docs: update collectd information

Update collectd description and data model as well as the information
about the available collectd plugins and plugins that are a work in
progress.

Change-Id: I54d1945a9cfdd1511ca34c2c7e542b4c24b561e6
JIRA: DOCS-106
Signed-off-by: Maryam Tahhan <maryam.tahhan@intel.com>

1 files changed, 140 insertions, 16 deletions

diff --git a/docs/requirements/02-measuring_telco_traffic_and_performance_KPIs.rst b/docs/requirements/02-measuring_telco_traffic_and_performance_KPIs.rst
index 511128c..7f0d486 100644
--- a/docs/requirements/02-measuring_telco_traffic_and_performance_KPIs.rst
+++ b/docs/requirements/02-measuring_telco_traffic_and_performance_KPIs.rst
@@ -4,7 +4,7 @@
 
 Measuring Telco Traffic and Performance KPIs
 ============================================
-This section will look at what SFQM has done to enable Measuring Telco Traffic
+This section will discuss the SFQM features that enable Measuring Telco Traffic
 and Performance KPIs.
 
 .. Figure:: stats_and_timestamps.png
@@ -28,30 +28,146 @@ and Performance KPIs.
   * For DPDK 2.2 the API was implemented for igb, i40e and all the Virtual
     Functions (VFs) for all drivers.
 
+  * For DPDK 16.07 the API migrated from using string value pairs to using id
+    value pairs, improving the overall performance of the API.
+
 Monitoring DPDK interfaces
 ===========================
 With the features SFQM enabled in DPDK to enable measuring Telco traffic and
 performance KPIs, we can now retrieve NIC statistics including error stats and
 relay them to a DPDK user. The next step is to enable monitoring of the DPDK
-interfaces based on the stats that we are retrieving from the NICs, and relay
+interfaces based on the stats that we are retrieving from the NICs, by relaying
 the information to a higher level Fault Management entity. To enable this SFQM
 has been enabling a number of plugins for collectd.
 
-collectd is is a daemon which collects system performance statistics periodically
-and provides mechanisms to store the values in a variety of ways. It supports
-more than 90 different plugins to retrieve platform information, such as CPU
-utilization, and is capable of publishing/writing the information is gathers to
-a number of endpoints through its write plugins.
+collectd
+---------
+collectd is a daemon which collects system performance statistics periodically
+and provides a variety of mechanisms to publish the collected metrics. It
+supports more than 90 different input and output plugins. Input plugins retrieve
+metrics and publish them to the collectd deamon, while output plugins publish
+the data they receive to an end point. collectd also has infrastructure to
+support thresholding and notification.
+
+Statistics and Notifications
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Within collectd notifications and performance data are dispatched in the same
+way. There are producer plugins (plugins that create notifications/metrics),
+and consumer plugins (plugins that receive notifications/metrics and do
+something with them).
+
+Statistics in collectd consist of a value list. A value list includes:
+
+* Values, can be one of:
+
+  * Derive: used for values where a change in the value since it's last been
+    read is of interest. Can be used to calculate and store a rate.
+
+  * Counter: similar to derive values, but take the possibility of a counter
+    wrap around into consideration.
+
+  * Gauge: used for values that are stored as is.
+
+  * Absolute: used for counters that are reset after reading.
+
+* Value length: the number of values in the data set.
+
+* Time: timestamp at which the value was collected.
+
+* Interval: interval at which to expect a new value.
+
+* Host: used to identify the host.
+
+* Plugin: used to identify the plugin.
+
+* Plugin instance (optional): used to group a set of values together. For e.g.
+  values belonging to a DPDK interface.
+
+* Type: unit used to measure a value. In other words used to refer to a data
+  set.
+
+* Type instance (optional): used to distinguish between values that have an
+  identical type.
+
+* meta data: an opaque data structure that enables the passing of additional
+  information about a value list. "Meta data in the global cache can be used to
+  store arbitrary information about an identifier" [7].
+
+Host, plugin, plugin instance, type and type instance uniquely identify a
+collectd value.
+
+Values lists are often accompanied by data sets that describe the values in more
+detail. Data sets consist of:
+
+* A type: a name which uniquely identifies a data set.
+
+* One or more data sources (entries in a data set) which include:
+
+  * The name of the data source. If there is only a single data source this is
+    set to "value".
+
+  * The type of the data source, one of: counter, gauge, absolute or derive.
 
