Hi Gianluca,
On Fri, 2009-04-24 at 09:15 +0200, Gianluca Sforna wrote:
Hi all, sorry for the slightly off topic post, but I'm looking for some definitive answers here. A couple days ago, I performed a "boot race" with Fedora 11 and Ubuntu 9.04, thinking it would be the easiest way to visualize which is faster to boot in a default installation. So basically, I created two identical VMs with virt manager and installed both from the liveCD, then fully updated them. The recorded boot sequence was repeated multiple times to see if results were consistent.
That's crazy talk! How could you possibly hope to get any useful results from such a stupid experiment. VMs aren't real machines, dude!
Now, of course I hit a nerve there, because I had many complaints, ranging from the video being a fake, to personal attacks, to more or less weird attempts to explain why Fedora booted faster.
Fedora booted faster? Wait, I take it back, that's a wonderful experiment! :-)
The most common complain was that competing for the host's resources was not fair, something along the line: Fedora starts first becasue has no grub, grabs some critical resource and Ubuntu has to wait for it before continuing.
So basically the question is: do you think there could be any reason why such a test can be unfair to one of the VMs?
Okay, seriously - I think it's a reasonable experiment.
However, the fact that you have two guests competing for resources is always going to make people suspicious. It may well be a deterministic experiment, but you're always going to have a hard time convincing people of that.
Personally, I'd do it by timing each VM on its own and comparing the boot times.
Also, I personally wouldn't be interested in which is faster boot, but rather what the bottlenecks are in both cases and how to make them both boot faster.
Cheers, Mark.