Ubuntu in Virtual Box slows way down . . .

[sqcomic]

I'm running Ubuntu in a virtualbox on a Windows 7 host. It works great - except after I start up the machine, the response to keystrokes and updating of the screen slows way down. It gets slower and slower until it is unbearable after about an hour. If I save the machine state and reload it, things work great again - so it sounds like a virtualbox problem, not an ubuntu problem.

Do other people who run Ubuntu in a virtualbox see this behavior? Do other people who run virtualbox in Windows 7 see this? Does anyone know how to fix this?

[MikeTbob]

What are your machine specs? How much RAM? Are you using shared video memory?

[Rubberman]

In addition to what Mike Tbob asked, also which version of Ubuntu are you running? Also, go into the BIOS and make sure you have enabled hardware support for virtual machine hypervisors and enable the VT-s/AMD-V option in the System tab for your virtual machine. Also, are you running Windows 7 in 64-bit mode? What about Ubuntu? Finally, what version of VBox are you running? Is it the proprietary version, or the open source version?

[sqcomic]

Windows 7 - 64 bit . . .
Ubuntu 9.10 - 64 bit . . .
My system has an AMD dual core with 4 G ram.
I've given the virtual machine 1 G, with 128 MB used for video.
I have AMD-V enabled, and giving the virtual machine access to both CPUs.

I monitor both the host and the virtual machine memory and CPU activity, neither are maxing out. The system works great when I start it up, then the response gets slow. Numerical calculations, etc, still work fine. But when I type in a terminal, it is very slow to update and show what I've typed. If I save the machine state, and then restart virtualbox without rebooting the host (just re-loading the state) the problem is fixed for a while.

[Rubberman]

Yes, but which version of VirtualBox are you running? And did you try running a 32-bit version of Ubuntu in the VM?

[sqcomic]

Sorry - I forgot to include that.
I am using the non-open-source version with usb support. I initially installed 3.1.2, but have upgraded several times - I'm currently using 3.1.8 r61349. I have had this same problem with every version of virtualbox I've tried.

No, I have not tried running the 32-bit version. I do some heavy numerical crunching sometimes, so I have exclusively used the 64-bit version.

[Rubberman]

Since you aren't using more than 1GB of RAM for your VM, then I would suggest that you run the 32-bit version. If you are making assumptions in your number crunching code that long integers are 64 bits, then you will need to change them to long long types. Other than that, you shouldn't see much, if any, difference in numeric processing speeds. I do know that Win7 support is fairly new to VBox, and I haven't tried running 64-bit clients in a VM, even though my host OS is a 64-bit version of Linux, CentOS/RHEL 5.

[sqcomic]

I do floating-point double precision calcs, which I believe take advantage of 64-bit processing. The memory usage never goes above 50% in normal use - so I don't think that not having enough memory allocated is the problem. Besides, it works when I reload the machine state - so it really sounds like a problem with virtualbox, not with the guest OS.

[Rubberman]

I agree that it is probably a vbox problem, however, the question is whether it's also a problem with its interaction w/ a 64-bit OS image. That is why I suggest you try the 32-bit binary. FWIW, your floating point should use the builtin FPU of the system processor which deals with 64-bit floating point values natively and in fact uses 80-bit registers internally. It is based upon the Intel 8087 FPU.

An aside - in case you're interested, the lead designer of that FPU was my old college buddy, Bruce Ravenel. His brother Doug was chairman (now Fayerweather Professor) of the math dept. at the University of Rochester. Two very smart people... If you are interested in their CV's, you can google them easily enough. I've known them well for about 45 years.