Oracle® VM Server for SPARC 3.3 Administration Guide

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Updated: October 2015

General Guidelines for Creating an I/O Domain

An I/O domain might have direct access to one or more I/O devices, such as PCIe buses, network interface units (NIUs), PCIe endpoint devices, and PCIe single root I/O virtualization (SR-IOV) virtual functions.

    This type of direct access to I/O devices means that more I/O bandwidth is available to provide the following:

  • Services to the applications in the I/O domain

  • Virtual I/O services to guest domains

    The following basic guidelines enable you to effectively use the I/O bandwidth:

  • Assign CPU resources at the granularity of CPU cores. Assign one or more CPU cores based on the type of I/O device and the number of I/O devices in the I/O domain.

    For example, a 1-Gbps Ethernet device might require fewer CPU cores to use the full bandwidth compared to a 10-Gbps Ethernet device.

  • Abide by memory requirements. Memory requirements depend on the type of I/O device that is assigned to the domain. A minimum of 4 Gbytes is recommended per I/O device. The more I/O devices you assign, the more memory you must allocate.

  • When you use the PCIe SR-IOV feature, follow the same guidelines for each SR-IOV virtual function that you would use for other I/O devices. So, assign one or more CPU cores and memory (in Gbytes) to fully use the bandwidth that is available from the virtual function.

Note that creating and assigning a large number of virtual functions to a domain that does not have sufficient CPU and memory resources is unlikely to produce an optimal configuration.

SPARC systems, up to and including the SPARC T5 and SPARC M6 platforms, provide a finite number of interrupts, so Oracle Solaris limits the number of interrupts that each device can use. The default limit should match the needs of a typical system configuration but you might need to adjust this value for certain system configurations. For more information, see Adjusting the Interrupt Limit.