QEMU 4.2 Released With Many Improvements For Linux Virtualization

[sorbus]

VMWare is the long-term incumbent, with VSphere. Anyone who complains about VMWare's performance isn't using it right, or they're just using Player and thinking that alone is indicative of the paid product. Every other virtualisation project is basically playing catch-up with VMWare. Full disclosure, I've been a VMWare licencee since 1999.

QEMU has achieved very good performance since KVM was adopted into the kernel. It's also benefited a lot from VirtualBox, VMWare, and Xen kernel contributions, which mostly improved QEMU's network and display performance, and relatively recently brought USB and PCIe passhrough. These days QEMU can do everything that VMWare can do on a host-by-host basis, but it lacks the infrastructure for massive deployment and management that VMWare has.

RHEV/oVirt is the KVM/QEMU-based alternative to VSphere (Clustered hypervisors, live migration, vGPU etc). I'm interested to see if you can mix it with Gluster to get something like Vsan...

[linuxgeex]

What about using Intel CPU instead AMD one?

The reason to use Ryzen is the cores per dollar advantage. Modern Intel CPUs do support nested virtualization, and have for a few generations now. There's some serious memory performance gains with Ryzen 2, TR4, and Epyc 7002 as well, vs anything from Intel in the same class, thanks to the new branch predictor and the reduced NUMA zones. There's no real performance advantage to PCIe4 quite yet but that will appear over the next year. I expect Intel to counter by jumping directly to PCIe5, but with the hardware you can buy today, AMD is pwning Intel for all but a handful of corner case workloads that have nothing to do with hypervisor-based virtualisation.

If you already own Intel? It's a first-class citizen Qemu/KVM, VMWare. Virtualbox only finally got around to supporting nested HVM a few days ago.

VMWare has supported every release of Windows from '98 on pretty much immediately and with performance in the 80%+ range for most apps other than 3D, since 1999, on both AMD and Intel. I ran WinXP in VMWare with ZoneAlarm, no AV, restore points turned off, but using snapshots to achieve the same result... and I still do that with Win10 and MacOS, currently on Intel hardware at home. Worry less about Intel/AMD or Qemu/VirtualBox/VMWare - get yourself a large amount of RAM. I firmly believe 32GB is the entry point if you want good performance and you want to run any non-trivial workload in a guest and your host, or in 2 guests or more.

Or if you're starting out on a server, ProxMox is a brilliant starting point. Heck it's even a great starting point for a desktop OS if you're comfortable installing Debian from a text-mode installer, and you like the idea of having an HTML5 Web App as your virtualisation GUI, being able to mix/match KVM and LXC containers, live-migrate guests between your host nodes, have a zero-cost virtual KVM/IP setup for your KVM guests, and can live without hardware 3D acceleration in your KVM guests (maybe can turn it on manually after the fact... never tried that.)

[AndyChow]

How is it compared to VirtualBox and VMWare? Specially in terms of features.

One feature people haven't commented on is pure emulation (not hardware accelerated). qemu can virtualize dozens of architectures and hundreds of machines (literally 22 architectures, didn't count the machines). It's been a decade since I've used VirtualBox or VMWare, but last time neither could do that.

It supports with KVM hardware accelerated virtualization with ARM, X86-64, MIPS, Power, PowerPC, s390x. Obviously this is only supported if your host CPU supports hardware virtualization and host/guest architecture match (ex: Power8 for Power KVM)).

The performance of qemu-KVM is much better than VirtualBox (proof) and better than VMware (which you'll never see unless running the tests yourself. VMware bans licensees from publishing any benchmarks about their products. That should tell you something).

As others have mentioned qemu-KVM is linux only. You CAN run vm images from vmware or virtualbox depending on the extension (vdi 1.1, vmdk 3-4-6, vhd).

qemu-KVM supports nested virtualization, which is really cool. I don't if any the two other products do.

I use both qemu and qemu-KVM from the command line only. I've used virt-manager in the past, but all those GUI clicks really take too long. After a while, I figured out how I want most of my machines, and creating a new VM is always just two commands (create the disk, then run the VM with disk and install method). Another command to run the VM without the install method is the final command that I write in a bash script. Whenever I want to run a VM I just run whichever script is associated. If anyone is interested in seeing one of my typical scripts, PM me.

[Chris161]

You can use the VMware gpu driver under Qemu but you won't get 3D accel. unless your using the VMware hypervisor and product. I too have been using VMware Workstation since it came out in 1999. Came across it at a University computer lab. Recently I've been using Qemu with NVIDIA passthrough and Intel GVT-g, and those are better for DX 11 and 12 apps.

[starshipeleven]

Very interesting. And this VMware GPU is fully functional in QEMU? I mean with 2D or maybe even 3D (DirectX10!) acceleration?

How to accomplish such installation? Install in Windows VM proprietary VMware GPU driver extracted from VMware Tools?

It provides 3D with DirectX 10 but it's still remapping it to OpenGL on Linux because of obvious reasons. That's what VMWare workstation does on a Linux host too. It's good enough to run GUIs and applications that need some 3D capability to work, and simple 3D games. Real "serious" gaming is not really possible, but I don't think this "software shenanigans" approach will ever allow that.

https://wiki.gentoo.org/wiki/QEMU/Options#Graphics_card

You need to set the VM's gpu to vmware in its settings

Install xf86-video-vmware in Linux guests, VMware Tools in Windows XP and newer guests.

