Re: [dpdk-dev] [PATCH v4 0/8] Introduce event vectorization

[Jerin Jacob <jerinjacobk@gmail.com>]

On Sat, Mar 20, 2021 at 2:27 AM <pbhagavatula@marvell.com> wrote:
>
> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
>
> In traditional event programming model, events are identified by a
> flow-id and a uintptr_t. The flow-id uniquely identifies a given event
> and determines the order of scheduling based on schedule type, the
> uintptr_t holds a single object.
>
> Event devices also support burst mode with configurable dequeue depth,
> i.e. each dequeue call would return multiple events and each event
> might be at a different stage of the pipeline.
> Having a burst of events belonging to different stages in a dequeue
> burst is not only difficult to vectorize but also increases the scheduler
> overhead and application overhead of pipelining events further.
> Using event vectors we see a performance gain of ~628% as shown in [1].
>
> By introducing event vectorization, each event will be capable of holding
> multiple uintptr_t of the same flow thereby allowing applications
> to vectorize their pipeline and reduce the complexity of pipelining
> events across multiple stages. This also reduces the complexity of handling
> enqueue and dequeue on an event device.
>
> Since event devices are transparent to the events they are scheduling
> so the event producers such as eth_rx_adapter, crypto_adapter , etc..
> are responsible for vectorizing the buffers of the same flow into a single
> event.
>
> The series also breaks ABI in the patch [8/8] which is targetted to the
> v21.11 release.
>
> The dpdk-test-eventdev application has been updated with options to test
> multiple vector sizes and timeouts.
>
> [1]
> As for performance improvement, with a ARM Cortex-A72 equivalent processer,
> software event device (--vdev=event_sw0), single worker core, single stage
> and using one service core for Rx adapter, Tx adapter, Scheduling.
>
> Without event vectorization:
>     ./build/app/dpdk-test-eventdev -l 7-23 -s 0x700 --vdev="event_sw0" --
>          --prod_type_ethdev --nb_pkts=0 --verbose 2 --test=pipeline_queue
>          --stlist=a --wlcores=20
>     Port[0] using Rx adapter[0] configured
>     Port[0] using Tx adapter[0] Configured
>     4.728 mpps avg 4.728 mpps
>
> With event vectorization:
>     ./build/app/dpdk-test-eventdev -l 7-23 -s 0x700 --vdev="event_sw0" --
>         --prod_type_ethdev --nb_pkts=0 --verbose 2 --test=pipeline_queue
>         --stlist=a --wlcores=20 --enable_vector --nb_eth_queues 1
>         --vector_size 256
>     Port[0] using Rx adapter[0] configured
>     Port[0] using Tx adapter[0] Configured
>     34.383 mpps avg 34.383 mpps
>
> Having dedicated service cores for each Rx queues and tweaking the vector,
> dequeue burst size would further improve performance.
>
> API usage is shown below:
>
> Configuration:
>
>         struct rte_event_eth_rx_adapter_event_vector_config vec_conf;
>
>         vector_pool = rte_event_vector_pool_create("vector_pool",
>                         nb_elem, 0, vector_size, socket_id);
>
>         rte_event_eth_rx_adapter_create(id, event_id, &adptr_conf);
>         rte_event_eth_rx_adapter_queue_add(id, eth_id, -1, &queue_conf);
>         if (cap & RTE_EVENT_ETH_RX_ADAPTER_CAP_EVENT_VECTOR) {
>                 vec_conf.vector_sz = vector_size;
>                 vec_conf.vector_timeout_ns = vector_tmo_nsec;
>                 vec_conf.vector_mp = vector_pool;
>                 rte_event_eth_rx_adapter_queue_event_vector_config(id,
>                                 eth_id, -1, &vec_conf);
>         }
>
> Fastpath:
>
>         num = rte_event_dequeue_burst(event_id, port_id, &ev, 1, 0);
>         if (!num)
>                 continue;
>
>         if (ev.event_type & RTE_EVENT_TYPE_VECTOR) {
>                 switch (ev.event_type) {
>                 case RTE_EVENT_TYPE_ETHDEV_VECTOR:
>                 case RTE_EVENT_TYPE_ETH_RX_ADAPTER_VECTOR:
>                         struct rte_mbuf **mbufs;
>
>                         mbufs = ev.vector_ev->mbufs;
>                         for (i = 0; i < ev.vector_ev->nb_elem; i++)
>                                 //Process mbufs.
>                         break;
>                 case ...
>                 }
>         }
>         ...
>
> v4 Changes:
> - Fix missing event vector structure in event structure.(Jay)
>
> v3 Changes:
> - Fix unintended formatting changes.
>
> v2 Changes:
> - Multiple gramatical and style fixes.(Jerin)
> - Add parameter to define vector size in power of 2. (Jerin)
> - Redo patch series w/o breaking ABI till the last patch.(David)
> - Add deprication notice to announce ABI break in 21.11.(David)
> - Add vector limits validation to app/test-eventdev.
>
> Pavan Nikhilesh (8):
>   eventdev: introduce event vector capability
>   eventdev: introduce event vector Rx capability
>   eventdev: introduce event vector Tx capability
>   eventdev: add Rx adapter event vector support
>   eventdev: add Tx adapter event vector support
>   app/eventdev: add event vector mode in pipeline test
>   doc: announce event Rx adapter config changes
>   eventdev: simplify Rx adapter event vector config
>
>  app/test-eventdev/evt_common.h                |   4 +
>  app/test-eventdev/evt_options.c               |  52 +++
>  app/test-eventdev/evt_options.h               |   4 +
>  app/test-eventdev/test_pipeline_atq.c         | 310 +++++++++++++++--
>  app/test-eventdev/test_pipeline_common.c      | 105 +++++-
>  app/test-eventdev/test_pipeline_common.h      |  18 +
>  app/test-eventdev/test_pipeline_queue.c       | 320 ++++++++++++++++--
>  .../prog_guide/event_ethernet_rx_adapter.rst  |  38 +++
>  .../prog_guide/event_ethernet_tx_adapter.rst  |  12 +
>  doc/guides/prog_guide/eventdev.rst            |  36 +-
>  doc/guides/rel_notes/deprecation.rst          |   9 +
>  doc/guides/tools/testeventdev.rst             |  28 ++
>  lib/librte_eventdev/eventdev_pmd.h            |  31 +-
>  .../rte_event_eth_rx_adapter.c                | 305 ++++++++++++++++-
>  .../rte_event_eth_rx_adapter.h                |  68 ++++
>  .../rte_event_eth_tx_adapter.c                |  66 +++-
>  lib/librte_eventdev/rte_eventdev.c            |  11 +-
>  lib/librte_eventdev/rte_eventdev.h            | 144 +++++++-
>  lib/librte_eventdev/version.map               |   4 +
>  19 files changed, 1479 insertions(+), 86 deletions(-)

Please update release notes(doc/guides/rel_notes/release_21_05.rst)
for this feature.

If there are no more comments on this series from others. IMO, Good to
merge the next series for RC1.

>
> --
> 2.17.1
>