diff mbox series

[2/4] event/dlb: remove DLB V1 documentation

Message ID 1614618060-12773-3-git-send-email-timothy.mcdaniel@intel.com (mailing list archive)
State Changes Requested
Delegated to: Jerin Jacob
Headers show
Series Remove Support For DLB V1 | expand

Checks

Context Check Description
ci/checkpatch success coding style OK

Commit Message

McDaniel, Timothy March 1, 2021, 5 p.m. UTC
Support for DLB v1 is being removed from dpdk in 21.05.

Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
---
 doc/api/doxy-api-index.md      |   1 -
 doc/api/doxy-api.conf.in       |   1 -
 doc/guides/eventdevs/dlb.rst   | 341 ---------------------------------
 doc/guides/eventdevs/index.rst |   1 -
 4 files changed, 344 deletions(-)
 delete mode 100644 doc/guides/eventdevs/dlb.rst
diff mbox series

Patch

diff --git a/doc/api/doxy-api-index.md b/doc/api/doxy-api-index.md
index 748514e24..38376149c 100644
--- a/doc/api/doxy-api-index.md
+++ b/doc/api/doxy-api-index.md
@@ -55,7 +55,6 @@  The public API headers are grouped by topics:
   [dpaa2_cmdif]        (@ref rte_pmd_dpaa2_cmdif.h),
   [dpaa2_qdma]         (@ref rte_pmd_dpaa2_qdma.h),
   [crypto_scheduler]   (@ref rte_cryptodev_scheduler.h),
-  [dlb]                (@ref rte_pmd_dlb.h),
   [dlb2]               (@ref rte_pmd_dlb2.h)
 
