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Ubuntu 8.10 running in a Sun VirtualBox VM

Ubuntu 8.10 running in a Sun VirtualBox VM

Questions and Answers : Unix/Linux : Ubuntu 8.10 running in a Sun VirtualBox VM
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Profile Pete B

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Message 36504 - Posted: 27 Mar 2009, 11:00:46 UTC

I have set up Ubuntu 8.10 64bit running in a Sun VirtualBox virtual machine under Windows XP Pro x64 host OS on a Phenomx4 9950, 4Gb RAM PC. The VM has 1.5Gb of the RAM allocated to it. VM\'s can only \'see\' & use 1 processor, even under multiple core physical CPU\'s.

I am running 3 models in Windows in BOINC Client 6.2.19 64bit (1 HadCM3 160yr & 2 HadAM3P\'s), with 1 Linux HadSM3 5.10 running under Linux BOINC Client 6.4.5 64bit, a total of 1 model per core overall. Other than the well documented 32bit library issue with running 32bit applications in 64bit Linux BOINC clients, which I soon resolved, everything is running great apart from what seems a minor issue. The 3 Windows models report proper CPU time figures but the VM Linux model reports a time 4 times faster than normal, see here. It looks very impressive on the s/ts figure but the real CPU time is about 1.6 s/ts. It\'s as if a setting somewhere is causing the real CPU time to be divided by 4 giving the seemingly impressive timings at software level due to the only 1 CPU issue in VM.

I\'m new to VM\'s & Linux & I\'m not sure whether it\'s a VirtualBox or a \'BOINC in VM\' issue but I\'ve tried setting the specific PC settings in the Linux BOINC Client to either 25% of CPU time or 25% of processors when using multi processors to no avail. I can\'t see any other obvious settings in the Ubuntu system settings, VirtualBox or BOINC.

Any ideas?

Thanks.
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Belfry

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Message 36849 - Posted: 3 May 2009, 21:06:09 UTC - in response to Message 36504.  

I'm not sure if this could be the problem, but under VMware the guest CPU clock calibration can get messed up by frequency scaling of the host. Turn off the host's Cool 'n Quiet in BIOS, and turn off all power manangement programs on the host and guests.

Good luck.
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Profile Pete B

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Message 36866 - Posted: 6 May 2009, 15:11:21 UTC - in response to Message 36849.  
Last modified: 6 May 2009, 15:13:04 UTC

I'm not sure if this could be the problem, but under VMware the guest CPU clock calibration can get messed up by frequency scaling of the host. Turn off the host's Cool 'n Quiet in BIOS, and turn off all power manangement programs on the host and guests.

Good luck.


I'm certain you are correct in your deduction of the cause of the problem. Since I made the OP, I've done various tests and found effectively what you are saying. I never had the C&Q or any of the other CPU power management stuff enabled in the MoBo BIOS or the Windows host OS but nevertheless, the frequency scaling can become a problem and stop the normal time scaling of a VM operation.

If it happens, and it can sometimes happen during running of both host & virtual machines, say when a run completes, uploads and a new one starts on either machine, then the only way of getting back to correct timing is to shut down BOINC on both the real machine and the VM, shut down & reboot the VM, then start the VM BOINC Client before restarting the real BOINC Client. Strangely though, it doesn't always happen under these circumstances so it must depend on exactly what any running processes (BOINC or otherwise) are doing what on either machine at critical times. Messing around with the CPU allocations for either VM or real Clients in Windows 'Task Manager' has no effect on stopping the mistiming once it's happened.

Therefore, I see it as a VirtualBox issue rather than a Linux (the guest OS) one and one that may get resolved in a subsequent release, especially if & when VBox becomes capable of utilising more than one core of a multi core CPU.

Incidentally, I see that Windows 7 release will have µSoft's VirtualPC integrated into it for running XP legacy stuff - another lesson from Mac maybe ;-)
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Questions and Answers : Unix/Linux : Ubuntu 8.10 running in a Sun VirtualBox VM

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