TCP Segmentation Offload

TCP segmentation offload (TSO) enables the adapter cards to accept a large amount of data with a size greater than the MTU size. The TSO engine splits the data into separate packets and inserts the user-specified L2/L3/L4 headers automatically per packet. With the usage of TSO, CPU is offloaded from dealing with a large throughput of data.

TSO Experimental vs. RDMA-Core Verbs and Capabilities

Experimental Verbs		RDMA-Core
Verbs
`ibv_exp_create_qp`		`ibv_create_qp_ex`
`ibv_exp_create_qp`	`max_tso_header`	`ibv_create_qp_ex`	`max_tso_header`
`ibv_exp_query_device`		`ibv_query_device_ex`
`ibv_exp_query_device`	`tso_caps`	`ibv_query_device_ex`	`tso_caps`
`ibv_exp_post_send`	`tso`	`ibv_post_send` `ibv_wr_send_tso`	`tso`
Capabilities and Device Attributes
`IBV_EXP_DEVICE_ATTR_TSO_CAPS`

Relevant Man Pages

ibv_create_qp_ex
ibv_query_device_ex

Last updated: June 26, 2026