Hi, I just closed a service-request with sun. Topic: Why is Win32 slower running with two CPUs under VBox 3 than running with one CPU on VBox 2? I am running VBox on CentOS 5 64 bit (AMD Athlon Dual Core). The problem is - according to sun - the IO-APIC-emulation: On 32-bit-systems this io-apic-emulation (needed for passing interrupts between CPUs) has to use a full software-context-switching - making things slow. I tried recreating the problem with CentOS 5 64 Bit as VM, two CPUs: no problem With CentOS 5 32 Bit as VM: same problem. I guess some problems with multi-cpu-VMs using 32-bit-operating-systems on a 64-bit hardware are related to this - no matter if you are using xen (fully virtualized), VirtualBox or VMWare. Kind regards Nils > -----Original Message----- > From: centos-virt-bounces at centos.org > [mailto:centos-virt-bounces at centos.org] On Behalf Of Akemi Yagi > Sent: Monday, July 06, 2009 10:24 PM > To: Discussion about the virtualization on CentOS > Subject: Re: [CentOS-virt] High CPU usage when running a > CentOS guest inVirtualBox > > On Mon, Jul 6, 2009 at 10:22 AM, Sagi Bashari<sagi at boom.org.il> wrote: > > > On my new box where I currently encounter the problem I tried > > installing the regular 2.6.18-92.1.22 kernel with the "divider=10 > > clocksource=acpi_pm" parameters like you suggested, and > also the old > > kernel-vm package, and in both of these attempts idle host > CPU usage > > was at 50%. So it looks like although the symptoms are the same the > > cause is different. > > > > I guess it may be related to the newer version of VirtualHost, the > > different hardware or the different operating system. Any idea what > > else I can try to reduce the CPU usage on this host? > > Because the issue is most likely related to VirtualBox and > Windows rather than CentOS, you may have a better chance of > getting help by going to the VB channels: > > http://www.virtualbox.org/wiki/Community > > Akemi > _______________________________________________ > CentOS-virt mailing list > CentOS-virt at centos.org > http://lists.centos.org/mailman/listinfo/centos-virt >