VMWare Performance/VMI

[jonathan.penrose]

Anyone turned on VMI in the VMware image and tested performance difference under VMWare Server 2.0?

Doesn't appear that VMI is enabled in the kernel included with the VMWare image. This should improve (often significantly) the performance of the virtual machine as it makes the kernel hypervisor aware. Is this because of known problems or just not tested?

Ubuntu ships with VMI turned on by default - as Untangle is known to run successfully on Ubuntu, I wouldn't expect this would cause a problem. ?

Whether a given virtual machine actually USES the VMI extensions is handled in the configuration of the virtual machine...

Thanks!

[sky-knight]

I don't know if that is wise. I would be interested in seeing it tested but don't forget that you are virtualizing a virtual system...

99% of Untangle's magic is made possible by the UVM, this is a Java Virtual machine at the heart of every Untangle installation. So you're already abstracting that code, then you do it again to make the thing fit within VMWare. So now you want to make the linux install "know" that it's in a VM? When it itself is running a VM?

I smell race conditions....

[jonathan.penrose]

Sky-night,

The VMI extensions allow an OS running in VMWare to take advantage of hardware support for virtualization - the primary benefit of this is better performance - it moves much of the management overhead of virtualization directly to hardware and can significantly reduce the 'cost' of context switching - which is one of the primary performance penalties of virtualization...

This is called para-virtualization and is one of the key ideas behind the hypervisor model used by both Xen/Citrix and Microsoft...

It is implemented by making a few changes in the core OS (which are already incorporated into the core Linux kernels) - Basically this is just a way to make virtualization work better - theoretically it should improve both the performance and reliability of running Untangle in VMWare...

[MrxCrp]

jonathan.penrose,

If you test this, please report back your findings.

Thanks

[jonathan.penrose]

Well... We have been testing with the Dell SC440 with Xeon processors that supported Intel's VT extensions - now that Dell is phasing this model out, we are testing the T100 - with the extra performance (and cost) this is a lower priority now, but we will post back what we find...