To Enable TCP Packet Reassembly in the Driver

On the December 2005 release of 10 Gigabit Ethernet, the 10 Gigabit Ethernet driver significantly improves performance particularly at 1500MTU. The driver looks at the packets received, identifies those belonging to the same connection, performs re-assembly, and sends the re-assembled buffer to the upper layers. This reduces function calls across the network stack thereby reducing overhead on the receive CPU.

The performance gain that will be seen with this feature is workload dependent. Applications like backup would see good improvements; but other workloads may not see the same level of improvement.TCP Packet Reassembly in the Driver is disabled by default. You can enable this feature by either running a lanadmin command or setting a new parameter HP_IXGBE_SW_LRO in the /etc/rc.config.d/hpixgbeconf driver config file. When receive checksum offload is disabled, this feature gets disabled automatically. Trying to enable this feature when receive CKO is disabled will result in an error. To configure TCP Packet Reassembly in the Driver:

Set the new driver parameter HP_IXGBE_SW_LRO to ON or OFF in the driver config file /etc/rc.config.d/hpixgbeconf
Setting this field to ON enables this feature and setting it to OFF disables this feature when the driver startup script runs. The default setting of HP_IXGBE_SW_LRO is OFF.
To temporarily* enable this feature: lanadmin -X sw_lro_on ppa

To temporarily disable this feature: lanadmin -X sw_lro_off ppa

To query the status of this feature: lanadmin -x sw_lro ppa

(*lanadmin does not preserve your settings across reboots)
Note: On systems where the 10Gigabit Ethernet card is being used as a router, enabling this feature may have unintended side-effects and so the recommendation is to keep this feature disabled.

To Enable TCP Packet Reassembly in the Driver

Technical documentation

» Table of Contents