-SFQM has been enabling two collectd plugins to collect DPDK NIC statistics and
-push the stats to Ceilometer:
+  * A min and a max value.
 
-* dpdkstat plugin: A read plugin that retrieve stats from the DPDK extended NIC
-  stats API.
-* ceilometer plugin: A write plugin that pushes the retrieved stats to
+Types in collectd are defined in types.db. Examples of types in types.db:
+
+.. code-block:: console
+
+    bitrate    value:GAUGE:0:4294967295
+    counter    value:COUNTER:U:U
+    if_octets  rx:COUNTER:0:4294967295, tx:COUNTER:0:4294967295
+
+In the example above if_octets has two data sources: tx and rx.
+
+Notifications in collectd are generic messages containing:
+
+* An associated severity, which can be one of OKAY, WARNING, and FAILURE.
+
+* A time.
+
+* A Message
+
+* A host.
+
+* A plugin.
+
+* A plugin instance (optional).
+
+* A type.
+
+* A types instance (optional).
+
+* Meta-data.
+
+collectd plugins
+----------------
+SFQM has enabled three collectd plugins to date:
+
+* `dpdkstat plugin`_: A read plugin that retrieve stats from the DPDK extended
+   NIC stats API.
+
+* `ceilometer plugin`_: A write plugin that pushes the retrieved stats to
   Ceilometer. It's capable of pushing any stats read through collectd to
   Ceilometer, not just the DPDK stats.
 
+* `hugepages plugin`_:  A read plugin that retrieves the number of available
+  and free hugepages on a platform as well as what is available in terms of
+  hugepages per socket.
+
+Other plugins in progress:
+
+* dpdkevents:  A read plugin that retrieves DPDK link status and DPDK
+  forwarding cores liveliness status (DPDK Keep Alive).
+
+* Open vSwitch stats Plugin: A read plugin that retrieve flow and interface
+  stats from OVS.
+
+* Open vSwitch events Plugin: A read plugin that retrieves events from OVS.
+
+
+Monitoring Interfaces and Openstack Support
+-------------------------------------------
 .. Figure:: monitoring_interfaces.png
 
    Monitoring Interfaces and Openstack Support
@@ -63,9 +179,17 @@ and publishing the retrieved stats to Ceilometer through the ceilometer plugin.
 
 To see this demo in action please checkout: `SFQM OPNFV Summit demo`_
 
-Future enahancements to the DPDK stats plugin include:
-
-* Integration of DPDK Keep Alive functionality.
-* Implementation of the ability to retrieve link status.
+References
+----------
+[1] https://collectd.org/wiki/index.php/Naming_schema
+[2] https://github.com/collectd/collectd/blob/master/src/daemon/plugin.h
+[3] https://collectd.org/wiki/index.php/Value_list_t
+[4] https://collectd.org/wiki/index.php/Data_set
+[5] https://collectd.org/documentation/manpages/types.db.5.shtml
+[6] https://collectd.org/wiki/index.php/Data_source
+[7] https://collectd.org/wiki/index.php/Meta_Data_Interface
 
 .. _SFQM OPNFV Summit demo: https://prezi.com/kjv6o8ixs6se/software-fastpath-service-quality-metrics-demo/
+.. _dpdkstat plugin: https://github.com/maryamtahhan/collectd-with-DPDK/tree/dpdkstat
+.. _ceilometer plugin: https://github.com/openstack/collectd-ceilometer-plugin/tree/stable/mitaka
+.. _hugepages plugin: https://github.com/maryamtahhan/collectd-with-DPDK/tree/hugepages