[Novalug] Virtual box cpu usage

Jon LaBadie novalugml@jgcomp.com
Sat Dec 13 08:59:34 EST 2008


On Fri, Dec 12, 2008 at 09:27:26AM -0500, The Doctor wrote:
> Jon LaBadie wrote:
> > Under Fedora 9 I have VirtualBox running
> > a winXP pro session.  I have few bkg procs
> > running on winXP.  If I'm not doing any
> > windows tasks the task manager shows V low
> > cpu usage.  Yet in this "idle state", top on
> > Fedora 9 shows VBox is using 30-35% of one 
> > core of my system.
> > 
> > This is my first experience with VBox.  Is
> > this type of idle cpu usage typical?
> 
> It seems a little odd.  I've been using VirtualBox for a couple of
> months to test it out, and I've noticed that it tends to bounce between
> 4% and 19% of CPU utilization if you let the guest OS run on its own
> (Windows XP SP2).
> 
> How much RAM do you have in your box?  How many CPUs, and of what kind?
>  What revision of VirtualBox are you running?
> 
> Jon LaBadie wrote:
> 
> > System is dual core AMD 5600 with 4GB of RAM. 
> > Running the PAE version of Fedora 9 so I see all 4GB.
> > VBox version is 2.06.
> 
> <whistles>
> 
> This is strange, indeed.  I'm running VirtualBox v2.0.4 on a dual-core
> laptop (Intel T7500 (2.2 GHz)) with 2GB of RAM on top of Gentoo 2008.0
> (kernel revision 2.6.27.4).
> 

Turns out it was an example of the Heisenberg uncertainty principle
(or Schrodinger's cat if you prefer :) where the experimental tools
were affecting the results.

My primary measurement tool was the graphical gnome-system-monitor.
Turns out this consumes substantial Xorg cpu cycles for its updates.

I compiled an alternative (sdtperfmeter and rstatd) from the
Solaris world and sure enough there is little total cpu usage
when both native Fedora and the virtual winXP are idle.

Jon
-- 
Jon H. LaBadie                  jon@jgcomp.com
 JG Computing
 12027 Creekbend Drive		(703) 787-0884
 Reston, VA  20194		(703) 787-0922 (fax)



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