Problem with QEMU and Virtual Machine Manager after updates, guest machine slow

[otnateos]

Hi,

Basically I used to had a Windows XP guest and works well. However after few updates of libvirtd, etc, etc, and including my stupid combination to re-add the guest image somehow the Windows XP guest run far slower.

I only notice that previously my guest saying the processor as QEMU 2.4GHz, now it says Pentium II 2.4GHz.

I wonder if someone could point out to specific way to edit settings for Qemu guest machine in Virtual Machine Manager, or even help me to find quick fix to my problem. Thanks

[webaware]

It sounds like you no longer have /dev/kqemu loaded. Have you also had a kernel update? This is what usually does it - you probably don't have kqemu module for your new kernel.

I have a routine of rebuilding / reinstalling the kqemu and nvidia modules every time I get a kernel update. See here for a simple guide to QEMU and kqemu.

[otnateos]

I did have the kernel update and I didn't have kqemu module for my kernel. I think if I remember correctly I never use kqemu previously so the problem might not with the kqemu.

I tried to install kqemu and use my normal way to run my virtual XP and still doesn't improve the performance.

[webaware]

Ah, I didn't catch it before - you're running from the Virtual Machine Manager. If you ticked the option for "kernel / hardware acceleration" that means you're running KVM (qemu-kvm). Or you were, when it was faster. You should check for /dev/kvm to see if this kernel module is still being loaded, as it sounds like maybe it isn't.

I played around with the VMM briefly one afternoon recently, and couldn't see where you can switch this setting on / off after the fact, but maybe there is a way to do it from the shell - see here for more information about managing VMM from the shell.

Alternatively, you could try to run KVM directly from the shell without messing about with the VMM. It allows you to specify lots of options, and you'll also get to see the output of KVM which might tell you what's going wrong. Run KVM just like QEMU, except specify qemu-kvm instead of qemu. e.g.

qemu-kvm -m 512 -hda /path/to/your.img

[otnateos]

Hey thanks webaware,

I was thinking I could simply use VMM and don't worry about configuration and such, and from your post I just realised that my VM was using qemu instead qemu-kvm to run it (even though I have specified to use kernel/hardware acceleration).

I changed the emulator in the configuration and the speed returns back to normal. I guess something is not really set well on the current version of VMM that I'm using. I can't even shutdown my VM. Well that's another matter.

Thanks again for your guide.

[sideways]

wow, qemu-kvm really is much faster. I just booted a F8 liveCD iso image in 30 secs!

yum install kvm

Then I rebooted (I probably could have just loaded the relevant kernel modules kvm, kvm_intel)

qemu-kvm -m 512 -cdrom /data/F8LiveCD.iso

Thanks for the tip, I'll be using it from now on. stevea posted a while back about the latest kvm modules being even faster, I'll have a look at that when I get the time.

[webaware]

Yay! Good to hear all is working fast again. And glad that sideways is ripping along now too!