Thursday, October 12, 2006

Running Linux under Xen: VT hardware harmful?

If I add up everything I read, the new VT chips from Intel (featuring new hardware virtualization technology) do not enhance the speed of Xen hypervising Virtual Machines loaded with Linux ... beyond the fact that the chips are faster. In fact, the performance is allegedly worse, so the price/performance is hypothetically much worse.

In the October 2006 Issue of the UK's Linux Format magazine, their benchmarks show Linux with Xen on hardware virtualization chips to be about 50% the speed as native Linux! But, in Steve Hand's dynamic BayLISA lecture on Xen last year, he benchmarked Xen domains without virtualization hardware to be close to 100% native speed.

So what's up?

I can only guess that using the VT hardware takes significant overhead.

It offers benefits, of course! You can run unmodified Windows images, trapping the infamous "odd opcodes" and passing control to the hypervisor (the virtual machine manager). You also get more flexibility to run simultaneous x86 modes.

I have to look into this more.


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