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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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.
techneitsolutionsAuthor 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.


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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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