You can create OpenStack instances using DirectPath I/O and Single Root I/O Virtualization (SR-IOV) passthrough devices.

Passthrough assigns a physical device with a virtual machine, reducing the latency associated with virtualization. The following table shows how passthrough is implemented in VMware Integrated OpenStack.

Table 1. Key Passthrough Components and Roles

Component

Role

Nova compute

  • Collects the list of SR-IOV devices and updates the list of PCI device specifications.

  • Embeds the host object ID in device specifications.

Nova PCI manager

  • Creates and maintains a device pool with address, vendor ID, product ID, and host ID.

  • Allocates and deallocates PCI devices to instances based on PCI requests.

Nova scheduler

  • Schedules instance placement on hosts that matches the PCI requests

vSphere

  • Manages hosts in a dedicated compute cluster with NICs and hosts enabled for SR-IOV.

    A separate compute cluster is recommended because DRS rules do not work on devices enabled for SR-IOV.