Qemu vs VMWare
Marko Vojinovic
vvmarko at gmail.com
Sun Oct 25 21:05:32 UTC 2009
Hi everyone! :-)
I wish to share my first hands-on experience with qemu, compare it to vmware
player, and (since I'm highly disappointed with the performance difference) ask
is there anything that can be done configuration-wise to improve the user
experience under qemu.
Basically, my motivation to try out qemu in the first place is the not-so-great
support from vmware when it comes to kernel modules, updating Fedora etc. The
idea is to make all these issues go away by going with the open source
solution for virtualization. Naively, I expected more or less equivalent
performance and/or set of features. But qemu turned out to be a very big
disappointment:
(1) Windows XP guest under qemu appears to be an order-of-magnitude slower
than equivalent vmware guest. I haven't measured precisely, but by counting
the seconds for the same operation (open a window or such), qemu appears to be
roughly 10 times slower! Why is it *that* bad?
(2) When resizing the guest console window, qemu rescales the guest output,
while vmware resizes guest screen resolution to match the window size. The
latter looks far more pretty.
(3) There is no transparent clipboard usability (copy-paste) between host and
guest in qemu.
(4) Set of supported hardware for guest is smaller in qemu (no bluetooth, no
webcam, ...).
(5) There is no equivalent of the "unity" display of guest windows on the host
desktops, which works so beautifully in vmware, even more so if Compiz effects
are enabled on the host.
There are a few more minor quirks (selinux complaints, failure to shutdown
guest properly, etc.), but I can live with those, so I won't complain. But the
above five issues, (1) and (3) being most severe, are showstoppers. So my
questions are:
* did I miss something obvious to configure, read the docs or whatever, so I'm
not aware that qemu can work better?
* I am used to think that typically open-source solution of something is more
powerful than any proprietary solution of the same thing, but in this case
(virtualization) it seems to be the other way around. Why? I doubt that open-
source developers are incompetent to deliver equivalent functionality, so what
is the problem here? Patented solutions, maybe? I mean, host-guest copy/paste
is an obvious useful thing to have, for example...
I am not trying to bitch about qemu being so bad, but am rather genuinely
interested in understanding why.
Also, I think I should mention that my processor does not have the vmx bit, I
have no option in the host bios to enable it, so I guess both qemu and vmware
work in all-software emulation. But that doesn't explain such a big difference
in performance. Btw, this is all on Intel Core 2 Duo 1.5 GHz, 2GB of ram, each
guest has one processor and 512 MB ram allocated. They don't run
simultaneously, of course. I didn't notice any memory swapping activity.
I would appreciate if someone sheds some light for me on this. I would prefer
to use qemu (it being open-source), but it performs so much worse that I have
to fallback to vmware for now.
Ideas? Opinions? Advice?
TIA, :-)
Marko
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