--- title: "Generic Segmentation Offload" weight: 7 --- # Generic Segmentation Offload ## Overview Generic Segmentation Offload (GSO) reduces per-packet processing overhead by enabling applications to pass a multi-packet buffer to (v)NIC and process a smaller number of large packets (e.g. frame size of 64 KB), instead of processing higher numbers of small packets (e.g. frame size of 1500 B), thus reducing per-packet overhead. GSO tests for VPP vhostuser and tapv2 interfaces. All tests cases use iPerf3 client and server applications running TCP/IP as a traffic generator. For performance comparison the same tests are run without GSO enabled. ## GSO Test Topologies Two VPP GSO test topologies are implemented: 1. iPerfC_GSOvirtio_LinuxVM --- GSOvhost_VPP_GSOvhost --- iPerfS_GSOvirtio_LinuxVM - Tests VPP GSO on vhostuser interfaces and interaction with Linux virtio with GSO enabled. 2. iPerfC_GSOtap_LinuxNspace --- GSOtapv2_VPP_GSOtapv2 --- iPerfS_GSOtap_LinuxNspace - Tests VPP GSO on tapv2 interfaces and interaction with Linux tap with GSO enabled. Common configuration: - iPerfC (client) and iPerfS (server) run in TCP/IP mode without upper bandwidth limit. - Trial duration is set to 30 sec. - iPerfC, iPerfS and VPP run in the single SUT node. ## VPP GSOtap Topology ### VPP Configuration VPP GSOtap tests are executed without using hyperthreading. VPP worker runs on a single core. Multi-core tests are not executed. Each interface belongs to separate namespace. Following core pinning scheme is used: - 1t1c (rxq=1, rx_qsz=4096, tx_qsz=4096) - system isolated: 0,28,56,84 - vpp mt: 1 - vpp wt: 2 - vhost: 3-5 - iperf-s: 6 - iperf-c: 7 ### iPerf3 Server Configuration iPerf3 version used 3.7 $ sudo -E -S ip netns exec tap1_namespace iperf3 \ --server --daemon --pidfile /tmp/iperf3_server.pid \ --logfile /tmp/iperf3.log --port 5201 --affinity For the full iPerf3 reference please see [iPerf3 docs](https://github.com/esnet/iperf/blob/master/docs/invoking.rst). ### iPerf3 Client Configuration iPerf3 version used 3.7 $ sudo -E -S ip netns exec tap1_namespace iperf3 \ --client 2.2.2.2 --bind 1.1.1.1 --port 5201 --parallel \ --time 30.0 --affinity --zerocopy For the full iPerf3 reference please see [iPerf3 docs](https://github.com/esnet/iperf/blob/master/docs/invoking.rst). ## VPP GSOvhost Topology ### VPP Configuration VPP GSOvhost tests are executed without using hyperthreading. VPP worker runs on a single core. Multi-core tests are not executed. Following core pinning scheme is used: - 1t1c (rxq=1, rx_qsz=1024, tx_qsz=1024) - system isolated: 0,28,56,84 - vpp mt: 1 - vpp wt: 2 - vm-iperf-s: 3,4,5,6,7 - vm-iperf-c: 8,9,10,11,12 - iperf-s: 1 - iperf-c: 1 ### iPerf3 Server Configuration iPerf3 version used 3.7 $ sudo iperf3 \ --server --daemon --pidfile /tmp/iperf3_server.pid \ --logfile /tmp/iperf3.log --port 5201 --affinity X For the full iPerf3 reference please see [iPerf3 docs](https://github.com/esnet/iperf/blob/master/docs/invoking.rst). ### iPerf3 Client Configuration iPerf3 version used 3.7 $ sudo iperf3 \ --client 2.2.2.2 --bind 1.1.1.1 --port 5201 --parallel \ --time 30.0 --affinity X --zerocopy For the full iPerf3 reference please see [iPerf3 docs](https://github.com/esnet/iperf/blob/master/docs/invoking.rst).