[v2,01/22] event/dlb2: add documentation and meson build infrastructure
diff mbox series

Message ID 1602958879-8558-2-git-send-email-timothy.mcdaniel@intel.com
State Superseded
Delegated to: Jerin Jacob
Headers show
Series
  • Add DLB2 PMD
Related show

Checks

Context Check Description
ci/Performance-Testing fail build patch failure
ci/checkpatch warning coding style issues

Commit Message

McDaniel, Timothy Oct. 17, 2020, 6:20 p.m. UTC
Adds the meson build infrastructure, which includes
compile-time constants in rte_config.h. DLB2 is
only supported on Linux X86 platforms at this time.

Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
Reviewed-by: Gage Eads <gage.eads@intel.com>
---
 config/rte_config.h                               |   7 +
 doc/guides/eventdevs/dlb2.rst                     | 330 ++++++++++++++++++++++
 doc/guides/eventdevs/index.rst                    |   1 +
 drivers/event/dlb2/meson.build                    |   7 +
 drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
 drivers/event/meson.build                         |   3 +
 6 files changed, 351 insertions(+)
 create mode 100644 doc/guides/eventdevs/dlb2.rst
 create mode 100644 drivers/event/dlb2/meson.build
 create mode 100644 drivers/event/dlb2/rte_pmd_dlb2_event_version.map

Comments

Jerin Jacob Oct. 18, 2020, 8:48 a.m. UTC | #1
On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
<timothy.mcdaniel@intel.com> wrote:
>
> Adds the meson build infrastructure, which includes
> compile-time constants in rte_config.h. DLB2 is
> only supported on Linux X86 platforms at this time.
>
> Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> Reviewed-by: Gage Eads <gage.eads@intel.com>
> ---
>  config/rte_config.h                               |   7 +
>  doc/guides/eventdevs/dlb2.rst                     | 330 ++++++++++++++++++++++
>  doc/guides/eventdevs/index.rst                    |   1 +
>  drivers/event/dlb2/meson.build                    |   7 +
>  drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
>  drivers/event/meson.build                         |   3 +
>  6 files changed, 351 insertions(+)
>  create mode 100644 doc/guides/eventdevs/dlb2.rst
>  create mode 100644 drivers/event/dlb2/meson.build
>  create mode 100644 drivers/event/dlb2/rte_pmd_dlb2_event_version.map
>
> diff --git a/config/rte_config.h b/config/rte_config.h
> index 0bae630..fd1b3c3 100644
> --- a/config/rte_config.h
> +++ b/config/rte_config.h
> @@ -131,4 +131,11 @@
>  /* QEDE PMD defines */
>  #define RTE_LIBRTE_QEDE_FW ""
>
> +/* DLB2 defines */
> +#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
> +#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
> +#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
> +#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
> +#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256

We are going way with GLOBAL compile time options for drivers.
I think,  we should move to driver-specific folder not pollute top
level config file.
@Richardson, Bruce  @Thomas Monjalon  Thoughts?


