The Phoronix Test Suite is designed to test a (client) operating system out of the box and it does a good job at that. It's certainly valid to run PTS inside a virtual machine but you you're going to need to tune the host, in this case Karmic. The way you'd configure a client operating system to a server is obviously different, for example selecting the right I/O elevator, in the case of KVM you'll certainly see benefits there. You'd also want to make sure that the guest OS has been optimally installed - for exmaple in a VMware environment you'd install VMware tools - in KVM you'd ensure that you're using VirtIO in the guest for the same reason. They you'd also look at optimizations like cpu pinning, use of huge pages, etc. Just taking an generic installation of Karmic out of the box and running VMs isn't going to give you real insight into the performance of KVM. When deploying Linux as a virtualization host you should be tuning it. It would certainly be appropriate to have a spin of Karmic that was designed to run as a virtualization host. Maybe it would be more appropriate to actually run the test in a tuned environment and present some results rather than ask a developer to prove KVM is working. > The test itself is a simple usage of SQLite. It is stock KVM as > available in 2.6.31 on Ubuntu Karmic. So it would be the environment, > not the test. > > So assuming that KVM upstream works as expected that would leave > either 2.6.31 having an issue, or Ubuntu having an issue. > > Care to make an assertion on the KVM in 2.6.31? Leaving only Ubuntu's > installation. > > Can some KVM developers attempt to confirm that a 'correctly' > configured KVM will not demonstrate this behaviour? > http://www.phoronix-test-suite.com/ (or is already available in newer > distributions of Fedora, openSUSE and Ubuntu. > > Regards... Matthew On 9/24/09, Avi Kivity <avi@xxxxxxxxxx> wrote: > On 09/24/2009 03:31 PM, Matthew Tippett wrote: >> Thanks Avi, >> >> I am still trying to reconcile the your statement with the potential >> data risks and the numbers observed. >> >> My read of your response is that the guest sees a consistent view - >> the data is commited to the virtual disk device. Does a synchronous >> write within the guest trigger a synchronous write of the virtual >> device within the host? >> > > Yes. > >> I don't think offering SQLite users a 10 fold increase in performance >> with no data integrity risks just by using KVM is a sane proposition. >> > > It isn't, my guess is that the test setup is broken somehow. > > -- > Do not meddle in the internals of kernels, for they are subtle and quick to > panic. > > -- Sent from my mobile device -- 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 -- 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
