9a212dc06c
Currently the sample app user guides use hard coded code snippets,
this patch changes these to use literalinclude which will dynamically
update the snippets as changes are made to the code.
This was introduced in commit 413c75c33c ("doc: show how to include
code in guides"). Comments within the sample apps were updated to
accommodate this as part of this patch. This will help to ensure that
the code within the sample app user guides is up to date and not out
of sync with the actual code.
Signed-off-by: Conor Fogarty <conor.fogarty@intel.com>
Signed-off-by: Conor Walsh <conor.walsh@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>
137 lines
4.6 KiB
ReStructuredText
137 lines
4.6 KiB
ReStructuredText
.. SPDX-License-Identifier: BSD-3-Clause
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Copyright(c) 2015-2016 Intel Corporation.
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Keep Alive Sample Application
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=============================
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The Keep Alive application is a simple example of a
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heartbeat/watchdog for packet processing cores. It demonstrates how
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to detect 'failed' DPDK cores and notify a fault management entity
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of this failure. Its purpose is to ensure the failure of the core
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does not result in a fault that is not detectable by a management
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entity.
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Overview
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--------
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The application demonstrates how to protect against 'silent outages'
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on packet processing cores. A Keep Alive Monitor Agent Core (main)
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monitors the state of packet processing cores (worker cores) by
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dispatching pings at a regular time interval (default is 5ms) and
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monitoring the state of the cores. Cores states are: Alive, MIA, Dead
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or Buried. MIA indicates a missed ping, and Dead indicates two missed
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pings within the specified time interval. When a core is Dead, a
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callback function is invoked to restart the packet processing core;
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A real life application might use this callback function to notify a
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higher level fault management entity of the core failure in order to
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take the appropriate corrective action.
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Note: Only the worker cores are monitored. A local (on the host) mechanism
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or agent to supervise the Keep Alive Monitor Agent Core DPDK core is required
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to detect its failure.
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Note: This application is based on the :doc:`l2_forward_real_virtual`. As
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such, the initialization and run-time paths are very similar to those
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of the L2 forwarding application.
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Compiling the Application
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-------------------------
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To compile the sample application see :doc:`compiling`.
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The application is located in the ``l2fwd_keep_alive`` sub-directory.
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Running the Application
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-----------------------
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The application has a number of command line options:
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.. code-block:: console
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./<build_dir>/examples/dpdk-l2fwd-keepalive [EAL options] \
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-- -p PORTMASK [-q NQ] [-K PERIOD] [-T PERIOD]
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where,
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* ``p PORTMASK``: A hexadecimal bitmask of the ports to configure
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* ``q NQ``: A number of queues (=ports) per lcore (default is 1)
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* ``K PERIOD``: Heartbeat check period in ms(5ms default; 86400 max)
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* ``T PERIOD``: statistics will be refreshed each PERIOD seconds (0 to
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disable, 10 default, 86400 maximum).
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To run the application in linux environment with 4 lcores, 16 ports
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8 RX queues per lcore and a ping interval of 10ms, issue the command:
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.. code-block:: console
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./<build_dir>/examples/dpdk-l2fwd-keepalive -l 0-3 -n 4 -- -q 8 -p ffff -K 10
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Refer to the *DPDK Getting Started Guide* for general information on
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running applications and the Environment Abstraction Layer (EAL)
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options.
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Explanation
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-----------
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The following sections provide some explanation of the The
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Keep-Alive/'Liveliness' conceptual scheme. As mentioned in the
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overview section, the initialization and run-time paths are very
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similar to those of the :doc:`l2_forward_real_virtual`.
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The Keep-Alive/'Liveliness' conceptual scheme:
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* A Keep- Alive Agent Runs every N Milliseconds.
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* DPDK Cores respond to the keep-alive agent.
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* If keep-alive agent detects time-outs, it notifies the
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fault management entity through a callback function.
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The following sections provide some explanation of the code aspects
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that are specific to the Keep Alive sample application.
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The keepalive functionality is initialized with a struct
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rte_keepalive and the callback function to invoke in the
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case of a timeout.
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.. literalinclude:: ../../../examples/l2fwd-keepalive/main.c
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:language: c
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:start-after: Initialize keepalive functionality. 8<
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:end-before: >8 End of initializing keepalive functionality.
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:dedent: 2
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The function that issues the pings keepalive_dispatch_pings()
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is configured to run every check_period milliseconds.
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.. literalinclude:: ../../../examples/l2fwd-keepalive/main.c
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:language: c
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:start-after: Issues the pings keepalive_dispatch_pings(). 8<
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:end-before: >8 End of issuing the pings keepalive_dispatch_pings().
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:dedent: 2
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The rest of the initialization and run-time path follows
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the same paths as the L2 forwarding application. The only
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addition to the main processing loop is the mark alive
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functionality and the example random failures.
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.. literalinclude:: ../../../examples/l2fwd-keepalive/main.c
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:language: c
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:start-after: Keepalive heartbeat. 8<
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:end-before: >8 End of keepalive heartbeat.
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:dedent: 2
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The rte_keepalive_mark_alive function simply sets the core state to alive.
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.. code-block:: c
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static inline void
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rte_keepalive_mark_alive(struct rte_keepalive *keepcfg)
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{
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keepcfg->live_data[rte_lcore_id()].core_state = RTE_KA_STATE_ALIVE;
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}
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