[dpdk-dev] [RFC v2 PATCH 0/8] event: eventdev OPDL PMD

[Ma, Liang]

ChangeLog
[v2]
  1. merge the opdl eventdev unit test code into opdl pmd.
  2. propose three new capability capability flags for overall eventdev.
  3. remove the opdl pmd example code. 
  4. remove the opdl pmd example doc.


On 15 Dec 11:26, Liang Ma wrote:
> 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 which packets  follow is determinted by the order in which
> queues are set up. Packets are left on the ring until they are transmitted.
> As a result packets do not go out of order.
> 
> Features:
> 
> The OPDL eventdev implements a subset of features of the eventdev API;
> 
> Queues
>  * Atomic
>  * Ordered (Parallel is supported as parallel is a subset of Ordered)
>  * Single-Link
> 
> Ports
>  * Load balanced (for Atomic, Ordered, Parallel queues)
>  * Single Link (for single-link queues)
> 
> 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.
> 
> 
> Queue Dependencies
> 
> 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
> 
> 
> Limitations
> 
> 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 op type 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.
> 
> 
> Reference
> General concept of event driven programming model
> [http://dpdk.org/doc/guides/eventdevs/index.html]
> 
> Original Ordered Pipeline Design slides 
> [https://dpdksummit.com/Archive/pdf/2017Asia/DPDK-China2017-Ma-OPDL.pdf]
>
> 
> Liang Ma (8):
>   event/opdl:  add the opdl ring infrastructure library
>   event/opdl: add the opdl pmd header and init helper function
>   event/opdl: add the opdl pmd main body and xstats helper function
>   eventdev/opdl: opdl eventdev pmd unit test function
>   lib/librte_eventdev: extend the eventdev capability flags
>   event/*: apply the three new capability flags for sw/dppa2/octeontx
>   event/opdl: update the build system to enable compilation
>   doc: add eventdev opdl pmd docuement
> 
>  config/common_base                                |    6 +
>  doc/guides/eventdevs/index.rst                    |    1 +
>  doc/guides/eventdevs/opdl.rst                     |  162 +++
>  drivers/event/Makefile                            |    1 +
>  drivers/event/dpaa2/dpaa2_eventdev.c              |    5 +-
>  drivers/event/octeontx/ssovf_evdev.c              |    5 +-
>  drivers/event/opdl/Makefile                       |   66 ++
>  drivers/event/opdl/opdl_evdev.c                   |  744 +++++++++++++
>  drivers/event/opdl/opdl_evdev.h                   |  354 ++++++
>  drivers/event/opdl/opdl_evdev_init.c              |  951 ++++++++++++++++
>  drivers/event/opdl/opdl_evdev_xstats.c            |  205 ++++
>  drivers/event/opdl/opdl_ring.c                    | 1232 +++++++++++++++++++++
>  drivers/event/opdl/opdl_ring.h                    |  601 ++++++++++
>  drivers/event/opdl/opdl_test.c                    | 1079 ++++++++++++++++++
>  drivers/event/opdl/rte_pmd_evdev_opdl_version.map |    3 +
>  drivers/event/sw/sw_evdev.c                       |    5 +-
>  lib/librte_eventdev/rte_eventdev.h                |   22 +
>  mk/rte.app.mk                                     |    1 +
>  18 files changed, 5440 insertions(+), 3 deletions(-)
>  create mode 100644 doc/guides/eventdevs/opdl.rst
>  create mode 100644 drivers/event/opdl/Makefile
>  create mode 100644 drivers/event/opdl/opdl_evdev.c
>  create mode 100644 drivers/event/opdl/opdl_evdev.h
>  create mode 100644 drivers/event/opdl/opdl_evdev_init.c
>  create mode 100644 drivers/event/opdl/opdl_evdev_xstats.c
>  create mode 100644 drivers/event/opdl/opdl_ring.c
>  create mode 100644 drivers/event/opdl/opdl_ring.h
>  create mode 100644 drivers/event/opdl/opdl_test.c
>  create mode 100644 drivers/event/opdl/rte_pmd_evdev_opdl_version.map
> 
> -- 
> 2.7.5
> 
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