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+
+.. BSD LICENSE
+ Copyright(c) 2015-2016 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 :doc:`l2_forward_real_virtual`. 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 :doc:`l2_forward_real_virtual`.
+
+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 keepalive functionality is initialized with a struct
+rte_keepalive 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_keepalive_info == NULL)
+ rte_exit(EXIT_FAILURE, "keepalive_create() failed");
+
+The function that issues the pings keepalive_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(),
+ &rte_keepalive_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_keepalive_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_keepalive *keepcfg)
+ {
+ keepcfg->state_flags[rte_lcore_id()] = ALIVE;
+ }