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-   -   KVM, libvirt and virtmanager really slow or just me? (http://www.linuxquestions.org/questions/slackware-14/kvm-libvirt-and-virtmanager-really-slow-or-just-me-4175463437/)

manwichmakesameal 05-25-2013 07:12 PM

KVM, libvirt and virtmanager really slow or just me?
 
Ok, so I've been using vm's for a while now. I have in my server rack 2 machines for doing them and they both run VBox for them. So one day I decided to put a 3rd box in and put CentOS on it. It introduced me to virtmanager. I decided to try it out on Slack on my laptop (Lenovo T510, Core I5, 4G RAM). I'm trying to install Slack in a vm, and it is PAINFULLY slow, as in taking ~8hrs or more for install. Anyone know any tricks to speeding this up? Am I missing something? Basically the process I used was: install libvirt, then install virtmanager, run vm. Any help is welcome.

kfritz 05-25-2013 07:31 PM

I have no experience with VirtualBox, libvirt, or virtmanager, but I use qemu/KVM. Slow installs had everything to do with how the disk was configured for caching. On Qemu, the defaults are slow for installs, so I use "cache=writeback". Take a look at your documentation and see what caching models they support.

zakame 05-25-2013 09:52 PM

Are you using virtio? Are you creating your VMs with the right --os-type and --os-variant?

If it is an existing VM, you probably need to redo its libvirt configuration to use virtio, and also redo the VM's fstab (as virtio block devices will show up as /dev/vd* instead of /dev/sd*.)

gezley 05-25-2013 10:35 PM

Quote:

Originally Posted by manwichmakesameal (Post 4958912)
Ok, so I've been using vm's for a while now. I have in my server rack 2 machines for doing them and they both run VBox for them. So one day I decided to put a 3rd box in and put CentOS on it. It introduced me to virtmanager. I decided to try it out on Slack on my laptop (Lenovo T510, Core I5, 4G RAM). I'm trying to install Slack in a vm, and it is PAINFULLY slow, as in taking ~8hrs or more for install. Anyone know any tricks to speeding this up? Am I missing something? Basically the process I used was: install libvirt, then install virtmanager, run vm. Any help is welcome.

Make sure the kvm modules are loaded on the host machine:

Code:

lsmod|grep kvm
If not, try this (select second option according to your CPU):

Code:

modprobe kvm
modprobe kvm-intel | kvm-amd

Make sure as well that the host processor has virtualization extensions, and that they are turned on in BIOS.

zakame 05-25-2013 10:40 PM

Yep that last bit is important especially for ThinkPads. IIRC hardware virtualization is usually disabled by default.

manwichmakesameal 05-26-2013 10:17 AM

Kernel modules are loaded. There is no option for Slackware with virtmanager when creating vm's. I just use generic >2.6* option. Changing the caching mode to writeback did seem to have a little improvement. Guess I'll have to keep tweaking it.


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