System Administration Guide: Network Interfaces and Network Virtualization

ProcedureHow to Set the e1000g Driver to Use Direct Memory Access Binding

This procedure and the next procedure show how to configure private properties. Both procedures apply to properties specific to the e1000g driver. However, the general steps can be used to configure private properties of other NIC drivers as well.

Bulk traffic, such as file transfers, normally involves negotiation of large packets across the network. In such cases, you can obtain better performance from the e1000g driver by configuring it to automatically use DMA binding, where a threshold is defined for packet fragment sizes. If a fragment size surpasses the threshold, then DMA binding is used for transmitting. If a fragment size is within the threshold, then bcopy mode is used, where the fragment data is copied to the preallocated transmit buffer.

To set the threshold, perform the following steps:

  1. On the system that has the NIC whose properties you want to modify, assume the System Administrator role.

  2. Set the appropriate value for the _tx_bcopy_threshold property.

    # dladm set-linkprop -p _tx_bcopy_threshold=value e1000g-data-link

    For this property, the valid values for the threshold range from 60 through 2048.

    Note –

    As with configuring public properties, the interface must also be unplumbed before private property settings can be modified.

  3. (Optional) Verify the new threshold value.

    # dladm show-linkprop -p _tx_bcopy_threshold e1000g-data-link