Skip to content

Why PV-Paging is faster in Xen:

March 3, 2011

Paravirtualization

A term used to describe a virtualization technique that allows the operating system to be aware
that it is running on a hypervisor instead of base hardware. The operating system must be
modified to accommodate the unique situation of running on a hypervisor instead of basic
hardware.

Hardware Virtual Machine (HVM)

A term used to describe an operating system that is running in a virtualized environment
unchanged and unaware that it is not running directly on the hardware. Special hardware is
required to allow this, thus the term HVM.

Since the Domain Kernel Knows that that hypervisor is running below it. It directly interacts with hardware.
So the Request are handled in following sequence:
Domain Kernel (Xenified )—> Hypervisor –>Hardware

In case of other Hypervisor like KVM where host kernel is running below hypervisor, request are handled in following sequence:
Domain Kernel –> Hypervisor –> Host Kernel –> Hardware

From above it is easily understandable that pv-paging is faster since an indirection of guest kernel is removed.

Advertisements

From → Kernel, Linux, Xen

Leave a Comment

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: