Enable Shared CPU usage using Overrides

- Created openstack folder in Admin Tasks guide
    - created 'configure dedicated and shered cpu pools on hosts'
    - created 'index' file



Previous gerrit review abandoned as this is only WRO.
Gerrit review: https://review.opendev.org/c/starlingx/docs/+/796527

Signed-off-by: Adil <mohamed.adilassakkali@windriver.com>
Change-Id: I48f66b8f9509bc0e064a2ba648d9f8dd21ed9743

doc/source/admintasks/index.rst

@@ -62,3 +62,11 @@ Metrics Server
 
    kubernetes-admin-tutorials-metrics-server
 
+-------------------
+StarlingX OpenStack
+-------------------
+
+.. toctree::
+   :maxdepth: 2
+
+   openstack/index

doc/source/admintasks/openstack/configure-dedicated-and-shared-cpu-pools-on-hosts.rst

@@ -0,0 +1,58 @@
+
+.. _configure-dedicated-and-shared-cpu-pools-on-hosts:
+
+========================================================
+Configure Nova's Dedicated and Shared CPU Pools on Hosts
+========================================================
+
+|prod| supports configuring Nova's dedicated and shared CPU pools on a per
+openstack-compute host basis.
+
+This provides support for users to customize their VM's CPU pinning policies to
+either dedicated or shared, with the dedicated policy providing improved near-real-time
+performance. For more details, see: `https://docs.openstack.org/nova/latest/admin/cpu-topologies.html <https://docs.openstack.org/nova/latest/admin/cpu-topologies.html>`_.
+
+For an openstack-compute host:
+
+- host CPUs configured as **application** function will be mapped to Nova's Shared CPU pool,
+
+  and
+
+- host CPUs configured as **application-isolated** function will be mapped to Nova's Dedicated CPU pool.
+
+The above mapping is done automatically, via system-generated Nova Helm Chart overrides,
+when the openstack application is applied.
+
+The following restrictions apply when configuring host CPU functions:
+
+-   There must be at least one platform and at least one application or
+    application-isolated core on each openstack-compute host.
+
+For example:
+
+.. code-block:: none
+
+    ~(keystone)admin)$ system host-lock worker-1
+    ~(keystone)admin)$ system host-cpu-modify -f platform -p0 1 worker-1
+    ~(keystone)admin)$ system host-cpu-modify -f application-isolated -p0 15 worker-1
+    ~(keystone)admin)$ system host-cpu-modify -f application-isolated -p1 15 worker-1
+    ~(keystone)admin)$ system host-unlock worker-1
+    ~(keystone)admin)$ system application-apply stx-openstack
+
+To configure a flavor to use the dedicated CPU policy, run:
+
+.. code-block:: none
+
+    ~(keystone)$ openstack flavor set [FLAVOR_ID] --property hw:cpu_policy=dedicated
+
+It is also possible to configure the CPU policy via image metadata:
+
+.. code-block:: none
+
+    ~(keystone)$ openstack image set [IMAGE_ID] --property hw_cpu_policy=dedicated
+
+.. only:: partner
+
+    .. include:: /_includes/isolating-cpu-cores-to-enhance-application-performance.rest
+       :start-after: changes-relative-to-root-begin
+       :end-before: changes-relative-to-root-end

doc/source/admintasks/openstack/index.rst

@@ -0,0 +1,12 @@
+-------------------
+StarlingX OpenStack
+-------------------
+
+===========
+Admin Tasks
+===========
+
+.. toctree::
+   :maxdepth: 1
+
+   configure-dedicated-and-shared-cpu-pools-on-hosts