 - **memory**:
diff --git a/doc/api/doxy-api.conf.in b/doc/api/doxy-api.conf.in
index 5c883b613..49d1c3ac4 100644
--- a/doc/api/doxy-api.conf.in
+++ b/doc/api/doxy-api.conf.in
@@ -7,7 +7,6 @@  USE_MDFILE_AS_MAINPAGE  = @TOPDIR@/doc/api/doxy-api-index.md
 INPUT                   = @TOPDIR@/doc/api/doxy-api-index.md \
                           @TOPDIR@/drivers/bus/vdev \
                           @TOPDIR@/drivers/crypto/scheduler \
-                          @TOPDIR@/drivers/event/dlb \
                           @TOPDIR@/drivers/event/dlb2 \
                           @TOPDIR@/drivers/mempool/dpaa2 \
                           @TOPDIR@/drivers/net/ark \
diff --git a/doc/guides/eventdevs/dlb.rst b/doc/guides/eventdevs/dlb.rst
deleted file mode 100644
index d44afcdcf..000000000
--- a/doc/guides/eventdevs/dlb.rst
+++ /dev/null
@@ -1,341 +0,0 @@ 
-..  SPDX-License-Identifier: BSD-3-Clause
-    Copyright(c) 2020 Intel Corporation.
-
-Driver for the Intel® Dynamic Load Balancer (DLB)
-=================================================
-
-The DPDK dlb poll mode driver supports the Intel® Dynamic Load Balancer.
-
-Prerequisites
--------------
-
-Follow the DPDK :ref:`Getting Started Guide for Linux <linux_gsg>` to setup
-the basic DPDK environment.
-
-Configuration
--------------
-
-The DLB PF PMD is a user-space PMD that uses VFIO to gain direct
-device access. To use this operation mode, the PCIe PF device must be bound
-to a DPDK-compatible VFIO driver, such as vfio-pci.
-
-Eventdev API Notes
-------------------
-
-The DLB provides the functions of a DPDK event device; specifically, it
-supports atomic, ordered, and parallel scheduling events from queues to ports.
-However, the DLB hardware is not a perfect match to the eventdev API. Some DLB
-features are abstracted by the PMD (e.g. directed ports), some are only
-accessible as vdev command-line parameters, and certain eventdev features are
-not supported (e.g. the event flow ID is not maintained during scheduling).
-
-In general the dlb PMD is designed for ease-of-use and does not require a
-detailed understanding of the hardware, but these details are important when
-writing high-performance code. This section describes the places where the
-eventdev API and DLB misalign.
-
-Scheduling Domain Configuration
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-There are 32 scheduling domainis the DLB.
-When one is configured, it allocates load-balanced and
-directed queues, ports, credits, and other hardware resources. Some
-resource allocations are user-controlled -- the number of queues, for example
--- and others, like credit pools (one directed and one load-balanced pool per
-scheduling domain), are not.
-
-The DLB is a closed system eventdev, and as such the ``nb_events_limit`` device
-setup argument and the per-port ``new_event_threshold`` argument apply as
-defined in the eventdev header file. The limit is applied to all enqueues,
-regardless of whether it will consume a directed or load-balanced credit.
-
-Reconfiguration
-~~~~~~~~~~~~~~~
-
-The Eventdev API allows one to reconfigure a device, its ports, and its queues
-by first stopping the device, calling the configuration function(s), then
-restarting the device. The DLB does not support configuring an individual queue
-or port without first reconfiguring the entire device, however, so there are
-certain reconfiguration sequences that are valid in the eventdev API but not
-supported by the PMD.
-
-Specifically, the PMD supports the following configuration sequence:
-1. Configure and start the device
-2. Stop the device
-3. (Optional) Reconfigure the device
-4. (Optional) If step 3 is run:
-
-   a. Setup queue(s). The reconfigured queue(s) lose their previous port links.
-   b. The reconfigured port(s) lose their previous queue links.
-
-5. (Optional, only if steps 4a and 4b are run) Link port(s) to queue(s)
-6. Restart the device. If the device is reconfigured in step 3 but one or more
-   of its ports or queues are not, the PMD will apply their previous
-   configuration (including port->queue links) at this time.
-
-The PMD does not support the following configuration sequences:
-1. Configure and start the device
-2. Stop the device
-3. Setup queue or setup port
-4. Start the device
-
-This sequence is not supported because the event device must be reconfigured
-before its ports or queues can be.
-
-Load-Balanced Queues
-~~~~~~~~~~~~~~~~~~~~
-
-A load-balanced queue can support atomic and ordered scheduling, or atomic and
-unordered scheduling, but not atomic and unordered and ordered scheduling. A
-queue's scheduling types are controlled by the event queue configuration.
-
-If the user sets the ``RTE_EVENT_QUEUE_CFG_ALL_TYPES`` flag, the
-``nb_atomic_order_sequences`` determines the supported scheduling types.
-With non-zero ``nb_atomic_order_sequences``, the queue is configured for atomic
-and ordered scheduling. In this case, ``RTE_SCHED_TYPE_PARALLEL`` scheduling is
-supported by scheduling those events as ordered events.  Note that when the
-event is dequeued, its sched_type will be ``RTE_SCHED_TYPE_ORDERED``. Else if
-``nb_atomic_order_sequences`` is zero, the queue is configured for atomic and
-unordered scheduling. In this case, ``RTE_SCHED_TYPE_ORDERED`` is unsupported.
-
-If the ``RTE_EVENT_QUEUE_CFG_ALL_TYPES`` flag is not set, schedule_type
