[spp] [PATCH 11/15] docs: add performance_opt section

[ogawa.yasufumi@lab.ntt.co.jp]

From: Yasufumi Ogawa <ogawa.yasufumi@lab.ntt.co.jp>

Add section for performance optimization containing following topics.

* Reduce context switches
* Optimizing QEMU performance

Signed-off-by: Yasufumi Ogawa <ogawa.yasufumi@lab.ntt.co.jp>
---
 docs/guides/setup/index.rst           |   1 +
 docs/guides/setup/performance_opt.rst | 106 ++++++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 docs/guides/setup/performance_opt.rst

diff --git a/docs/guides/setup/index.rst b/docs/guides/setup/index.rst
index 972132d..0ac18af 100644
--- a/docs/guides/setup/index.rst
+++ b/docs/guides/setup/index.rst
@@ -38,3 +38,4 @@ Setup Guide
    getting_started
    howto_use
    use_cases
+   performance_opt
diff --git a/docs/guides/setup/performance_opt.rst b/docs/guides/setup/performance_opt.rst
new file mode 100644
index 0000000..2bf8a5e
--- /dev/null
+++ b/docs/guides/setup/performance_opt.rst
@@ -0,0 +1,106 @@
+..  BSD LICENSE
+    Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+
+    * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+    * Neither the name of Intel Corporation nor the names of its
+    contributors may be used to endorse or promote products derived
+    from this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+Performance Optimization
+========================
+
+Reduce Context Switches
+-----------------------
+
+Use the ``isolcpus`` Linux kernel parameter to isolate them
+from Linux scheduler to reduce context switches.
+It prevents workloads of other processes than DPDK running on
+reserved cores with ``isolcpus`` parameter.
+
+For Ubuntu 16.04, define ``isolcpus`` in ``/etc/default/grub``.
+
+.. code-block:: console
+
+    GRUB_CMDLINE_LINUX_DEFAULT=“isolcpus=0-3,5,7”
+
+The value of this ``isolcpus`` depends on your environment and usage.
+This example reserves six cores(0,1,2,3,5,7).
+
+
+Optimizing QEMU Performance
+---------------------------
+
+QEMU process runs threads for vcpu emulation. It is effective strategy
+for pinning vcpu threads to decicated cores.
+
+To find vcpu threads, you use ``ps`` command to find PID of QEMU process
+and ``pstree`` command for threads launched from QEMU process.
+
+.. code-block:: console
+
+    $ ps ea
+       PID TTY      STAT   TIME COMMAND
+    192606 pts/11   Sl+    4:42 ./x86_64-softmmu/qemu-system-x86_64 -cpu host ...
+
+Run ``pstree`` with ``-p`` and this PID to find all threads launched from QEMU.
+
+.. code-block:: console
+
+    $ pstree -p 192606
+    qemu-system-x86(192606)--+--{qemu-system-x8}(192607)
+                             |--{qemu-system-x8}(192623)
+                             |--{qemu-system-x8}(192624)
+                             |--{qemu-system-x8}(192625)
+                             |--{qemu-system-x8}(192626)
+
+Update affinity by using ``taskset`` command to pin vcpu threads.
+The vcpu threads is listed from the second entry and later.
+In this example, assign PID 192623 to core 4, PID 192624 to core 5
+and so on.
+
+.. code-block:: console
+
+    $ sudo taskset -pc 4 192623
+    pid 192623's current affinity list: 0-31
+    pid 192623's new affinity list: 4
+    $ sudo taskset -pc 5 192624
+    pid 192624's current affinity list: 0-31
+    pid 192624's new affinity list: 5
+    $ sudo taskset -pc 6 192625
+    pid 192625's current affinity list: 0-31
+    pid 192625's new affinity list: 6
+    $ sudo taskset -pc 7 192626
+    pid 192626's current affinity list: 0-31
+    pid 192626's new affinity list: 7
+
+
+Reference
+---------
+
+* [1] `Best pinning strategy for latency/performance trade-off <https://www.redhat.com/archives/vfio-users/2017-February/msg00010.html>`_
+* [2] `PVP reference benchmark setup using testpmd <http://dpdk.org/doc/guides/howto/pvp_reference_benchmark.html>`_
+* [3] `Enabling Additional Functionality <http://dpdk.org/doc/guides/linux_gsg/enable_func.html>`_
+* [4] `How to get best performance with NICs on Intel platforms <http://dpdk.org/doc/guides/linux_gsg/nic_perf_intel_platform.html>`_
-- 
2.7.4