> +
>  #endif /* _RTE_CONFIG_H_ */
> diff --git a/doc/guides/eventdevs/dlb2.rst b/doc/guides/eventdevs/dlb2.rst
> new file mode 100644
> index 0000000..fa8d6dd
> --- /dev/null
> +++ b/doc/guides/eventdevs/dlb2.rst
> @@ -0,0 +1,330 @@
> +..  SPDX-License-Identifier: BSD-3-Clause
> +    Copyright(c) 2020 Intel Corporation.
> +
> +Driver for the Intel® Dynamic Load Balancer (DLB2)
> +==================================================
> +
> +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 DLB2 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 DLB2 provides the functions of a DPDK event device; specifically, it
> +supports atomic, ordered, and parallel scheduling events from queues to ports.
> +However, the DLB2 hardware is not a perfect match to the eventdev API. Some DLB2
> +features are abstracted by the PMD such as directed ports.
> +
> +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 DLB2 misalign.
> +
> +Scheduling Domain Configuration
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +There are 32 scheduling domainis the DLB2.
> +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 DLB2 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.
> +
> +Load-balanced and Directed Ports
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +DLB2 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 DLB2 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 preserved in the event when it is scheduled in the
> +DLB2.
> +
> +Hardware Credits
> +~~~~~~~~~~~~~~~~
> +
> +DLB2 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 DLB2 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 DLB2-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 DLB2 hardware.
> +
> +Software Credits
> +~~~~~~~~~~~~~~~~
> +
> +The DLB2 is a "closed system" event dev, and the DLB2 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 DLB2'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 DLB2 ought to retry its enqueues if they fail.
> +If enqueue fails, DLB2 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 DLB2 supports event priority and per-port queue service priority, as
> +described in the eventdev header file. The DLB2 does not support 'global' event
> +queue priority established at queue creation time.
> +
> +DLB2 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
> +DLB2 priority, discarding the 5 least significant bits. The 5 least significant
> +event priority bits are not preserved when an event is enqueued.
> +
> +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.  DLB2 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 DLB2 device, it cannot change the
> +sequence number configuration.)
> +
> +The queue's ``nb_atomic_flows`` parameter is ignored by the DLB2 PMD, because
> +the DLB2 does not limit the number of flows a queue can track. In the DLB2, all
> +load-balanced queues can use the full 16-bit flow ID range.
> +
> +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 DLB2 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.
> +
> +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
> +
> +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
> +


Please move the doc changes to whichever patch that introduces this change,


> diff --git a/doc/guides/eventdevs/index.rst b/doc/guides/eventdevs/index.rst
> index bb66a5e..55d5ba8 100644
> --- a/doc/guides/eventdevs/index.rst
> +++ b/doc/guides/eventdevs/index.rst
> @@ -18,3 +18,4 @@ application through the eventdev API.
>      octeontx
>      octeontx2
>      opdl
> +    dlb2
> diff --git a/drivers/event/dlb2/meson.build b/drivers/event/dlb2/meson.build
> new file mode 100644
> index 0000000..54ba2c8
> --- /dev/null
> +++ b/drivers/event/dlb2/meson.build
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2019-2020 Intel Corporation
> +
> +sources = files(
> +)
> +
> +deps += ['mbuf', 'mempool', 'ring', 'pci', 'bus_pci']
> diff --git a/drivers/event/dlb2/rte_pmd_dlb2_event_version.map b/drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> new file mode 100644
> index 0000000..299ae63
> --- /dev/null
> +++ b/drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> @@ -0,0 +1,3 @@
> +DPDK_21.0 {
> +       local: *;
> +};
> diff --git a/drivers/event/meson.build b/drivers/event/meson.build"
> index ebe76a7..01d3b59 100644
> --- a/drivers/event/meson.build
> +++ b/drivers/event/meson.build
> @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and cc.version().version_compare('<4.8.6') and
>         dpdk_conf.has('RTE_ARCH_ARM64'))
>         drivers += 'octeontx'
>  endif
> +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> +        drivers += 'dlb2'
> +endif

Please add the message in "Content Skipped" section,
Reference: grep "reason" in drivers/vdpa/mlx5/meson.build





>  std_deps = ['eventdev', 'kvargs']
>  config_flag_fmt = 'RTE_LIBRTE_@0@_EVENTDEV_PMD'
>  driver_name_fmt = 'rte_pmd_@0@_event'
> --
> 2.6.4
>
Bruce Richardson Oct. 19, 2020, 8:33 a.m. UTC | #2
On Sun, Oct 18, 2020 at 02:18:32PM +0530, Jerin Jacob wrote:
> On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> <timothy.mcdaniel@intel.com> wrote:
> >
> > Adds the meson build infrastructure, which includes
> > compile-time constants in rte_config.h. DLB2 is
> > only supported on Linux X86 platforms at this time.
> >
> > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > ---
> >  config/rte_config.h                               |   7 +
> >  doc/guides/eventdevs/dlb2.rst                     | 330 ++++++++++++++++++++++
> >  doc/guides/eventdevs/index.rst                    |   1 +
> >  drivers/event/dlb2/meson.build                    |   7 +
> >  drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
> >  drivers/event/meson.build                         |   3 +
> >  6 files changed, 351 insertions(+)
> >  create mode 100644 doc/guides/eventdevs/dlb2.rst
> >  create mode 100644 drivers/event/dlb2/meson.build
> >  create mode 100644 drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> >
> > diff --git a/config/rte_config.h b/config/rte_config.h
> > index 0bae630..fd1b3c3 100644
> > --- a/config/rte_config.h
> > +++ b/config/rte_config.h
> > @@ -131,4 +131,11 @@
> >  /* QEDE PMD defines */
> >  #define RTE_LIBRTE_QEDE_FW ""
> >
> > +/* DLB2 defines */
> > +#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
> > +#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
> > +#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
> > +#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
> > +#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
> 
> We are going way with GLOBAL compile time options for drivers.
> I think,  we should move to driver-specific folder not pollute top
> level config file.
> @Richardson, Bruce  @Thomas Monjalon  Thoughts?
>
Yes, we do need a better way to pass driver-specific build config options.
How likely is it that the user may want to tweak these values? If it's not
likely having them just as regular defines in the driver folder may be
better, though they are not particularly problematic in rte_config.h given
the number of other values already there.
 
