Passthrough devices provide the means to more efficiently use resources and improve performance in your environment. You can configure a passthrough PCI device on a virtual machine in the vSphere Web Client.

When using passthrough devices with a Linux kernel version 2.6.20 or earlier, avoid MSI and MSI-X modes because these modes have significant performance impact.


Verify that a passthrough networking device is configured on the host of the virtual machine. See Enable Passthrough for a Network Device on a Host.


  1. Locate the virtual machine in the vSphere Web Client.
    1. Select a data center, folder, cluster, resource pool, or host and click the VMs tab.
    2. Click Virtual Machines and double-click the virtual machine from the list.
  2. Power off the virtual machine.
  3. On the Configure tab of the virtual machine, expand Settings and select VM Hardware.
  4. Click Edit and select the Virtual Hardware tab in the dialog box displaying the settings.
  5. Expand the Memory section, and set the Limit to Unlimited.
  6. From the New device drop-down menu select PCI Device and click Add.
  7. From the New PCI device drop-down menu select the passthrough device to use, and click OK.
  8. Power on the virtual machine.


Adding a DirectPath I/O device to a virtual machine sets memory reservation to the memory size of the virtual machine.