[SATLUG] kvm problems

Mark Mayfield mayfield_mark at gvtc.com
Sun Dec 22 11:14:06 CST 2013

I don't know if it affects Windows clients very much but I've read that 
using hugepages helps. I implement it in the libvirt guest xml file. 
Also you may want to play around with the hard drive controller format 
options (IDE, SATA, libvirt). Their is a disc out there, I believe on 
the Fedora KVM page for a floppy image with the libvirt drivers on it 
you can use during install to detect the libvirt hard drive (in 
Windows). I'm also aware of a nasty bug that was out there for certain 
qemu/kvm versions where using two logical cpu's in the guest would slow 
the machine to a crawl. If you're using two try running it with 1 or 3. 
The libvirt drivers can be buggy to. I recently had to revert a couple 
of guests off of libvirt due to crashes. Video I think is the biggest 
factor in speed. SDL is very good but you get no remote access to it. 
Spice/QXL works really well although it crashes guests in some 
instances. Cirrus would be third. Several guests on the same machine and 
lots of disk access by other services could cause problems also. Do you 
have lots of RAM? Make sure you have enough for the host and all the 
memory you allocate to guests.

On 12/22/2013 08:51 AM, Borries Demeler wrote:
> Thanks Ron and Bruce for your responses! It turned out that installing the latest version of
> qemu (1.7.0) got me past this error.
> However, I haven't figured out how to make the vm's work at any reasonable
> speed, right now there seem to be other issues I need to work through. Trying
> to load an existing machine prevents input to the machine, and trying to create
> a new machine is really slow, which is surprising, since this is a fast computer.
> Any additional thoughts that could make it work faster?
> -b.
> On Sat, Dec 21, 2013 at 03:59:59PM -0600, Bruce Dubbs wrote:
>> Borries Demeler wrote:
>>> I am trying to get kvm to run on my laptop (intel I7 with vmx extensions)
>>> and am running into issues trying to run virt-install to set up a new kvm
>>> image.
>>> I have downloaded and installed from source all the relevant libraries and
>>> programs,
>>> so that libvirtd (ver. 1.2.0) starts up without error, virtualization is
>>> enabled in the bios
>>> (multiple power cycles after enabling), and the kvm-intel module is loaded.
>>> Yet, when running a command like
>>> virt-install -r 2048 --accelerate -n win7 -f /home/kvm-images/win7.img
>>> --cdrom /dev/cdrom
>>> I keep getting: ERROR    Host does not support any virtualization options
>>> In fact, it doesn't matter what command line option I give to virt-install,
>>> the error is always the same.
>>> I searched google to no avail (so far). Some suggestions say that RHEL
>>> versions were
>>> mixed to cause this problem, but my laptop is a 03/13 slackware-current64
>>> distro installed
>>> that is kept updated (64-bit with 32-bit extensions). Other suggestions
>>> are the lack of
>>> virtualization support in the bios or cpu, both of which I checked to be
>>> in order.
>>> Kernel module is loaded and /dev/kvm exists. There are no libvirtd errors
>>> logged.
>> kvm has been incorporated into qemu.
>> Try the instructions at
>> http://www.linuxfromscratch.org/blfs/view/svn/postlfs/qemu.html
>> the instructions for installing a distro are there, but afterwards I
>> create a script to run with all the options.  For instance, to bring up
>> my debian instance I use:
>> $ cat start-deb2.sh
>> #!/bin/bash
>> SUDO=sudo
>> [ $EUID == 0 ] && SUDO=
>> $SUDO qemu -enable-kvm -boot c \
>>             -drive file=/mnt/qemu1/debian2.img,if=virtio \
>>             -m 2G \
>>             -net nic -net tap -machine accel=kvm
>> Getting networking up can be tricky.
>>    -- Bruce
>> -- 
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