Whitepaper: Performance of AMD Rapid Virtualization Indexing (RVI)

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In September 2007 AMD was the first on the market to introduce an implementation of the much awaited nested page tables technology that promises unprecedented performance for virtualization platforms: the Rapid Virtualization Indexing (RVI).

As every virtualization professional knows, even the most enhanced CPU extension it’s useless without a virtualization vendor that supports it in its hypervisor.
VMware introduced support for AMD-V RVI almost one year ago with the release of VI 3.5.

Today most hypervisors support it (to see which ones you may want to check the brand new virtualization.info Buyer’s Guide) but we still didn’t have much details about the performance boost that this technology provides in a virtual infrastructure.

This week VMware released a very interesting 9-pages whitepaper answering the question:

…We evaluated RVI performance by comparing it to the performance of our software-only shadow page table technique on an RVI-enabled AMD system. From our studies we conclude that RVI-enabled systems can improve performance compared to using shadow paging for MMU virtualization.

RVI provides performance gains of up to 42% for MMU-intensive benchmarks and up to 500% for MMU-intensive microbenchmarks

These results come out of an analysis conducted with VMware ESX 3.5 Update 2 and the upcoming AMD Quad-Core Opteron 8384 (codename Shanghai).

While waiting for the Intel version of this technology, dubbed Extended Page Tables (EPT) and expected somewhere between 2009 and 2010, this paper is a great reading.