The CPU usage is always near 90% in my guest system

[ziyuang]

Hi, there.
My host system is Windows Server 2008 R2 SP1 and my guest system is Ubuntu 11.10, with Guest Additions installed. I found that the usage of the CPU (E7200) in guest system is always near 90%, and sometimes it hovers around 100%. I allocate 1GB from my total 6GB ram for my guest system, whose memory usage is about 250MB when idle. Most of the time, the whole computer uses less than 5GB of memory so the memory should be ample for both system. I've tried to set the CPU affinity of VirtualBox.exe, but it doesn't help. Is such a case normal? Thank you.

[Perryg]

Are you running with 3D enabled and the Unity 3D desktop?

[ziyuang]

Are you running with 3D enabled and the Unity 3D desktop?

Yes, with the video memory set to 64MB

[Perryg]

Try with 3D turned off and use Unity 2D. Does it work a lot better?

[ziyuang]

Try with 3D turned off and use Unity 2D. Does it work a lot better?

Yeah~A lot better~~Thank you~

[Perryg]

Figured. Unity uses compiz heavily and add to that Windows memory management and things kind of go south.
You can try to disable fetch/superfetch on the Windows host and make sure that your hosts virus software *does not* scan the folder that houses your VDI files and that will help a lot if you want the 3D features of Unity. But I would give the guest only 32 MB of vRam since the video of the guest is really using the hosts RAM. That seems to be about all you can do.