CSIT-1420: Split methodology section to more files

[csit.git] / docs / report / introduction / methodology_multi_core_speedup.rst

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+Multi-Core Speedup
+------------------
+
+All performance tests are executed with single processor core and with
+multiple cores scenarios.
+
+Intel Hyper-Threading (HT)
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Intel Xeon processors used in FD.io CSIT can operate either in HT
+Disabled mode (single logical core per each physical core) or in HT
+Enabled mode (two logical cores per each physical core). HT setting is
+applied in BIOS and requires server SUT reload for it to take effect,
+making it impractical for continuous changes of HT mode of operation.
+
+|csit-release| performance tests are executed with server SUTs' Intel
+XEON processors configured with Intel Hyper-Threading Disabled for all
+Xeon Haswell testbeds (3n-hsw) and with Intel Hyper-Threading Enabled
+for all Xeon Skylake testbeds.
+
+More information about physical testbeds is provided in
+:ref:`tested_physical_topologies`.
+
+Multi-core Tests
+~~~~~~~~~~~~~~~~
+
+|csit-release| multi-core tests are executed in the following VPP worker
+thread and physical core configurations:
+
+#. Intel Xeon Haswell testbeds (3n-hsw) with Intel HT disabled
+   (1 logical CPU core per each physical core):
+
+  #. 1t1c - 1 VPP worker thread on 1 physical core.
+  #. 2t2c - 2 VPP worker threads on 2 physical cores.
+  #. 4t4c - 4 VPP worker threads on 4 physical cores.
+
+#. Intel Xeon Skylake testbeds (2n-skx, 3n-skx) with Intel HT enabled
+   (2 logical CPU cores per each physical core):
+
+  #. 2t1c - 2 VPP worker threads on 1 physical core.
+  #. 4t2c - 4 VPP worker threads on 2 physical cores.
+  #. 8t4c - 8 VPP worker threads on 4 physical cores.
+
+VPP worker threads are the data plane threads running on isolated
+logical cores. With Intel HT enabled VPP workers are placed as sibling
+threads on each used physical core. VPP control threads (main, stats)
+are running on a separate non-isolated core together with other Linux
+processes.
+
+In all CSIT tests care is taken to ensure that each VPP worker handles
+the same amount of received packet load and does the same amount of
+packet processing work. This is achieved by evenly distributing per
+interface type (e.g. physical, virtual) receive queues over VPP workers
+using default VPP round- robin mapping and by loading these queues with
+the same amount of packet flows.
+
+If number of VPP workers is higher than number of physical or virtual
+interfaces, multiple receive queues are configured on each interface.
+NIC Receive Side Scaling (RSS) for physical interfaces and multi-queue
+for virtual interfaces are used for this purpose.
+
+Section :ref:`throughput_speedup_multi_core` includes a set of graphs
+illustrating packet throughout speedup when running VPP worker threads
+on multiple cores. Note that in quite a few test cases running VPP
+workers on 2 or 4 physical cores hits the I/O bandwidth or packets-per-
+second limit of tested NIC.