LinuxTag 2009: Resource Management with OpenVZ
OpenVZ project leader Kir Kolyshkin clarified at LinuxTag 2009 that the software also lends itself to Linux resource management.
The facts are clear, Koyshkin said at the outset: every computer has but finite resources such as CPU time, memory, hard disk size and I/O, and network I/O. Administrators are interested in protecting these resources from DoS attacks so that they can continue providing QoS or simple processing.
The Linux kernel already provides resource management tools, said Kolyshkin: disk quotas, nice and renice, the real-time priority queue and limits on CPU time with ulimit -c. Ulimit alone controls 16 different parameters. However, Kolyshkin doesn't find this pallet to be enough. Some limits can't be set and the others are done so at login and can't subsequently be regulated. This is where Kolyshkin brought OpenVZ into the picture. The software allows creating multiple isolated userspace instances, called containers, on a single kernel. Webhosters, for example, could use these containers for their services. From a resource management viewpoint, containers are simply groups of processes.

OpenVZ brings its own resource control mechanisms, called beancounters, that have access to 20 parameters modifiable for process groups at runtime. These groups can be containers, users or applications. For example, the Apache 2 webserver has many processes that could more sensibly combined into application groups. OpenVZ categorizes these user beancounters (UBCs) on its wiki page.
Kolyshkin revealed that further mainline kernel control mechanisms are available through control groups (cgroups) developed over the years by the big iron folks at Bull and SGI. Paul Menage was responsible for bringing cgroups into the Linux kernel for grouping processes for binding memory controllers. Cgroups, however, don't offer as many features as OpenVZ's beancounters, although Kolyshkin wishes for future OpenVZ features such as shared pages accounting, I/O priorities per cgroup and checkpoint/recreate. The latter freezes the state of a group and is used by container or virtualization software such as OpenVZ and Xen for live migration. Further details are in the /usr/src/linux/Documentation/cgroups/* and /controllers/* directories of the kernel source code.
Kolyshkin would love to see the OpenVZ container features integrated into the mainline kernel, but that will "take years." But he's thinking of the future: integration of checkpoint/recreate in the official Linux kernel.
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.

News
-
New Linux Tool for Security Issues
Seal Security is launching a new solution to automate fixing Linux vulnerabilities.
-
Ubuntu 25.04 Coming Soon
Ubuntu 25.04 (Plucky Puffin) has been given an April release date with many notable updates.
-
Gnome Developers Consider Dropping RPM Support
In a move that might shock a lot of users, the Gnome development team has proposed the idea of going straight up Flatpak.
-
openSUSE Tumbleweed Ditches AppArmor for SELinux
If you're an openSUSE Tumbleweed user, you can expect a major change to the distribution.
-
Plasma 6.3 Now Available
Plasma desktop v6.3 has a couple of pretty nifty tricks up its sleeve.
-
LibreOffice 25.2 Has Arrived
If you've been hoping for a release that offers more UI customizations, you're in for a treat.
-
TuxCare Has a Big AlmaLinux 9 Announcement in Store
TuxCare announced it has successfully completed a Security Technical Implementation Guide for AlmaLinux OS 9.
-
First Release Candidate for Linux Kernel 6.14 Now Available
Linus Torvalds has officially released the first release candidate for kernel 6.14 and it includes over 500,000 lines of modified code, making for a small release.
-
System76 Refreshes Meerkat Mini PC
If you're looking for a small form factor PC powered by Linux, System76 has exactly what you need in the Meerkat mini PC.
-
Gnome 48 Alpha Ready for Testing
The latest Gnome desktop alpha is now available with plenty of new features and improvements.