Linux as a Hypervisor
Linux Advantages as a Hypervisor
Andrea Arcangeli
Monday, July 21, 2008 01:29:06 PM
For example, once the hypervisor needs to become multicore aware, NUMA aware,
able to SWAP with its own aging algorithms that detect the working set of
each guest OS, able to keep the CPU in C4 state and at the lowest frequency
the whole idle time, able to support CPU hotplug, memory hotplug, suspend to
ram, and all other sort of features that a real OS has to support, Linux
becomes a perfect fit to be the hypervisor itself as it solves all those
problems already.
To make a few examples of the practical advantages of using Linux as
Hypervisor, I was amazed how clean it was to allow KVM to swap reliably the
entire guest memory in only a few weeks of work by taking avantage of the
core Linux virtual memory management to do all the aging and working set
calculations.
I'm also pleased of how the 2.6.24 kernel of my Penryn laptop that suspends
with s2ram automatically with acpid when I close the lid, and it consumes
only 0.5watts until I open the lid again. It continues playing YouTube video
and audio inside KVM whenever I open the lid with only a few lines of KVM
being aware of the suspend and resume to disable vmx/svm mode while the CPU
is suspended.
I noticed that the design that requires the lowest effort to quickly reach
equal or superior features usually wins the marketplace as it tends to be
the most efficient and stable over time. I guess this is why we're not
using IA64 laptops just yet.
Resources
Andrea Arcangeli is a kernel hacker and coder extraordinaire, and he works for Qumranet.
The Best Virtualization Program You've Never Heard Of, part 1
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