Optimizing performance with large segment offload


New in Kerio Control 9.2.1!

Kerio Control includes large segment offload (LSO)A technique for increasing egress throughput of high-bandwidth network connections by reducing CPU overhead., also referred to as generic segmentation offload. LSO allows the network interface controller to process the segmentation of data transfers and significantly improves performance. However, these improvements are noticeable only during large data transfers, such as file downloads, or video streams.

LSO is supported on all Kerio Control NG hardware devices. Kerio Control virtual and software appliances support LSO only if your hardware supports it as well.

Configuring large segment offload

Verifying LSO support on Internet network adapters

LSO works only if you use network adapters that support LSO.

To verify that your network adapters support LSO, connect to Kerio Control via SSHSecure Shell - A cryptographic network protocol that enables you to connect securely over an unsecured network. and use the command ethtool:

  1. Connect to Kerio Control via SSH.
  2. Type ethtool -k xxxx | grep generic-segmentation, where xxxx represents your Internet interface, for example eth0 (the default value in Kerio Control).

If your Internet network adapter supports LSO, the result is

generic segmentation-offload: on

Disabling LSO in Kerio Control

In Kerio Control LSO is enabled by default. To disable LSO, connect to Kerio Control via SSH and update the tinydbclient configuration file:

  1. Connect to Kerio Control via SSH.
  2. Type /opt/kerio/winroute/tinydbclient "update Misc set PktOffloading=0"
  3. To apply the new configuration, restart Kerio Control with
/etc/boxinit.d/60winroute restart

After the restart, Kerio Control disables LSO.