[CentOS-virt] High CPU usage when running a CentOS guestinVirtualBox
Hildebrand, Nils, 232
Nils.Hildebrand at bamf.bund.de
Mon Sep 14 15:24:24 UTC 2009
KVM uses a para-virtualized approach?
With para-virtualized guests or with 32-bit guests running a single CPU
there is no need to simulate the IO-APIC.
> -----Original Message-----
> From: centos-virt-bounces at centos.org
> [mailto:centos-virt-bounces at centos.org] On Behalf Of Akemi Yagi
> Sent: Tuesday, September 01, 2009 6:15 PM
> To: Discussion about the virtualization on CentOS
> Subject: Re: [CentOS-virt] High CPU usage when running a
> CentOS guestinVirtualBox
> On Tue, Sep 1, 2009 at 5:33 AM, Hildebrand, Nils,
> 232<Nils.Hildebrand at bamf.bund.de> wrote:
> > 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
> > - 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.
> Interesting. I do not have any 32-bit multi-cpu VMs myself,
> but I do have access to such guests running on a host
> (64-bit) using kvm. Both
> CentOS-5 32-bit VM and CentOS-4 32-bit VM show normal load
> (near 100% idle on all cpus). They have the divider=10
> option by the way.
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