VMware server on linux CentOS taking high kernel usage when guest is running


A bit more background info:
We've installed a webserver system that is a plain AMD system with 4Gb memory and a 3ware controller. It needs to run one production webserver for some basic hosting. But in order to restore and keep a bit of security, we've installed VMWare server on the host on top a CentOS Linux and installed the webserver in a i386 linux guest VM.

Our problem:
If we powerup the VM guest, kernel usage raises sometimes to 200% (= both cores fully loaded of the host CPU). Inside the guest VM's, cpu usage is 0%, runs actually idle.

On the host, Load averages range from 1.4 to 1.6 when the guest is running. No swap is in use and 1,5Gb memory is free. I also tried to install a second VM for some testing (basic OS, nothing else). This gives the same problem.

Output of the top command shows it are always the vmware-vmx processes of the guests that take all %sys usage (= kernel) of the host. Powering down the guest leaves the host in idle state with 0% cpu usage. For more info, refer to the screenshot in attach.

Could this be a flaw in the compiled modules VMware uses?

Host OS: CentOS 5.5 x86_64
Host Architecture: AMD dual Core 4400+ / 4Gb DDR2
Host Installed storage: 3ware 9650SE-2LP - Hardware RAID 1 (2x 250Gb disks)
Software: VMware Server 1.0.4., rpm, i386 installed
Kernel: vanilla CentOS kernel-2.6.18-53.el5.x86_64
Used guest OS'es: CentOS 5.5 i386 & Centos x86_64

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techneitsolutionsConnect With a Mentor Author Commented:
Installation of a Fedora 8 for testing soved it. Seems it was the centos kernel in combination with vmware compiling it's own modules to load into the kernel.

Do you have vmware tools installed on the guest?  That might help.
techneitsolutionsAuthor Commented:
No i dont, but i'm sure it has nothing to do with the vmware tools.

On a second proliant system, poweron the same VM results in max 10% cpu load (user mode) if the VM guest is idle.

The AMD machine really has a problem with kernel usage and VMware.

Difference in host machines is the proliant has a i386 OS installed, the AMD a x86_64. Maybe a 64 bit os isn't that compatible with vmware's modules.

Also, the reason why i didn't installed the VMware tools is that it corrupts the virtual network interface inside the centos VM guest.
This is the first that I have heard that VMware tools coorupts the vNIC in Linux, infact it gives the OS a nic that is more effecitent as It changes the driver from vlance driver to vmxnet.

Could you explain a bit more what you found with the centos kernel?
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