[GLLUG] How can a VM be faster than raw hardware?

Paul Hewlett phewlett76 at gmail.com
Sun Dec 9 19:08:54 UTC 2012

Hi John

Virtualbox lies - see this link

Virtualbox does not honour sync/fsync requests - your data may be at risk...


On 9 December 2012 17:27, John Winters <john at sinodun.org.uk> wrote:

> I've just noticed something odd which puzzles me.
> For a while I've been developing a Rails application, using rspec to run
> the automated tests.  It's at an early stage, but to run the 212 examples
> on my development machine currently takes about 38 seconds.
> The machine has a Core i5 3570K (3.4GHz), 16G of RAM and an SSD providing
> the development area.
> Because I need to play with it elsewhere, I just git cloned the source
> onto a Linux virtual machine running under VirtualBox on top of MacOS on a
> laptop.  The laptop is a much lower spec - 2.4 GHz Core 2 Duo, with only 1G
> of RAM available to the VM (4G in the machine in total), and a conventional
> spinning HDD.
> I was concerned about how long the test suite would take on the laptop,
> but to my surprise it runs in only 29 seconds.
> Anyone any idea why the lower spec machine would be so much faster?
> Cheers,
> John
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