What is SR-IOV and Why Is it the Gold-Standard for GPU Sharing?

In virtualization, SR-IOV (Single Root Input/Output Virtualization) is a specification that allows the isolation of PCI Express resources between different users. It is already the standard used to share networking resources (NICs) and secure network traffic. Each resource has Virtual Functions (VF) associated and each VM (Virtual machine) can only access the physical resource via its own allocated VF.

The AMD MxGPU (GPU sharing technology) is the industry’s first SR-IOV-based GPU sharing technology designed for cloud and datacenter. So why did we choose SR-IOV?

• Industry standard. SR-IOV is the long-established industry standard for virtualizing PCIE devices. As such, the standards are openly scrutinized for security.
• The isolation provided by VFs helps ensure each VM is isolated from other –memory is secured and not shared.
• Scalability. Long-term we believe SR-IOV is a base technology that will allow for scalability and higher-user densities long term as a technology that minimizes context-switching overheads.
• Stability and reliability. SR-IOV allows us to provide each VM with its own dedicated share of a GPU and it does not compete with other users, helping ensure the resource available is consistent and the same. In other words, users can avoid the unreliability associated with noisy neighbours and experience deterministic QoS.

SR-IOV a technology that has evolved with and for cloud

Back in 2009. veteran blogger Scott Lowe wrote an introduction to SR-IOV predicting it would become mainstream, it’s great context to the environment and technology of the time. While we could have accelerated to market using a bespoke proprietary memory management unit (MMU), we instead chose to work with the major hardware, hypervisor and operating system vendors to evolve the technologies to an industry wide fit for our long-term needs.

The evolution of SR-IOV was carefully managed and, in 2016, was able AMD to release the world’s first SR-IOV based GPU sharing solution for cloud and virtualisation. Beyond the obvious security and quality benefits of aligning to the core technology, the standards offer potential long-term scalability that a bespoke implementation wouldn’t have offered us.

We are seeing increasing rewards from this approach now, as other vendors – particularly Microsoft – have placed SR-IOV at the core of their technologies and infrastructure. This alignment has streamlined our joint projects, leading to the announcement of MXGPU into the Azure cloud to enable cost-effectively sized and priced GPU enabled VMs. (You can register interest with Microsoft in the release availability.) MxGPU SR-IOV support is also available and proven for Citrix XenServer, XenDesktop and XenApp, VMware ESXi, Horizon View and open source KVM. Read more, here.

SR-IOV and MXGPU at Ignite

Our product management team will be at Microsoft Ignite (November 4-8) – you can find us in booth #249. You might also like to join these AMD sessions: technical session BRK1114 (Friday, Nov 8, 9am) and hub session THR1086 (Tuesday, Nov 5, 9am), if you’re lucky enough to be there in person.

Learn More

• Microsoft’s high commitment and investment in integrating the SR-IOV standards into the core of their platforms such as Windows and Hyper-V is significant. As such, they’ve published significant information on this approach including overviews and architectural deep-dives.
• Our hypervisor and virtualization partners have also been investing in core SR-IOV technologies, as well as releasing information as to the benefits and reasons for this approach. In September 2018, Citrix released XenServer 7.6; the release notes are available to read, among other features they cover Citrix’s and XenServer’s adoption of SR-IOV for networking (NICs – Network Interface Cards).

The SR-IOV standard

The SR-IOV standard is controlled and maintained by the PCI-SIG foundation. The regulation and scrutiny of the standard is maintained with cross-industry membership and funding, alongside a compliance programme and certified integrator list.

MXGPU more than SR-IOV

Of course, there is more to MXGPU than SR-IOV, it is just one of core technologies on top of which we have built our GPU sharing and virtualisation products. We are pleased, however, that we were the first vendor to achieve GPU sharing via the SR-IOV “gold-standard.”