The new host kernel networking backend, vhost, is a fully supported feature in Red Hat Enterprise Linux 6.1. vhost provides superior throughput and latency over the userspace implementation.
The qcow2 image format now supports caching of metadata. Additionally, support is added for live snapshots using external qcow2 images.
ioeventfd is now available, providing faster notification of block I/O.
The KVM hypervisor in Red Hat Enterprise Linux 6 features Kernel SamePage Merging (KSM), allowing KVM guests to share identical memory pages. Page sharing reduces memory duplication, allowing a host with similar guest operating systems to run more efficiently.
PCI configuration space access is improved, enabling a broader set of PCI devices to be device-assigned to guest VMs.
In Red Hat Enterprise Linux 6.1, the Time Stamp Counter (TSC) synchronization can now be automatically detected on guest bootup or when a host CPU is hot-plugged. Additionally, the TSC synchronization frequency is adjusted after a live migration.
Additionally, the new
drive_del command allows libvirt to safely remove a block device from a guest.
- The maximum display resolution on qemu-kvm is now 2560x1600 pixels
- Red Hat Enterprise Linux 6.1 includes the ability to expose an emulated Intel HDA sound card to all guests. This update enables native sound support for many guests including the 64-bit version of Windows 7
- QEMU char device flow control is enabled
- Message Signaled Interrupts (MSI) implemented for the win-virtio-blk driver
- A new standard interface for selecting/prioritizing the boot devices of the guest
- Stability improvements for live migration
- QEMU userspace static tracing
- Virtual disk online dynamic resize feature
- Forbid pci hot unplug of critical devices such as gpu, pci bus controller, isa bus controller