Multiple CPUs in VirtualBox Guest still limited to one Host CPU core.

[dweimer]

I have been running VirtualBox in headless mode for a while on my home 
server.  Its just running a single VM with Windows 2011 HomeServer 
(windows 2008 R2 based) as a file server  I never did notice as there is 
very little CPU load that even though the guest is configured with 2 
CPUs the load is never on more than 1 core of the 6 core AMD processor.

I only noticed this after being happy with performance and stability of 
this setup, I migrated my laptop over to FreeBSD with VirtualBox to run 
Windows 8 in a VM, (yes I still have to run Windows for some things at 
work) however now that I am actually trying to do some interactive work 
in the VM I noticed it was a bit sluggish.  And this is when I 
discovered that the Intel Core i7 QUAD core CPU was cranking away on one 
core while the others were sitting idle.  I had configured the VM with 4 
CPUS to match those of the host, am I missing some setting?  Or is 
VirtualBox limited to one thread when running on a FreeBSD host.

FreeBSD is running 9.1p4 compiled from source using Clang with 
virtualbox-ose-4.2.16_2 installed from ports, with the following options 
set.

# This file is auto-generated by 'make config'.
# Options for virtualbox-ose-4.2.16_2
_OPTIONS_READ=virtualbox-ose-4.2.16_2
_FILE_COMPLETE_OPTIONS_LIST=DBUS DEBUG GUESTADDITIONS NLS PULSEAUDIO QT4 
UDPTUNNEL VDE VNC WEBSERVICE X11
OPTIONS_FILE_SET+=DBUS
OPTIONS_FILE_UNSET+=DEBUG
OPTIONS_FILE_SET+=GUESTADDITIONS
OPTIONS_FILE_SET+=NLS
OPTIONS_FILE_SET+=PULSEAUDIO
OPTIONS_FILE_SET+=QT4
OPTIONS_FILE_SET+=UDPTUNNEL
OPTIONS_FILE_UNSET+=VDE
OPTIONS_FILE_SET+=VNC
OPTIONS_FILE_UNSET+=WEBSERVICE
OPTIONS_FILE_SET+=X11

-- 
Thanks,
    Dean E. Weimer
    http://www.dweimer.net/