[CentOS-virt] High CPU usage when running a CentOS guest in VirtualBox

Mon Jul 6 17:22:25 UTC 2009
Sagi Bashari <sagi at boom.org.il>

On Mon, Jul 6, 2009 at 6:44 PM, Akemi Yagi<amyagi at gmail.com> wrote:
> On Mon, Jul 6, 2009 at 8:31 AM, Sagi Bashari<sagi at boom.org.il> wrote:
>> Hi,
>> I am running CentOS 5.3 32bit as a VirtualBox 3.0.0 guest running on Windows XP.
>> The Windows host CPU usage is constantly at 50% although the CentOS
>> guest is completely idle (i.e. 0.00 load average).
>> I know this is a common problem related to the 1000Hz frequency that
>> the CentOS kernel runs at. With previous versions of CentOS, I used
>> the kernel-vm package [1] and it solved my problem. However, according
>> to the README [2] this isn't necessary as of CentOS 5.3 and therefore
>> these packages are not maintained anymore (the latest released
>> kernel-vm is 2.6.18-92.1.22).
>> >From what I understand, as of CentOS 5.3 it is possible to use the
>> "divider=10 clocksource=acpi_pm" to reduce the frequency to 100Hz. I
>> tried this setting, and it made no difference at all.
> This is interesting.  Could you please try installing the regular
> 2.6.18-92.1.22 kernel and use the "divider=10 clocksource=acpi_pm"
> option?  This is the only way to compare the kernel-vm and the distro
> kernel.  Currently, the difference you are seeing could be due to the
> fact kernel-vm was from 5.2 and the distro one was from 5.3.

Actually, it looks like I got it wrong. I was too quick to draw these
conclusions: My previous experience with the kernel-vm package was on
a different host, with a different version of VirtualBox (2.2.2), on a
different host operating system (Windows 2003 Server). There, I
encountered the same problem of high CPU usage and installing the
kernel-vm problem indeed solved it. But now I went back to the same
host and installed the latest CentOS 5.3 kernel (2.6.18-128.1.16.el5)
and idle CPU usage was low without using any special parameters.

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?