Configuring checksum offload operations
Some operations can be offloaded to the OSA adapter, thus relieving the burden on the host CPU. The qeth device driver supports checksum offloading for TCP and UDP network packets.
The qeth device driver supports offloading the following checksum
operations on both layer 2 and layer 3:
- Inbound (receive) checksum calculations
- Outbound (send) checksum calculations
The qeth device driver also supports offloading TSO segmentation, see Enabling and disabling TCP segmentation offload.
VLAN interfaces inherit offload settings from their base interface.
The offload operations can be set with the Linux
ethtool command, version 6 or later. See the ethtool man page
for details. The following abbreviated example shows some offload settings:
# ethtool -k eth0 Features for eth0: rx-checksumming: on tx-checksumming: on tx-checksum-ipv4: on tx-checksum-ip-generic: off [fixed] tx-checksum-ipv6: off [fixed] tx-checksum-fcoe-crc: off [fixed] tx-checksum-sctp: off [fixed] scatter-gather: on tx-scatter-gather: on tx-scatter-gather-fraglist: off [fixed] tcp-segmentation-offload: on tx-tcp-segmentation: on tx-tcp-ecn-segmentation: off [fixed] tx-tcp6-segmentation: off [fixed] udp-fragmentation-offload: off [fixed] generic-segmentation-offload: off [requested on] generic-receive-offload: on large-receive-offload: off [fixed] ...