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Patent Issued for Executing Virtual Functions Using Memory-Based Data in a PCI Express SR-IOV and MR-IOV Environment

June 25, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Ayzenfeld, Avraham (Tel Aviv, IL); Elder, Emmanuel (Haifa, IL); Granovsky, Ilya (Haifa, IL), filed on May 6, 2011, was published online on June 10, 2014.

The patent's assignee for patent number 8751713 is International Business Machines Corporation (Armonk, NY).

News editors obtained the following quote from the background information supplied by the inventors: "Peripheral Component Interconnect (PCI) Express is a standard for linking motherboard-mounted peripherals, and as an expansion card interface for add-in boards. Typically, PCI Express (PCIe) peripherals are auto configured via a PCI configuration space. In addition to the normal memory-mapped and I/O port spaces, each device on the PCIe bus has a configuration space.

"In a PCI Express system, a root complex device typically couples a processor and memory subsystem to a PCI Express switch fabric comprising one or more switch devices. The PCIe system also includes endpoints configured to perform and/or request PCI Express transactions. Each endpoint typically comprises one or more functions, and is mapped into the configuration space as a single function in a device that may include either the single function or multiple functions.

"PCI Express endpoints and legacy (i.e., PCI) endpoints typically appear within a hierarchical domain originated by the root complex. In other words, the endpoints appear in the configuration space as a tree with a root port as its head. Additionally, root complex integrated endpoints and root complex event collectors typically do not appear within one of the hierarchical domains originated by the root complex. Typically, the root complex integrated endpoints and root complex event collectors generally appear in the configuration space as peers of the root ports.

"Implementing virtualization can increase the effective hardware resource utilization of a PCI-Express device (i.e., the number of applications executing on the device). This approach has been addressed in the Single Root I/O Virtualization (SR-IOV) and Sharing Specification, Revision 1.0, Sep. 11, 2007, as well as in the Multi Root I/O Virtualization (MR-IOV) and Sharing Specification, revision 1.0, May 12, 2008, from the PCI Special Interest Group (SIG), whose disclosure is incorporated herein by reference. Both the SR-IOV and MR-IOV specifications define extensions to the PCIe specification, and enable multiple system images to share PCIe hardware resources. A system image comprises computer software such as operating systems, used to execute applications or trusted services, e.g., a shared or non-shared I/O device driver.

"SR-IOV and MR-IOV enable a PCIe device to appear to be multiple separate physical PCIe devices. In addition to functions, which comprise PCIe device configurations, SR-IOV and MR-IOV introduce the idea of physical functions and virtual functions, which can be used to enhance performance of the PCIe device.

"Physical functions are full-featured PCIe functions (per the PCI Express.RTM. Base Specification, Revision 3.0, Oct. 24, 2010, from PCI-SIG, whose disclosure is incorporated herein by reference) that support the SR-IOV capability and are accessible either to a single root PCI manager (which can be part of a multi root system), a virtual image, or a system image. In addition to having the capability to convey data 'in and out' of a PCIe device, physical functions typically have full configuration resources, thereby enabling them to configure or control the PCIe device via the physical functions.

"Virtual functions are 'lightweight' PCIe function that execute on a SR-IOV/MR-IOV endpoint, and are directly accessible by a system image. Each instance of a virtual function is associated with an underlying physical function and typically only has the ability to convey data in and out of the PCIe device.

"The SR-IOV capability (even when part of an MR-IOV design) typically reserves 16 bits for the number of virtual functions (i.e., NumVFs located at address 0x10 in the SR-IOV capability), meaning that the total number of virtual functions can theoretically reach 65,536 (i.e., 64K)."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "There is provided, in accordance with an embodiment of the present invention a method, including receiving, by an extended virtual function shell positioned on a Peripheral Component Interconnect Express (PCIe) configuration space, a virtual function call comprising a request to perform a specific computation, identifying a physical function associated with the called virtual function, the physical function one of multiple physical functions positioned on the PCIe configuration space, retrieving, from a virtual function instance stored in the memory, one or more first data values, the virtual function instance associated with the called virtual function, retrieving, from the identified physical function, one or more second data values, and performing the specific computation using the first data values and the second data values, thereby calculating a result.

"There is also provided, in accordance with an embodiment of the present invention an apparatus, including multiple physical functions positioned on a Peripheral Component Interconnect Express (PCIe) configuration space, a memory coupled to the PCIe configuration space, and an extended virtual function shell positioned on the PCIe configuration space and configured to receive a virtual function call comprising a request to perform a specific computation, to identify one of the physical functions associated with the specific virtual function, to retrieve, from a function instance associated with the specific virtual function and stored in the memory, one or more first data values, to retrieve, from the identified physical function, one or more second data values, and to perform the specific computation using the first data values and the second data values, thereby calculating a result."

For additional information on this patent, see: Ayzenfeld, Avraham; Elder, Emmanuel; Granovsky, Ilya. Executing Virtual Functions Using Memory-Based Data in a PCI Express SR-IOV and MR-IOV Environment. U.S. Patent Number 8751713, filed May 6, 2011, and published online on June 10, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8751713.PN.&OS=PN/8751713RS=PN/8751713

Keywords for this news article include: International Business Machines Corporation.

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Source: Journal of Engineering


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