High CPU utilization w/ Centos guest

I setup a VirtualBox Centos 5.3 guest for testing since I’m getting sick of KVM and it’s limited toolset. One thing I noticed is the guest was using around 100% of a core while idle. After some digging, I was able to find a solution, but it involved recompiling the kernel. In the kernel I made these changes:

Under Processor Type and Features:

Tickless System (Dynamic Ticks) = YES

Paravirtualized guest support = YES

Timer Frequency = 100 HZ

It’s possible I didn’t need to change all of these, but now idle utilization is down to 2% or less… a huge difference.

If you’re not familiar with compiling a kernel on a RHEL system, check out this guide.

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