Re: [dpdk-dev] [PATCH v2 27/27] event/dlb2: Change device name to dlb_event

[Jerin Jacob <jerinjacobk@gmail.com>]

On Wed, Mar 31, 2021 at 1:09 AM Timothy McDaniel
<timothy.mcdaniel@intel.com> wrote:
>
> Updated eventdev device name to be dlb_event instead of
> dlb2_event.  The new name will be used for all versions
> of the DLB hardware. This change required corresponding changes
> to the the directory name that contains the PMD, as well
> as the documentation files, build infrastructure, and PMD
> specific APIs.
>
> Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>


# Change the patch subject to event/dlb:
# Also, I can still still see[1],  doc/guides/eventdevs/dlb.rst and
doc/guides/eventdevs/dlb2.rst.
Let have only one .rst file for one driver.
# Please check the documentation carefully, I see the example in vdev
arguments still messed up with dlb2 and dlb1.
Please check and correct as needed.


[1]
[for-main]dell[dpdk-next-eventdev] $ git diff HEAD~27 --stat
 MAINTAINERS                                              |    6 +-
 app/test/test_eventdev.c                                 |    6 +-
 config/rte_config.h                                      |   11 +-
 doc/api/doxy-api-index.md                                |    2 +-
 doc/api/doxy-api.conf.in                                 |    2 +-
 doc/guides/eventdevs/dlb.rst                             |  390
++++++++++++++++
 doc/guides/eventdevs/dlb.rst                          |   75 ++-
 doc/guides/eventdevs/index.rst                           |    2 +-
 doc/guides/rel_notes/release_21_05.rst                   |    5 +
 drivers/event/{dlb2 => dlb}/dlb2.c                       |  451
++++++++++++-----

> +/* DLB defines */
> +#define RTE_LIBRTE_PMD_DLB_POLL_INTERVAL 1000
> +#undef RTE_LIBRTE_PMD_DLB_QUELL_STATS
> +#define RTE_LIBRTE_PMD_DLB_SW_CREDIT_QUANTA 32
> +#define RTE_LIBRTE_PMD_DLB_DEFAULT_DEPTH_THRESH 256


PLEASE MOVE THIS ALL TO RUNTIME. If it not used in fastpath.


> +Deferred Scheduling
> +~~~~~~~~~~~~~~~~~~~
> +
> +The DLB2 PMD's default behavior for managing a CQ is to "pop" the CQ once per
> +dequeued event before returning from rte_event_dequeue_burst(). This frees the
> +corresponding entries in the CQ, which enables the DLB2 to schedule more events
> +to it.
> +
> +To support applications seeking finer-grained scheduling control -- for example
> +deferring scheduling to get the best possible priority scheduling and
> +load-balancing -- the PMD supports a deferred scheduling mode. In this mode,
> +the CQ entry is not popped until the *subsequent* rte_event_dequeue_burst()
> +call. This mode only applies to load-balanced event ports with dequeue depth of
> +1.
> +
> +To enable deferred scheduling, use the defer_sched vdev argument like so:
> +
> +    .. code-block:: console
> +
> +       --vdev=dlb1_event,defer_sched=on

It should be dlb_event. Right?

> +
> +Atomic Inflights Allocation
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +In the last stage prior to scheduling an atomic event to a CQ, DLB2 holds the
> +inflight event in a temporary buffer that is divided among load-balanced
> +queues. If a queue's atomic buffer storage fills up, this can result in
> +head-of-line-blocking. For example:
> +
> +- An LDB queue allocated N atomic buffer entries
> +- All N entries are filled with events from flow X, which is pinned to CQ 0.
> +
> +Until CQ 0 releases 1+ events, no other atomic flows for that LDB queue can be
> +scheduled. The likelihood of this case depends on the eventdev configuration,
> +traffic behavior, event processing latency, potential for a worker to be
> +interrupted or otherwise delayed, etc.
> +
> +By default, the PMD allocates 16 buffer entries for each load-balanced queue,
> +which provides an even division across all 128 queues but potentially wastes
> +buffer space (e.g. if not all queues are used, or aren't used for atomic
> +scheduling).
> +
> +The PMD provides a dev arg to override the default per-queue allocation. To
> +increase a vdev's per-queue atomic-inflight allocation to (for example) 64:
> +
> +    .. code-block:: console
> +
> +       --vdev=dlb1_event,atm_inflights=64

It should be dlb_event. Right?

> +
> +QID Depth Threshold
> +~~~~~~~~~~~~~~~~~~~
> +
> +DLB2 supports setting and tracking queue depth thresholds. Hardware uses
> +the thresholds to track how full a queue is compared to its threshold.
> +Four buckets are used
> +
> +- Less than or equal to 50% of queue depth threshold
> +- Greater than 50%, but less than or equal to 75% of depth threshold
> +- Greater than 75%, but less than or equal to 100% of depth threshold
> +- Greater than 100% of depth thresholds
> +
> +Per queue threshold metrics are tracked in the DLB2 xstats, and are also
> +returned in the impl_opaque field of each received event.
> +
> +The per qid threshold can be specified as part of the device args, and
> +can be applied to all queue, a range of queues, or a single queue, as
> +shown below.
> +
> +    .. code-block:: console
> +
> +       --vdev=dlb2_event,qid_depth_thresh=all:<threshold_value>
> +       --vdev=dlb2_event,qid_depth_thresh=qidA-qidB:<threshold_value>
> +       --vdev=dlb2_event,qid_depth_thresh=qid:<threshold_value>

It should be dlb_event. Right?