[Discuss] virtualization overhead

[richb at pioneer.ci.net (Rich Braun)]

I  wrote:
>> Performance is equal to or possibly better than the bare-metal,


Rich Pieri wrote:
> This is not possible.  ... emulation incurs a small processing overhead
> so virtualized I/O can never be as fast 

Run a benchmark, come back and post your numbers. Then let's compare. (I did, and long-time members of this list might remember that thread.)

As for how it could be possible: CPU performance far exceeds that of any current I/O. So emulation overhead drops way below the roughly 3% CPU overhead that I recall measuring. Throw a big RAM cache underneath your VM, and you can get blazing fast numbers.

I don't work in hardware any more so I'll leave it to others to suggest solutions based on their more recent/greater expertise. I did find via numerous benchmarks that a Linux host OS outperforms Windows, and that the LVM2 volume manager on the host OS is the only way to get decent IO performance out of virtual images.

-rich