[Danniello]

Only thing where VMWare has an edge is for the 3D acceleration guest driver, but you can set a QEMU VM to use a "VMware graphics card" to use that driver in a QEMU VM too.

Very interesting. And this VMware GPU is fully functional in QEMU? I mean with 2D or maybe even 3D (DirectX10!) acceleration?

How to accomplish such installation? Install in Windows VM proprietary VMware GPU driver extracted from VMware Tools?

[caligula]

sudo apt install virt-manager
is easier, no need to install PPA either as all is in the repos.

As I said, all will be downloaded and installed automatically.

The complexity of KVM/QEMU/virt-* extends to other aspects as well. There are way more graphics, block device etc. drivers. You need a manual to understand which works the best for you whereas vmware and virtualbox basically provide one good video driver and pretty sane defaults. It supports more disk formats and a bundle of raw images/devices is harder to manage than vmdk extracted from a single VM distribution.

[caligula]

For me the installation of VirtualBox never worked well if you consider kernel updates. Using libvirt was a relieve. And by the way, the setup is not complicated, you just install some packages, modify 2 config files and start the service... but this is for a server install. If you want to use a VM in your home directory, I'm not aware about any setup, you just open Virtual Machine Manager and that's it.

Virtualbox requires the kernel module. If you use a DKMS distro, the same framework should compile it for you after the kernel upgrade. It just works for me.

[timofonic]

VirtualBox is convenient for new virtualisation users since it has packages in major distro repos, a reasonably intuitive GUI, good cross-platform support so your guest isn't trapped on your host if you have Linux, Mac or Windows machines and want to put your guest on a thumb drive or network share. It also has impex for Oracle Cloud if you care about that, and of course it's a first-class Vagrant target, and it supports 'teleport' aka live migration across hosts with different CPU and OS so long as the guest CPU is configured to a subset of the host CPS features.

VMWare is the long-term incumbent, with VSphere. Anyone who complains about VMWare's performance isn't using it right, or they're just using Player and thinking that alone is indicative of the paid product. Every other virtualisation project is basically playing catch-up with VMWare. Full disclosure, I've been a VMWare licencee since 1999.

QEMU has achieved very good performance since KVM was adopted into the kernel. It's also benefited a lot from VirtualBox, VMWare, and Xen kernel contributions, which mostly improved QEMU's network and display performance, and relatively recently brought USB and PCIe passhrough. These days QEMU can do everything that VMWare can do on a host-by-host basis, but it lacks the infrastructure for massive deployment and management that VMWare has. Virt-manager helps bring QEMU closer to the level of ease-of-use for Desktop users that VirtualBox offers. As for deployment and management, ProxMox provides a pretty good starting place for SME's, and I've been using that in place of VMWare for about 6 years at work now. It's not as polished, not by a long shot, but it gets the job done, and for the most part I've migrated the guests to lxc containers these days for performance reasons instead of QEMU.

If you want to run Windows or MacOS as a guest and give it full controll of a GPU or other PCIe card, QEMU is your friend. You'll need a motherboard with IOMMU support and preferably 6+ cores and 32+GB of RAM if you want to make good use of that feature set. Ryzen + 470/570 MOBO recommended, and read up about PCIe reset bugs before buying cards for use in this scenario.

I'm pretty confident that Google Stadia is leveraging QEMU to implement their gaming MAAS platform.

What about using Intel CPU instead AMD one?

[linuxgeex]

How is it compared to VirtualBox and VMWare? Specially in terms of features.

VirtualBox is convenient for new virtualisation users since it has packages in major distro repos, a reasonably intuitive GUI, good cross-platform support so your guest isn't trapped on your host if you have Linux, Mac or Windows machines and want to put your guest on a thumb drive or network share. It also has impex for Oracle Cloud if you care about that, and of course it's a first-class Vagrant target, and it supports 'teleport' aka live migration across hosts with different CPU and OS so long as the guest CPU is configured to a subset of the host CPS features.

VMWare is the long-term incumbent, with VSphere. Anyone who complains about VMWare's performance isn't using it right, or they're just using Player and thinking that alone is indicative of the paid product. Every other virtualisation project is basically playing catch-up with VMWare. Full disclosure, I've been a VMWare licencee since 1999.

QEMU has achieved very good performance since KVM was adopted into the kernel. It's also benefited a lot from VirtualBox, VMWare, and Xen kernel contributions, which mostly improved QEMU's network and display performance, and relatively recently brought USB and PCIe passhrough. These days QEMU can do everything that VMWare can do on a host-by-host basis, but it lacks the infrastructure for massive deployment and management that VMWare has. Virt-manager helps bring QEMU closer to the level of ease-of-use for Desktop users that VirtualBox offers. As for deployment and management, ProxMox provides a pretty good starting place for SME's, and I've been using that in place of VMWare for about 6 years at work now. It's not as polished, not by a long shot, but it gets the job done, and for the most part I've migrated the guests to lxc containers these days for performance reasons instead of QEMU.

If you want to run Windows or MacOS as a guest and give it full controll of a GPU or other PCIe card, QEMU is your friend. You'll need a motherboard with IOMMU support and preferably 6+ cores and 32+GB of RAM if you want to make good use of that feature set. Ryzen + 470/570 MOBO recommended, and read up about PCIe reset bugs before buying cards for use in this scenario.

I'm pretty confident that Google Stadia is leveraging QEMU to implement their gaming MAAS platform.