Wednesday, June 8, 2011

LinuxCon Japan 2011 KVM highlights

I had the opportunity to attended LinuxCon Japan 2011 in Yokohama. The conference ran many interesting talks, with a virtualization mini-summit taking place through the first two days. Here are highlights from the conference and some of the latest KVM-related presentation slides.

KVM Ecosystem

Jes Sorensen from Red Hat presented the KVM Weather Report, a status update and look at recent KVM work. Check out his slides if you want an overview of where KVM is today. The main points that I identify are:
  • KVM performance is excellent and continues to improve.
  • In the future, expect advanced features that round out KVM's strengths.
Jes' presentation ends on a nice note with a weather forecast that reads "Cloudy with a chance of total world domination" :).

Virtualization End User Panel

The end user panel brought together three commerical users of open virtualization software to discuss their deployments and answer questions from the audience. I hope a video of this panel will be made available because it is interesting to understand how virtualization is put to use.

All three users were in the hosting or cloud market. The users were split across KVM, Xen, and KVM on standard and VMware on premium offerings. It is clear that KVM is becoming the hypervisor of choice for hosting due to its low cost and good Linux integration - the Xen user had started several years ago but is now evaluating KVM. My personal experience with USA and UK hosting is that Xen is still widely deployed although KVM is growing quickly.

All three users rely on custom management tools and web interfaces. Although libvirt is being used the management layers above it are seen as an opportunity to differentiate. The current breed of open cloud and virtualization management tools weren't seen as mature or scalable enough. I expect this area of the virtualization stack to solidify with several of the open source efforts consolidating in order to reach critical mass.

Storage and Networking

Jes Sorensen from Red Hat covered the KVM Live Snapshot Support work that will allow disk snapshots to be taken for backup and other purposes without stopping the VM. My own talk gave An Updated Overview of the QEMU Storage Stack and covered other current work in the storage area, as well as explaining the most important storage configuration settings when using QEMU.

Stephen Hemminger from Vyatta presented an overview of Virtual Networking Performance. KVM is looking pretty good relative to other hypervisors, no doubt thanks to all the work that has gone into network performance under KVM. Michael Tsirkin and many others are still optimizing virtio-net and vhost_net to reduce latency, improve throughput, and reduce CPU consumption and I think the results justify virtio and paravirtualized I/O. KVM is able to continue improving network performance by extending its virtio host<->guest interface in order to work more efficiently - something that is impossible when emulating existing real-world hardware.

Other KVM-related talks

Isaku Yamahata from VA Linux gave his Status Update on QEMU PCI Express Support. His goal is PCI device assignment of PCI Express adapters. I think his work is important for QEMU in the long term since eventually hardware emulation needs to be able to present modern devices in order for guest operating systems to function.

Guangrong Xiao from Fujitsu presented KVM Memory Virtualization Progress, which describes how guest memory access works. It covers both hardware MMU virtualization in modern processors as well as the software solution used on older hardware. Kernel Samepage Merging (KSM) and Transparent Hugepages (THP) are also touched upon. This is a good technical overview if you want to understand how memory management virtualization works.

More slides and videos

The full slides and videos for talks should be available within the next few weeks. Here are the links to the LinuxCon Japan 2011 main schedule and virtualization mini-summit schedule.