> 
> > +
<snip>
> > --- a/drivers/event/meson.build
> > +++ b/drivers/event/meson.build
> > @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and cc.version().version_compare('<4.8.6') and
> >         dpdk_conf.has('RTE_ARCH_ARM64'))
> >         drivers += 'octeontx'
> >  endif
> > +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> > +        drivers += 'dlb2'
> > +endif
> 
> Please add the message in "Content Skipped" section,
> Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> 

The octeontx case is also wrong in this file, IMHO. Rather than checking
things in the event level and adding things to the list, the list should
just be static. If something should be optionally compiled, then check the
conditions in the driver meson.build file itself and add "build=false" to
disable, setting "reason" to the cause of it being disabled. This keeps all
the logic about a driver in the other file, rather than someone having to
look in multiple places for why something is or isn't getting built
properly.

Regards,
/Bruce
Kinsella, Ray Oct. 19, 2020, 9:59 a.m. UTC | #3
On 17/10/2020 19:20, Timothy McDaniel wrote:
> Adds the meson build infrastructure, which includes
> compile-time constants in rte_config.h. DLB2 is
> only supported on Linux X86 platforms at this time.
> 
> Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> Reviewed-by: Gage Eads <gage.eads@intel.com>
> ---
>  config/rte_config.h                               |   7 +
>  doc/guides/eventdevs/dlb2.rst                     | 330 ++++++++++++++++++++++
>  doc/guides/eventdevs/index.rst                    |   1 +
>  drivers/event/dlb2/meson.build                    |   7 +
>  drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
>  drivers/event/meson.build                         |   3 +
>  6 files changed, 351 insertions(+)
>  create mode 100644 doc/guides/eventdevs/dlb2.rst
>  create mode 100644 drivers/event/dlb2/meson.build
>  create mode 100644 drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> 
> diff --git a/config/rte_config.h b/config/rte_config.h
> index 0bae630..fd1b3c3 100644
> --- a/config/rte_config.h
> +++ b/config/rte_config.h
> @@ -131,4 +131,11 @@
>  /* QEDE PMD defines */
>  #define RTE_LIBRTE_QEDE_FW ""
>  
> +/* DLB2 defines */
> +#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
> +#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
> +#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
> +#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
> +#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
> +
>  #endif /* _RTE_CONFIG_H_ */
> diff --git a/doc/guides/eventdevs/dlb2.rst b/doc/guides/eventdevs/dlb2.rst
> new file mode 100644
> index 0000000..fa8d6dd
> --- /dev/null
> +++ b/doc/guides/eventdevs/dlb2.rst
> @@ -0,0 +1,330 @@
> +..  SPDX-License-Identifier: BSD-3-Clause
> +    Copyright(c) 2020 Intel Corporation.
> +
> +Driver for the Intel® Dynamic Load Balancer (DLB2)
> +==================================================
> +
> +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 DLB2 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 DLB2 provides the functions of a DPDK event device; specifically, it
> +supports atomic, ordered, and parallel scheduling events from queues to ports.
> +However, the DLB2 hardware is not a perfect match to the eventdev API. Some DLB2
> +features are abstracted by the PMD such as directed ports.
> +
> +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 DLB2 misalign.
> +
> +Scheduling Domain Configuration
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +There are 32 scheduling domainis the DLB2.
> +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 DLB2 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.
> +
> +Load-balanced and Directed Ports
