler, and so on.

KT: What efforts have been made so far to try and get OpenVZ merged into the kernel?

AS: OpenVZ patch was split into smaller pieces, easier for us to explain and for the community to accept. Then, in the last couple of months, some virtualization pieces have been send to the linux-kernel mailing list and actively discussed there.

The biggest argument was whether we want “partial” virtualization, when VPSs can have, for example, isolated network but common filesystem space. In my personal opinion, in some perfect world such partial virtualization would be ok. But in real life, subsystems of Linux kernel have a lot of dependencies on each other: every subsystem interacts with proc filesystem, for example. Virtualization is cheap, so its easier to to have complete isolation, both from the implementation point of view and then for use and management of VPSs by users.

The process of submitting OpenVZ patches into the mainstream keeps going. Also, we are working with SuSE, RedHat (RHEL and Fedora Core), Xandros, and Mandriva to include OpenVZ in their distributions and make it available and well supported for maximum number of users…

Read the whole interview at source.