More organizations are using VDI (virtual desktop infrastructure) technology, in which thousands of desktops are streamed to users. Servers now can come with 128 or 256 processor cores, making them prime candidates for running thousands of VMs.
Also, the emerging class of cloud operating systems, such as MirageOS and OSv, would also benefit from the ability to run thousands of VMs on each server. These OSes are geared towards running thousands of smaller VMs that do one thing each, rather than running fewer multipurpose VMs, Dunlap said.
Another new feature is that Oracle provided a speedy new virtualization mode, available in preview form in this release. It extends Xen's natural paravirtualization (PV), in which the VM can talk directly to the hardware, cutting out the emulation layer that can slow other hypervisors. Oracle's version of PV, called PVH, uses the native hardware virtualization extensions on Intel x86 processors to speed system calls, page table lookups, and boot and I/O operations.
Development of Xen is managed by the Xen Project, under the management of the Linux Foundation. Amazon EC2, Rackspace Cloud and other cloud services use Xen for their operations. The Xen Project estimates that the hypervisor has been used by over 10 million users.
Amazon, AMD, Analog Devices, Broadcom, Citrix, Fujitsu, Intel, the National Security Agency, Oracle, Suse and Verizon/Terremark all submitted significant amounts of code for this release. Academic and independent developers also contributed to the project.
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