Linux Foundation releases open source hypervisor Xen 4.3

Remember when the Linux Foundation used to be just about the Linux operating system? That’s no longer the case. Back in April, Citrix announced it was donating its open source Xen hypervisor to the Linux Foundation group. In doing so, Citrix may have given Xen virtualization a new lease on life.

Mike Woster, COO and vice president at the Linux Foundation, said, “Virtualization is important to Linux and the open source community, and the Xen Project is helping companies realize new levels of scalability and efficiency in areas such as cloud computing.”

[ Also on InfoWorld: Virtual network startup launches platform for cloud data centers | CenturyLink acquires AppFog to offer multicloud PaaS | Track the latest trends in virtualization in InfoWorld’s Virtualization Report newsletter. ]

Citrix decided to give up control of the Xen hypervisor to a more vendor-neutral environment much like it did with the company’s recent donation of another project, CloudStack, to the Apache Foundation. With similar reasons in mind, Citrix made this latest move in the hopes of attracting a more diverse set of contributors to the Xen hypervisor code in order to better compete with the likes of VMware vSphere, Microsoft Hyper-V, and the open source KVM virtualization platform.

At the time of the transfer, the Linux Foundation said it would support continued development and maintenance of Xen, and it established the collaborative project aptly called the Xen Project. With the move to the Linux Foundation, companies such as Amazon Web Services, AMD, CA Technologies, Cisco, Google, Intel, Oracle, Samsung, and Verizon all pledged support for the project.

Fast-forward to last week and this group is ready to make good on its promise with a new release of the Xen hypervisor: Xen Version 4.3.

According to the group, Xen 4.3 is the work of just over nine months of development, with 1,362 changesets containing changes to over 136,128 lines of code — made by 90 individuals from 27 different organizations and 25 unaffiliated individual developers. Citrix still contributed the largest percentage of the changeset count at 41 percent, but other companies have stepped up to the plate as well such as Suse Linux picking up 23 percent, Intel providing 6 percnet, and the U.S. National Security Agency doing another 5 percent.

The new release is licensed under GPLv2 and includes a number of new capabilities and improvements, such as the following:

• Performance and scalability enhancements: The new Non-Uniform Memory Access (NUMA) scheduler will provide significant performance improvements on NUMA hardware. Xen 4.3 also boosts physical memory support on hosts from 5TB to 16TB of RAM. A tool stack bottleneck limitation of 300 virtual CPUs was removed, and tests now reach upward of 750 virtual CPUs. With block protocol scalability, users will see an improvement in read/write performance and throughput with more than six guests on a single host.
• Improved QEMU integration: Earlier releases of Xen had been using a fork of the QEMU hardware emulator, but the Xen Project has switched the default QEMU to QEMU-XEN, which is based on the release of the upstream QEMU project. This will make it easier for Linux operating system distributors to integrate Xen into their distros.
• Software-defined networking (SDN) integration: Xen includes a technology preview of the Open vSwitch technology created by Nicira, now part of VMware. The Open vSwitch is an open source virtual switch technology used as a bridging mechanism to replace older virtual interface code that was originally part of Xen. This is expected to be a fully supported feature in the Xen 4.4 release.
• Better power efficiency: Xen now uses the MWAIT extension of all the modern Intel processors that support it, from Sandy Bridge on. This will improve Xen’s power efficiency.

Perhaps the most interesting new feature for Xen 4.3 is the “Technology Preview” or experimental support for ARM-based processor virtualization. This support not only includes the current 32-bit variant, but also the upcoming 64-bit variant that will arrive with the ARMv8 architecture.

George Dunlap, a software engineer with Citrix, stated in a Xen.org blog post that the 32-bit port of Xen currently boots on the ARMv7 Fast Models, which includes the Cortex A15 platform. On this architecture, Dunlap writes, “It can boot dom0, create other virtual machines and it supports all the basic virtual machine lifecycle operations.” Even though hardware for 64-bit ARM systems-on-a-chip (SoC) is not yet available, Dunlap said engineers also have Xen running well in 64-bit mode on ARMv8 Real-time System Models by ARM.

According to the announcement made by the Linux Foundation, developers working on the Xen Project collaborated with Calxeda and many other vendors to make sure Xen would work on ARMv7 and ARMv8 architectures. Servers using ARMv8 are expected to appear later this year and, more important, may show up in larger volumes during 2014. This type of support could be a deciding factor for bringing ARM-based servers into the Web-scale data centers of many of today’s large Xen-based cloud providers like Amazon and Rackspace.

Lars Kurth, community manager for the Xen Project, added, “The ARM server support is an exciting development for the community and we’re excited about the opportunities this will bring to customers.”

It’s unclear if or when VMware vSphere or Microsoft Hyper-V will support the ARM architecture. ARMv8 support in the Xen hypervisor could prove a challenge for VMware and Microsoft as they continue to compete with the free, community-supported alternative server virtualization platform and try to capture more of the growing cloud market share.

For a complete list of updates and enhancements, visit the Xen 4.3 feature list.

This article, “Linux Foundation releases open source hypervisor Xen 4.3,” was originally published at InfoWorld.com. Follow the latest developments in virtualization at InfoWorld.com.