doc: Instruction of enabling ACRN-DM QoS.

Add instruction of enabling ACRN-DM QoS based on runC container.

Tracked-On: #3131
Signed-off-by: ruix.li <ruix.li@intel.com>

Author: lirui34

doc/tutorials/acrn-dm_QoS.rst

@@ -0,0 +1,119 @@
+.. _acrn-dm_qos:
+
+Enable QoS based on runC container
+##################################
+This document describes how ACRN supports Device-Model Quality of Service (QoS)
+based on using runC containers to control the SOS resources
+(CPU, Storage, Memory, Network) by modifying the runC configuration file.
+
+What is QoS
+***********
+Traditionally, Quality of Service (QoS) is the description or measurement
+of the overall performance of a service, such as a `computer network
+<https://en.wikipedia.org/wiki/Computer_network>`_ or a `cloud computing
+<https://en.wikipedia.org/wiki/Cloud_computing>`_ service,
+particularly the performance is seen by the users on the network.
+
+What is runC container
+**********************
+Containers are an abstraction at the application layer that packages code
+and dependencies together. Multiple containers can run on the same machine
+and share the OS kernel with other containers, each running as
+isolated processes in user space. `runC
+<https://github.com/opencontainers/runc>`_, a lightweight universal container runtime,
+is a command-line tool for spawning and running containers according
+to the `Open Container Initiative (OCI)
+<https://www.opencontainers.org/>`_ specification.
+
+ACRN-DM QoS architecture
+************************
+In ACRN-DM QoS design, we run the ACRN-DM in a runC container environment.
+Every time we start a UOS, we first start a runC container and
+then launch the ACRN-DM within that container.
+The ACRN-DM QoS can manage these resources for Device-Model:
+
+- CPU utilization
+- Memory amount/limitation
+- I/O bandwidth
+- Network throughput
+
+.. figure:: images/acrn-dm_qos_architecture.png
+   :align: center
+
+   ACRN-DM QoS architecture
+
+ACRN-QoS CPU utilization example
+********************************
+In runC ``config.json`` we set the CPU resource as shown below for VM0 and VM1:
+
+.. code-block:: none
+
+   "cpu": {
+      "shares": 1024,
+      "quota": 1000000,
+      "period": 500000,
+      "realtimeRuntime": 950000,
+      "realtimePeriod": 1000000,
+      "mems": "0-7"
+   },
+
+In this example the `cpu.shares
+<https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/resource_management_guide/sec-cpu>`_
+value is 1024, so the VM0 and VM1 device model
+CPU utilization is ``1024 / (1024 + 1024 + 1024) = 33%``, which means
+the maximal CPU resource for the VM0 or VM1 is 33% of the entire CPU resource.
+
+.. figure:: images/cpu_utilization_image.png
+   :align: center
+
+   CPU utilization image
+
+How to use ACRN-DM QoS
+**********************
+#. Add these parameters to the ``runC.json`` file:
+
+   .. code-block:: none
+
+      # vim /usr/share/acrn/samples/nuc/runC.json
+
+   .. code-block:: none
+
+      "linux": {
+         "resources": {
+            "memory": {
+               "limit": 536870912,
+               "reservation": 536870912,
+               "swap": 536870912,
+               "kernel": -1,
+               "kernelTCP": -1,
+               "swappiness": 0,
+               "disableOOMKiller": false
+            },
+            "cpu": {
+               "shares": 1024,
+               "quota": 1000000,
+               "period": 500000,
+               "mems": "0-7"
+            },
+            "devices": [
+               {
+                  "allow": true,
+                  "access": "rwm"
+               }
+            ]
+         },
+
+   .. note:: For configuration details, refer to the `Open Containers configuration documentation
+             <https://github.com/opencontainers/runtime-spec/blob/master/config.md>`_.
+
+#. Add the UOS by ``acrnctl add`` command:
+
+   .. code-block:: none
+
+      # acrnctl add launch_uos.sh -C
+
+#. Start the UOS by ``acrnd``
+
+   .. code-block:: none
+
+      # acrnd -t