[dpdk-dev] [PATCH v3 2/3] docs: add keep alive sample app guide

[Remy Horton <remy.horton@intel.com>]

Signed-off-by: Maryam Tahhan <maryam.tahhan@intel.com>
Signed-off-by: John J Browne <john.j.browne@intel.com>
Signed-off-by: Remy Horton <remy.horton@intel.com>
---
 doc/guides/sample_app_ug/index.rst      |   1 +
 doc/guides/sample_app_ug/keep_alive.rst | 191 ++++++++++++++++++++++++++++++++
 2 files changed, 192 insertions(+)
 create mode 100644 doc/guides/sample_app_ug/keep_alive.rst

diff --git a/doc/guides/sample_app_ug/index.rst b/doc/guides/sample_app_ug/index.rst
index 9beedd9..11b8b14 100644
--- a/doc/guides/sample_app_ug/index.rst
+++ b/doc/guides/sample_app_ug/index.rst
@@ -49,6 +49,7 @@ Sample Applications User Guide
     ipv4_multicast
     ip_reassembly
     kernel_nic_interface
+    keep_alive
     l2_forward_job_stats
     l2_forward_real_virtual
     l3_forward
diff --git a/doc/guides/sample_app_ug/keep_alive.rst b/doc/guides/sample_app_ug/keep_alive.rst
new file mode 100644
index 0000000..080811b
--- /dev/null
+++ b/doc/guides/sample_app_ug/keep_alive.rst
@@ -0,0 +1,191 @@
+
+..  BSD LICENSE
+    Copyright(c) 2015 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.
+
+Keep Alive Sample Application
+=============================
+
+The Keep Alive application is a simple example of a
+heartbeat/watchdog for packet processing cores. It demonstrates how
+to detect 'failed' DPDK cores and notify a fault management entity
+of this failure. Its purpose is to ensure the failure of the core
+does not result in a fault that is not detectable by a management
+entity.
+
+
+Overview
+--------
+
+The application demonstrates how to protect against 'silent outages'
+on packet processing cores. A Keep Alive Monitor Agent Core (master)
+monitors the state of packet processing cores (worker cores) by
+dispatching pings at a regular time interval (default is 5ms) and
+monitoring the state of the cores. Cores states are: Alive, MIA, Dead
+or Buried. MIA indicates a missed ping, and Dead indicates two missed
+pings within the specified time interval. When a core is Dead, a
+callback function is invoked to restart the packet processing core;
+A real life application might use this callback function to notify a
+higher level fault management entity of the core failure in order to
+take the appropriate corrective action.
+
+Note: Only the worker cores are monitored. A local (on the host) mechanism
+or agent to supervise the Keep Alive Monitor Agent Core DPDK core is required
+to detect its failure.
+
+Note: This application is based on the L2 forwarding application. As
+such, the initialization and run-time paths are very similar to those
+of the L2 forwarding application.
+
+Compiling the Application
+-------------------------
+
+To compile the application:
+
+#.  Go to the sample application directory:
+
+    .. code-block:: console
+
+        export RTE_SDK=/path/to/rte_sdk cd ${RTE_SDK}/examples/keep_alive
+
+#.  Set the target (a default target is used if not specified). For example:
+
+    .. code-block:: console
+
+        export RTE_TARGET=x86_64-native-linuxapp-gcc
+
+    See the *DPDK Getting Started Guide* for possible RTE_TARGET values.
+
+#.  Build the application:
+
+    .. code-block:: console
+
+        make
+
+Running the Application
+-----------------------
+
+The application has a number of command line options:
+
+.. code-block:: console
+
+    ./build/l2fwd-keepalive [EAL options] \
+            -- -p PORTMASK [-q NQ] [-K PERIOD] [-T PERIOD]
+
+where,
+
+* ``p PORTMASK``: A hexadecimal bitmask of the ports to configure
+
+* ``q NQ``: A number of queues (=ports) per lcore (default is 1)
+
+* ``K PERIOD``: Heartbeat check period in ms(5ms default; 86400 max)
+
+* ``T PERIOD``: statistics will be refreshed each PERIOD seconds (0 to
+  disable, 10 default, 86400 maximum).
+
+To run the application in linuxapp environment with 4 lcores, 16 ports
+8 RX queues per lcore and a ping interval of 10ms, issue the command:
+
+.. code-block:: console
+
+    ./build/l2fwd-keepalive -c f -n 4 -- -q 8 -p ffff -K 10
+
+Refer to the *DPDK Getting Started Guide* for general information on
+running applications and the Environment Abstraction Layer (EAL)
+options.
+
+
+Explanation
+-----------
+
+The following sections provide some explanation of the The
+Keep-Alive/'Liveliness' conceptual scheme. As mentioned in the
+overview section, the initialization and run-time paths are very
+similar to those of the L2 forwarding application (see Chapter 9
+"L2 Forwarding Sample Application (in Real and Virtualized
+Environments)" for more information).
+
+The Keep-Alive/'Liveliness' conceptual scheme:
+
+* A Keep- Alive Agent Runs every N Milliseconds.
+
+* DPDK Cores respond to the keep-alive agent.
+
+* If keep-alive agent detects time-outs, it notifies the
+  fault management entity through a callback function.
+
+The following sections provide some explanation of the code aspects
+that are specific to the Keep Alive sample application.
+
+The heartbeat functionality is initialized with a struct
+rte_heartbeat and the callback function to invoke in the
+case of a timeout.
+
+.. code-block:: c
+
+    rte_global_keepalive_info = rte_keepalive_create(&dead_core, NULL);
+    if (rte_global_hbeat_info == NULL)
+        rte_exit(EXIT_FAILURE, "keepalive_create() failed");
+
+The function that issues the pings hbeat_dispatch_pings()
+is configured to run every check_period milliseconds.
+
+.. code-block:: c
+
+    if (rte_timer_reset(&hb_timer,
+            (check_period * rte_get_timer_hz()) / 1000,
+            PERIODICAL,
+            rte_lcore_id(),
+            &hbeat_dispatch_pings, rte_global_keepalive_info
+            ) != 0 )
+        rte_exit(EXIT_FAILURE, "Keepalive setup failure.\n");
+
+The rest of the initialization and run-time path follows
+the same paths as the the L2 forwarding application. The only
+addition to the main processing loop is the mark alive
+functionality and the example random failures.
+
+.. code-block:: c
+
+    rte_keepalive_mark_alive(&rte_global_hbeat_info);
+    cur_tsc = rte_rdtsc();
+
+    /* Die randomly within 7 secs for demo purposes.. */
+    if (cur_tsc - tsc_initial > tsc_lifetime)
+    break;
+
+The rte_keepalive_mark_alive function simply sets the core state to alive.
+
+.. code-block:: c
+
+    static inline void
+    rte_keepalive_mark_alive(struct rte_heartbeat *keepcfg)
+    {
+        keepcfg->state_flags[rte_lcore_id()] = 1;
+    }
-- 
1.9.3