feat(docs): Add Methodology

Signed-off-by: pmikus <peter.mikus@protonmail.ch>
Change-Id: I5b2e4c14cc258d821b630d2e54b23a8468820764

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+---
+bookToc: false
+title: "Generic Segmentation Offload"
+weight: 15
+---
+
+# 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 <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 -E -S ip netns exec tap1_namespace iperf3 \
+        --client 2.2.2.2 --bind 1.1.1.1 --port 5201 --parallel <Y> --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).
+
+
+## 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 <Y> --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).
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