-dictates the queue's scheduling type.
-
-The ``nb_atomic_order_sequences`` queue configuration field sets the ordered
-queue's reorder buffer size.  DLB has 4 groups of ordered queues, where each
-group is configured to contain either 1 queue with 1024 reorder entries, 2
-queues with 512 reorder entries, and so on down to 32 queues with 32 entries.
-
-When a load-balanced queue is created, the PMD will configure a new sequence
-number group on-demand if num_sequence_numbers does not match a pre-existing
-group with available reorder buffer entries. If all sequence number groups are
-in use, no new group will be created and queue configuration will fail. (Note
-that when the PMD is used with a virtual DLB device, it cannot change the
-sequence number configuration.)
-
-The queue's ``nb_atomic_flows`` parameter is ignored by the DLB PMD, because
-the DLB does not limit the number of flows a queue can track. In the DLB, all
-load-balanced queues can use the full 16-bit flow ID range.
-
-Load-balanced and Directed Ports
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-DLB ports come in two flavors: load-balanced and directed. The eventdev API
-does not have the same concept, but it has a similar one: ports and queues that
-are singly-linked (i.e. linked to a single queue or port, respectively).
-
-The ``rte_event_dev_info_get()`` function reports the number of available
-event ports and queues (among other things). For the DLB PMD, max_event_ports
-and max_event_queues report the number of available load-balanced ports and
-queues, and max_single_link_event_port_queue_pairs reports the number of
-available directed ports and queues.
-
-When a scheduling domain is created in ``rte_event_dev_configure()``, the user
-specifies ``nb_event_ports`` and ``nb_single_link_event_port_queues``, which
-control the total number of ports (load-balanced and directed) and the number
-of directed ports. Hence, the number of requested load-balanced ports is
-``nb_event_ports - nb_single_link_event_ports``. The ``nb_event_queues`` field
-specifies the total number of queues (load-balanced and directed). The number
-of directed queues comes from ``nb_single_link_event_port_queues``, since
-directed ports and queues come in pairs.
-
-When a port is setup, the ``RTE_EVENT_PORT_CFG_SINGLE_LINK`` flag determines
-whether it should be configured as a directed (the flag is set) or a
-load-balanced (the flag is unset) port. Similarly, the
-``RTE_EVENT_QUEUE_CFG_SINGLE_LINK`` queue configuration flag controls
-whether it is a directed or load-balanced queue.
-
-Load-balanced ports can only be linked to load-balanced queues, and directed
-ports can only be linked to directed queues. Furthermore, directed ports can
-only be linked to a single directed queue (and vice versa), and that link
-cannot change after the eventdev is started.
-
-The eventdev API does not have a directed scheduling type. To support directed
-traffic, the dlb PMD detects when an event is being sent to a directed queue
-and overrides its scheduling type. Note that the originally selected scheduling
-type (atomic, ordered, or parallel) is not preserved, and an event's sched_type
-will be set to ``RTE_SCHED_TYPE_ATOMIC`` when it is dequeued from a directed
-port.
-
-Flow ID
-~~~~~~~
-
-The flow ID field is not preserved in the event when it is scheduled in the
-DLB, because the DLB hardware control word format does not have sufficient
-space to preserve every event field. As a result, the flow ID specified with
-the enqueued event will not be in the dequeued event. If this field is
-required, the application should pass it through an out-of-band path (for
-example in the mbuf's udata64 field, if the event points to an mbuf) or
-reconstruct the flow ID after receiving the event.
-
-Also, the DLB hardware control word supports a 16-bit flow ID. Since struct
-rte_event's flow_id field is 20 bits, the DLB PMD drops the most significant
-four bits from the event's flow ID.
-
-Hardware Credits
-~~~~~~~~~~~~~~~~
-
-DLB uses a hardware credit scheme to prevent software from overflowing hardware
-event storage, with each unit of storage represented by a credit. A port spends
-a credit to enqueue an event, and hardware refills the ports with credits as the
-events are scheduled to ports. Refills come from credit pools, and each port is
-a member of a load-balanced credit pool and a directed credit pool. The
-load-balanced credits are used to enqueue to load-balanced queues, and directed
-credits are used for directed queues.
-
-A DLB eventdev contains one load-balanced and one directed credit pool. These
-pools' sizes are controlled by the nb_events_limit field in struct
-rte_event_dev_config. The load-balanced pool is sized to contain
-nb_events_limit credits, and the directed pool is sized to contain
-nb_events_limit/4 credits. The directed pool size can be overridden with the
-num_dir_credits vdev argument, like so:
-
-    .. code-block:: console
-
-       --vdev=dlb1_event,num_dir_credits=<value>
-
-This can be used if the default allocation is too low or too high for the
-specific application needs. The PMD also supports a vdev arg that limits the
-max_num_events reported by rte_event_dev_info_get():
-
-    .. code-block:: console
-
-       --vdev=dlb1_event,max_num_events=<value>
-
