Inside the Briefcase
The Late Great Virtual CPU Debate
June 9, 2011 No CommentsBlog post by Ken Hess
Do you ever have the situation where you have a sluggish virtual machine (VM) and in trying to find the bottleneck, you raise the number of vCPUs? Did it work? If your VM experiences a slowdown, then the problem is the extra vCPU(s). It’s counterintuitive to see this occur but it’s a real phenomenon. To clarify, you might experience a performance hit by adding vCPUs to a VM. Crazy, yes, but there are some good reasons for it.
You also want to be careful of using multiple vCPUs and then moving back to a single vCPU. Some operating systems don’t do well with that change. Windows Server 2003 being one of them.
