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Old 05-25-2013, 07:12 PM   #1
manwichmakesameal
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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.
 
Old 05-25-2013, 07:31 PM   #2
kfritz
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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.
 
Old 05-25-2013, 09:52 PM   #3
zakame
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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*.)
 
Old 05-25-2013, 10:35 PM   #4
gezley
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Quote:
Originally Posted by manwichmakesameal View Post
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.
 
Old 05-25-2013, 10:40 PM   #5
zakame
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Yep that last bit is important especially for ThinkPads. IIRC hardware virtualization is usually disabled by default.
 
Old 05-26-2013, 10:17 AM   #6
manwichmakesameal
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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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