X11 operates too slowly in openSuSE 11.2 without VT-x/AMD-V

[Eugene]

Host: Windows XP SP3 Pro x86

Guest: openSuSE 11.2 x86

VirtualBox: 3.1.4

Operations with GUI elements in the guest OS are performed very slowly if VT-x/AMD-V is turned off (or simply not available on the PC). This issue shows up even while I am hovering the mouse pointer over the items in the main menu, scroll a document in OpenOffice or a web page in Opera or Firefox, etc.

This issue has been spotted on two PCs, one of which does not support hardware virtualization at all, the other one does. On the latter machine, the performance of the operations mentioned above was checked both with using VT-x/AMD-V disabled and enabled in the setting of the virtual machine.

Here is what the output of top command in the guest shows.

1. Using VT-x/AMD-V is disabled in the settings of the virtual machine or not available at all, the guest system is idle:

Total CPU load (on average):

user-mode code - 1%, kernel-mode (except for interrupts) - 10%, servicing hardware interrupts - 0%, idle - the rest.

Among the running processes CPU is mostly used by Xorg (4-6%).

So far, so good

2. VT-x/AMD-V disabled or not available, hovering over GNOME or KDE main menu in the guest:
   

Total CPU load (on average):

user-mode code - 10%, kernel-mode (except for interrupts) - 70%, servicing hardware interrupts - about 20%, idle - nearly 0%.

Among the running processes CPU is mostly used by Xorg (40-50%) and the corresponding application, MainMenu, for example (20-25%).

Launching a GUI-intensive application like Opera or OOo is thus a real pain.

3. Hardware virtualization support is available and using it is enabled in the settings of the virtual machine, hovering over GNOME or KDE main menu in the guest:

Total CPU load is less than 10-15%.

CPU is mostly used by Xorg again but now it is only 5-7%, which is acceptable.

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The above data were nearly the same on the virtual machines without VirtualBox guest additions and with VirtualBox guest additions (version 3.0.8) provided with openSuSE.

[NB] I was unable to check the issue with the guest additions from VirtualBox 3.1.4 distribution. I have tried several times to install them (with or without uninstalling the previous additions, with different xorg.conf variants or without xorg.conf at all, etc.) but either X11 refused to start or both mouse and keyboard did not work after reboot, even Host+F2 and the like did not work. The absense of xorg.conf by default on openSuSE 11.2 also does not make life easier in this case. Experiments with SaX made no good too.

Anyway, the problem with guest additions is another story and is probably beyond the scope of this ticket. What is really annoying, is the sluggishness of X11 without hardware virtualization support.

[Eugene]

Log from the machine without VT-x and AMD-V