Reducing RHEL5 idle cpu usage under esx

Today I installed two RHEL5 servers on my ESXi rig. To my surprise they idled at around 300MHz?! My Debian 6.0 based server and my Win2k3 based server idles at around 50MHz, sowhat was the problem?!

Looking inside the vm showed that the vm was idle. So what was going on here? I tried to use vmxnet3 instead of E1000. I tried to stop a lot of services. To no avail.

It turns out that it is the frequency of the context switches. Edit /etc/grub.conf and add divider=10 to the ‘kernel’ line and reboot the beast. Usage will drop to sane levels!

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