The VMguy

Most people are going to read that title and say, "Dave, what is RVI and why do I care?"

Here’s why: When a virtual machine is running, inside the VM, the operating system maps out pages of RAM.  The hypervisor then addresses and stores those pages in physical RAM.  The address in physical RAM typically never matches the address that the VM’s operating system knows.  The hypervisor (specifically the virtual machine monitor or VMM) has to "translate" the fetching and updating of pages of RAM.  This puts an extra "tax" on the CPU and adds to virtualization overhead.  This can specifically be seen in workloads that perform very frequent page table updates. Read the rest of this entry »