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? Thanks, Sagi