paravirtualisoitu

Paravirtualization is a technique in virtualization that involves modifying the guest operating system's kernel to make it aware it is running in a virtualized environment. This modification allows the guest OS to interact directly with the hypervisor in a more efficient manner, bypassing the need for hardware emulation for certain privileged operations. Instead of trapping and emulating hardware instructions that would normally be handled by the physical machine, a paravirtualized guest can issue special hypercalls, which are calls directly to the hypervisor. This direct communication reduces overhead and improves performance compared to full virtualization, where the hypervisor must intercept and translate all guest instructions.

The primary benefit of paravirtualization is enhanced performance, particularly for I/O-intensive workloads. By allowing the guest to communicate directly with the hypervisor for operations like disk access or network communication, the latency associated with hardware emulation is significantly reduced. This can lead to a much more responsive and efficient virtual machine. However, a drawback is that paravirtualization requires modifications to the guest operating system. This means that standard operating systems might not work out-of-the-box with a paravirtualized hypervisor unless they have been specifically adapted. Xen is a well-known example of a hypervisor that heavily utilizes paravirtualization. Modern hypervisors often employ a hybrid approach, using paravirtualization where possible for performance gains while falling back to hardware emulation for instructions that cannot be paravirtualized.