-By default, max_num_events is reported as the total available load-balanced
-credits. If multiple DLB-based applications are being used, it may be desirable
-to control how many load-balanced credits each application uses, particularly
-when application(s) are written to configure nb_events_limit equal to the
-reported max_num_events.
-
-Each port is a member of both credit pools. A port's credit allocation is
-defined by its low watermark, high watermark, and refill quanta. These three
-parameters are calculated by the dlb PMD like so:
-
-- The load-balanced high watermark is set to the port's enqueue_depth.
-  The directed high watermark is set to the minimum of the enqueue_depth and
-  the directed pool size divided by the total number of ports.
-- The refill quanta is set to half the high watermark.
-- The low watermark is set to the minimum of 16 and the refill quanta.
-
-When the eventdev is started, each port is pre-allocated a high watermark's
-worth of credits. For example, if an eventdev contains four ports with enqueue
-depths of 32 and a load-balanced credit pool size of 4096, each port will start
-with 32 load-balanced credits, and there will be 3968 credits available to
-replenish the ports. Thus, a single port is not capable of enqueueing up to the
-nb_events_limit (without any events being dequeued), since the other ports are
-retaining their initial credit allocation; in short, all ports must enqueue in
-order to reach the limit.
-
-If a port attempts to enqueue and has no credits available, the enqueue
-operation will fail and the application must retry the enqueue. Credits are
-replenished asynchronously by the DLB hardware.
-
-Software Credits
-~~~~~~~~~~~~~~~~
-
-The DLB is a "closed system" event dev, and the DLB PMD layers a software
-credit scheme on top of the hardware credit scheme in order to comply with
-the per-port backpressure described in the eventdev API.
-
-The DLB's hardware scheme is local to a queue/pipeline stage: a port spends a
-credit when it enqueues to a queue, and credits are later replenished after the
-events are dequeued and released.
-
-In the software credit scheme, a credit is consumed when a new (.op =
-RTE_EVENT_OP_NEW) event is injected into the system, and the credit is
-replenished when the event is released from the system (either explicitly with
-RTE_EVENT_OP_RELEASE or implicitly in dequeue_burst()).
-
-In this model, an event is "in the system" from its first enqueue into eventdev
-until it is last dequeued. If the event goes through multiple event queues, it
-is still considered "in the system" while a worker thread is processing it.
-
-A port will fail to enqueue if the number of events in the system exceeds its
-``new_event_threshold`` (specified at port setup time). A port will also fail
-to enqueue if it lacks enough hardware credits to enqueue; load-balanced
-credits are used to enqueue to a load-balanced queue, and directed credits are
-used to enqueue to a directed queue.
-
-The out-of-credit situations are typically transient, and an eventdev
-application using the DLB ought to retry its enqueues if they fail.
-If enqueue fails, DLB PMD sets rte_errno as follows:
-
-- -ENOSPC: Credit exhaustion (either hardware or software)
-- -EINVAL: Invalid argument, such as port ID, queue ID, or sched_type.
-
-Depending on the pipeline the application has constructed, it's possible to
-enter a credit deadlock scenario wherein the worker thread lacks the credit
-to enqueue an event, and it must dequeue an event before it can recover the
-credit. If the worker thread retries its enqueue indefinitely, it will not
-make forward progress. Such deadlock is possible if the application has event
-"loops", in which an event in dequeued from queue A and later enqueued back to
-queue A.
-
-Due to this, workers should stop retrying after a time, release the events it
-is attempting to enqueue, and dequeue more events. It is important that the
-worker release the events and don't simply set them aside to retry the enqueue
-again later, because the port has limited history list size (by default, twice
-the port's dequeue_depth).
-
-Priority
-~~~~~~~~
-
-The DLB supports event priority and per-port queue service priority, as
-described in the eventdev header file. The DLB does not support 'global' event
-queue priority established at queue creation time.
-
-DLB supports 8 event and queue service priority levels. For both priority
-types, the PMD uses the upper three bits of the priority field to determine the
-DLB priority, discarding the 5 least significant bits. The 5 least significant
-event priority bits are not preserved when an event is enqueued.
-
-Atomic Inflights Allocation
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-In the last stage prior to scheduling an atomic event to a CQ, DLB 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
-
-Deferred Scheduling
-~~~~~~~~~~~~~~~~~~~
-
-The DLB 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 DLB 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
-
diff --git a/doc/guides/eventdevs/index.rst b/doc/guides/eventdevs/index.rst
index f5b69b39d..738788d9e 100644
--- a/doc/guides/eventdevs/index.rst
+++ b/doc/guides/eventdevs/index.rst
@@ -11,7 +11,6 @@  application through the eventdev API.
     :maxdepth: 2
     :numbered:
 
-    dlb
     dlb2
     dpaa
     dpaa2