The Great Virtualisation Secret

Massive Performance Increase

By implementing virtualisation in the host operating system, you are effectively cutting out the middle man (i.e. a third party virtualisation software).

By implementing a virtualised aware OS, you have more direct access to core processes without the need for any emulation components due to the binary patching in the guest OS code.  

One operating system that makes good use of paravirtualisation is the RHEL O/S – ie the Red Hat Enterprise Linux edition which has gains of between 20%-50% over other implementations of virtualisation. 

If we were to take the minimum 20% increase – it is still a massive increase over third party virtual software.

Dynamic Resource Allocation

Paravirtualisation can also take advantage of the extra functionality provided by the CPU such as the dynamic allocation of memory resources between the host machine and the guest operating systems.

Dynamic allocation has been available previously but not at the speed given by paravirtualisation.

In other words, it is easier to dynamically allocate essential resources such as memory, hard disk size and processor time, when each virtual machine requires it either automatically via the host OS or via a script.  

Say for example you have a pool of resources and two virtual machines VM1 and VM2.  Several processes have just completed and terminated on VM1 thus freeing up memory that can be re-used in either VM1 or VM2.