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  • About

    This blog is all about PCI Express: the wonderful ways that it enhances the products around you, the challenges designers face in implementation, and how the specification is evolving to make PCIe Express an even more useful protocol. I'll also examine how the other specifications, such as NVM Express, SATA Express and SCSI-Over-PCI Express (SOP) are leveraging PCI Express. If there is a topic that is of interest to you, feel free to "Express Yourself" by offering your insights on this blog.
  • About the Author

    Scott Knowlton

    I started out my career as a chip designer in a variety of industries and it’s likely that a few, of the more than 30 designs I’ve been responsible for, are still floating around somewhere in outer space. My IP career started at Synopsys in 1997 and over the last 15 years, I have seen tremendous changes in the semiconductor industry’s perception and adoption of IP. I started working on PCI Express in 2003 when Synopsys was getting ready to launch our first PCI Express IP solution. Since then, I have been managing the DesignWare PCI Express IP product line through all of the changes in the specification and the industry as it moves towards becoming the de-facto interconnect standard. I received a B.S.E.E from the University of Michigan (M Go Blue!), am an avid red wine drinker (love California reds) and use English as a second language when my fluency in sarcasm just doesn’t get the job done.

    Richard Solomon

    I’ve been involved in the development of PCI chips dating back to the NCR 53C810 and pre-1.0 versions of the PCI spec so have definitely lived the evolution of PCI Express and PCI since the very beginning! Over the years I have worked on variations of PCI, eventually moving on to architecting and leading the development of the PCI Express and PCI-X interface cores used in LSI’s line of storage RAID controller chips. For the last ten plus years I've also had the honor of serving on the PCI-SIG Board of Directors and holding a variety of officer positions. I am still involved in PCI-SIG workgroups and I present at many PCI-SIG events around the world. Back before the dawn of PCI, I received my B.S.E.E. from Rice University, and hold over two dozen U.S. Patents, many of which relate to PCI technology.

PCI Express w/SR-IOV – It’s Virtually Awesome

Posted by Scott Knowlton on December 16th, 2012

Virtualization technology essentially componentizes a computer system into the following:

  • Physical System: The computer hardware, e.g. processors, disk drives, memory, etc.
  • Virtualization Intermediary (VI): The VI abstracts the details of the physical resources, isolates them and then maps them into virtual resources, while managing their allocation in the system. Since the VI is creating and managing the virtual resources, it can create multiple virtual resources for each of the physical resources, while providing isolation between them.
  • Virtual System: The set of virtual resources required to run a system image is referred to as a Virtual System. 
  • System Image (SI): The software component consisting of the operating system and applications that are assigned to run on a specific virtual resource. The system image only needs to know the details of the Virtual System they are assigned to.

PCI Express with Single Root I/O Virtualization (SR-IOV) enables some of the virtualization to be done in hardware for the I/O devices instead of software, thereby streamlining the Virtualization Intermediary. Of course, hardware runs faster than software for the same function, so PCI Express with SR-IOV helps improve the overall system performance of a virtualized system.

To understand the benefits of PCI Express with SR-IOV, you can watch SolarFlare’s demo that was videotaped in the Synopsys booth at the Intel Developer’s Forum (IDF) conference in 2011 (shown below).  The demo utilizes two servers running Citrix XenServer 6 to showcase the 3x in performance achieved when utilizing PCI Express 2.0 with SR-IOV virtualization technology. By incorporating DesignWare PCIe IP with SR-IOV, SolarFlare’s Dual Port SFP+ 10GbE Server Adapters were able to support hundreds of virtual PCIe functions and thousands of virtual NICs, thus reducing total hardware costs and power consumption, while increasing performance.

It’s tough to explain such complex technology in a blog posting, but in a nutshell, PCI Express with SR-IOV enables virtualization of a single physical I/O device to masquerade as multiple virtualized I/O devices, one for each virtual machine and with complete independence from each other.  You can learn more about how virtualization benefits PCI Express by reading this whitepaper:


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