Qemu vs VMWare

Marko Vojinovic vvmarko at gmail.com
Mon Oct 26 12:12:45 UTC 2009


On Monday 26 October 2009 04:15:34 Tony Nelson wrote:
> The way recommended by QEMU developers is to use KVM, purchasing new
> hardware that supports KVM if necessary, in which case you won't need
> to use much of QEMU.

Right, but my idea of having a virtual machine in the first place is to avoid 
buying more hardware. And this being a laptop here, I'm afraid I cannot 
upgrade the processor. So far I've been using vmware, since it is more 
convenient than dual boot setup, but whenever a new kernel comes out I get 
into trouble of recompiling modules to match. That is why I am trying to go 
with qemu instead.

> Good performance on other hardware requires the
> kernel module kqemu.  The QEMU developers have deprecated kqemu and are
> removing it from the next version (.12 IIRC), but you can currently
> still use kqemu if you build QEMU with kqemu enabled.

Oh, a kernel module? Now you're talkin'! :-) I didn't know about this. If 
there is a kernel module needed, then that accounts for the performance 
difference between vmware and qemu, since vmware has these modules up and 
running, while qemu does not. There is also this question of vmware-tools 
package being installed in its guest, while qemu does not seem to have a 
similar thing.

Ok, so I did a yum search and a yum install kqemu, which pulled in appropriate 
kmod packages and all. Then I started the qemu guest to see what happens. But 
the module did not get loaded (lsmod doesn't report it). I shutdown the guest, 
loaded the module manually via modprobe (which worked), checked that it is 
loaded, started the guest again, and went to see if there is any performance 
difference. But there wasn't.

So I wonder how to use the kqemu module? Or rather, how to explain to qemu 
that there is a module loaded and that it should use it? There is nothing 
obvious in the GUI about this, where do I set it up?

If default Fedora rpm version of qemu is *not* built with kqemu enabled, then 
that is very unfotunate, since I don't want to recompile the whole qemu in 
order to avoid recompiling vmware modules. That would defeat the whole point 
of using it in the first place.

So can you tell me how to get the kqemu module to work?

> I have just switched from QEMU to VirtualBox (with RPMFusion enabled,
> `yum installVirtualBox-OSE`) and can recommend it,

Yes, VirtualBox is the next candidate, after I evaluate qemu. I'll try it out, 
eventually.

> unless your VM needs
> access to your actual USB devices or needs to be controlled remotely,
> as those features are not open source.

Well, now... It would be nice to be able to use usb, bluetooth, and such. One 
of my main use cases for a windows guest is to communicate with my cell-phone 
(via usb or bluetooth) using appropriate software (for Samsung phones...). But 
anyway, I'll give VB a try, just to see how it performs on my hardware.

Best, :-)
Marko




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