This is a post from several months ago that I made on the 64–bit Advantage blog. Since now we’re working with virtualization (at the time it was only an interest of mine), I think it is worth it to re-post it here:
I wanted to make a brief mention of the Virtualization Technology that is being introduced in the latest generation of Intel CPUs (known as VT-x). This technology was formerly known as "Vanderpool", and it is already available on some Pentium 4, Pentium D, Xeon and Core Duo CPUs. Later this year it will also be available on the next generation Itanium CPUs, using a technology known as "Silvervale".
I was talking with a coworker the other day about this technology, and our main question was "What is it exactly that it does? What advantage would it have over traditional software virtualization?" Well, to answer these two questions:
On a virtualization environment, there's the Virtual Machine Monitor (VMM), which handles the processor and physical resources of the machine, and the Guest Software, which operate inside a Virtual Machine handled by the VMM. VT-x introduces 10 new intructions to the architecture for facilitating the tasks of the VMM. Some of them, such as VMLAUNCH and VMRESUME, allow the VMM to start/enter running VMs, or VMON/VMOFF, turns the Virtualization functionality on and off.
The main reasons for using VT-x over software virtualization are speed and reliability. With hardware support, you are pretty much creating the equivalent of a hardware partition for the Guest Software, which improves both the performance and the robustness of the VM - and this is vital for consolidated server environments, one of the areas where VT-x is expected to be heavily used.
Now, one thing- why mention Intel's VT-x on this site? Well, one of the strenghts of 64-bit computing is that with more resources available on a single box, it is easier to to consolidate servers. With the new support for virtualization on the CPUs, you can use Virtual Machines for consolidation, so each software server has its own isolated environment without sacrificing performance.
More information here.