[dpdk-dev] [PATCH v2 8/8] doc: add eventdev opdl pmd docuement
liang.j.ma at intel.com
Fri Dec 15 12:26:29 CET 2017
Add the description about opdl pmd
Signed-off-by: Liang Ma <liang.j.ma at intel.com>
Signed-off-by: Peter, Mccarthy <peter.mccarthy at intel.com>
doc/guides/eventdevs/index.rst | 1 +
doc/guides/eventdevs/opdl.rst | 162 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 163 insertions(+)
create mode 100644 doc/guides/eventdevs/opdl.rst
diff --git a/doc/guides/eventdevs/index.rst b/doc/guides/eventdevs/index.rst
index ba2048c..07a41bc 100644
@@ -40,3 +40,4 @@ application trough the eventdev API.
diff --git a/doc/guides/eventdevs/opdl.rst b/doc/guides/eventdevs/opdl.rst
new file mode 100644
@@ -0,0 +1,162 @@
+.. BSD LICENSE
+ Copyright(c) 2017 Intel Corporation. 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
+ * 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.
+OPDL Eventdev Poll Mode Driver
+The OPDL (Ordered Packet Distribution Library) eventdev is a specific\
+implementation of the eventdev API. It is particularly suited to packet\
+processing workloads that have high throughput and low latency requirements.\
+All packets follow the same path through the device. The order in which\
+packets follow is determinted by the order in which queues are set up.\
+Events are left on the ring until they are transmitted. As a result packets\
+do not go out of order
+The OPDL eventdev implements a subset of features of the eventdev API;
+ * Atomic
+ * Ordered (Parallel is supported as parallel is a subset of Ordered)
+ * Single-Link
+ * Load balanced (for Atomic, Ordered, Parallel queues)
+ * Single Link (for single-link queues)
+Configuration and Options
+The software eventdev is a vdev device, and as such can be created from the
+application code, or from the EAL command line:
+* Call ``rte_vdev_init("event_opdl0")`` from the application
+* Use ``--vdev="event_opdl0"`` in the EAL options, which will call
+ rte_vdev_init() internally
+.. code-block:: console
+ ./your_eventdev_application --vdev="event_opdl0"
+Single Port Queue
+It is possible to create a Single Port Queue ``RTE_EVENT_QUEUE_CFG_SINGLE_LINK``.
+Packets dequeued from this queue do not need to be re-enqueued (as is the
+case with an ordered queue). The purpose of this queue is to allow for
+asynchronous handling of packets in the middle of a pipeline. Ordered
+queues in the middle of a pipeline cannot delete packets.
+As stated the order in which packets travel through queues is static in
+nature. They go through the queues in the order the queues are setup at
+initialisation ``rte_event_queue_setup()``. For example if an application
+sets up 3 queues, Q0, Q1, Q2 and has 3 assoicated ports P0, P1, P2 and
+P3 then packets must be
+ * Enqueued onto Q0 (typically through P0), then
+ * Dequeued from Q0 (typically through P1), then
+ * Enqueued onto Q1 (also through P1), then
+ * Dequeued from Q2 (typically through P2), then
+ * Enqueued onto Q3 (also through P2), then
+ * Dequeued from Q3 (typically through P3) and then transmitted on the relevant \
+ eth port
+The opdl implementation has a number of limitations. These limitations are
+due to the static nature of the underlying queues. It is because of this
+that the implementation can achieve such high throughput and low latency
+The following list is a comprehensive outline of the what is supported and
+the limitations / restrictions imposed by the opdl pmd
+ - The order in which packets moved between queues is static and fixed \
+ (dynamic scheduling is not supported).
+ - NEW, RELEASE are not explicitly supported. RX (first enqueue) implicitly \
+ adds NEW event types, and TX (last dequeue) implicitly does RELEASE event types.
+ - All packets follow the same path through device queues.
+ - Flows within queues are NOT supported.
+ - Event priority is NOT supported.
+ - Once the device is stopped all inflight events are lost. Applications should \
+ clear all inflight events before stopping it.
+ - Each port can only be associated with one queue.
+ - Each queue can have multiple ports associated with it.
+ - Each worker core has to dequeue the maximum burst size for that port.
+ - For performance, the rte_event flow_id should not be updated once packet\
+ is enqueued on RX.
+Validation & Statistics
+Validation can be turned on through a command line parameter
+.. code-block:: console
+If validation is turned on every packet (as opposed to just the first in
+each burst), is validated to have come from the right queue. Statistics
+are also produced in this mode. The statistics are available through the
+eventdev xstats API. Statistics are per port as follows:
+ - claim_pkts_requested
+ - claim_pkts_granted
+ - claim_non_empty
+ - claim_empty
+ - total_cycles
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