On 9/11/2009 at 9:46 AM, Javier Guerra <javier@xxxxxxxxxxx> wrote: > On Fri, Sep 11, 2009 at 10:36 AM, Bruce Rogers <brogers@xxxxxxxxxx> wrote: >> Also, when I did a simple experiment with vcpu overcommitment, I was > surprised how quickly performance suffered (just bringing a Linux vm up), > since I would have assumed the additional vcpus would have been halted the > vast majority of the time. On a 2 proc box, overcommitment to 8 vcpus in a > guest (I know this isn't a good usage scenario, but does provide some > insights) caused the boot time to increase to almost exponential levels. At > 16 vcpus, it took hours to just reach the gui login prompt. > > I'd guess (and hope!) that having many 1- or 2-cpu guests won't kill > performance as sharply as having a single guest with more vcpus than > the physical cpus available. have you tested that? > > -- > Javier Yes, but not empirically. I'll certainly be doing that, but wanted to see what perspective there was on the results I was seeing. And I've gotten the response that explains why overcommitment is performing so poorly in another email. Bruce -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