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +DLB2 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 DLB2 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 preserved in the event when it is scheduled in the
> +DLB2.
> +
> +Hardware Credits
> +~~~~~~~~~~~~~~~~
> +
> +DLB2 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 DLB2 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 DLB2-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 DLB2 hardware.
> +
> +Software Credits
> +~~~~~~~~~~~~~~~~
> +
> +The DLB2 is a "closed system" event dev, and the DLB2 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 DLB2'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 DLB2 ought to retry its enqueues if they fail.
> +If enqueue fails, DLB2 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 DLB2 supports event priority and per-port queue service priority, as
> +described in the eventdev header file. The DLB2 does not support 'global' event
> +queue priority established at queue creation time.
> +
> +DLB2 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
> +DLB2 priority, discarding the 5 least significant bits. The 5 least significant
> +event priority bits are not preserved when an event is enqueued.
> +
> +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.  DLB2 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 DLB2 device, it cannot change the
> +sequence number configuration.)
> +
> +The queue's ``nb_atomic_flows`` parameter is ignored by the DLB2 PMD, because
> +the DLB2 does not limit the number of flows a queue can track. In the DLB2, all
> +load-balanced queues can use the full 16-bit flow ID range.
> +
> +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 DLB2 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.
> +
> +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
> +
> +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
> +
> diff --git a/doc/guides/eventdevs/index.rst b/doc/guides/eventdevs/index.rst
> index bb66a5e..55d5ba8 100644
> --- a/doc/guides/eventdevs/index.rst
> +++ b/doc/guides/eventdevs/index.rst
> @@ -18,3 +18,4 @@ application through the eventdev API.
>      octeontx
>      octeontx2
>      opdl
> +    dlb2
> diff --git a/drivers/event/dlb2/meson.build b/drivers/event/dlb2/meson.build
> new file mode 100644
> index 0000000..54ba2c8
> --- /dev/null
> +++ b/drivers/event/dlb2/meson.build
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2019-2020 Intel Corporation
> +
> +sources = files(
> +)
> +
> +deps += ['mbuf', 'mempool', 'ring', 'pci', 'bus_pci']
> diff --git a/drivers/event/dlb2/rte_pmd_dlb2_event_version.map b/drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> new file mode 100644
> index 0000000..299ae63
> --- /dev/null
> +++ b/drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> @@ -0,0 +1,3 @@
> +DPDK_21.0 {

Should be DPDK_21

> +	local: *;
> +};
> diff --git a/drivers/event/meson.build b/drivers/event/meson.build
> index ebe76a7..01d3b59 100644
> --- a/drivers/event/meson.build
> +++ b/drivers/event/meson.build
> @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and cc.version().version_compare('<4.8.6') and
>  	dpdk_conf.has('RTE_ARCH_ARM64'))
>  	drivers += 'octeontx'
>  endif
> +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> +        drivers += 'dlb2'
> +endif
>  std_deps = ['eventdev', 'kvargs']
>  config_flag_fmt = 'RTE_LIBRTE_@0@_EVENTDEV_PMD'
>  driver_name_fmt = 'rte_pmd_@0@_event'
>
McDaniel, Timothy Oct. 20, 2020, 2:07 p.m. UTC | #4
> -----Original Message-----
> From: Jerin Jacob <jerinjacobk@gmail.com>
> Sent: Sunday, October 18, 2020 3:49 AM
> To: McDaniel, Timothy <timothy.mcdaniel@intel.com>
> Cc: Richardson, Bruce <bruce.richardson@intel.com>; Mcnamara, John
> <john.mcnamara@intel.com>; Kovacevic, Marko
> <Marko.Kovacevic@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil Horman
> <nhorman@tuxdriver.com>; dpdk-dev <dev@dpdk.org>; Carrillo, Erik G
> <Erik.G.Carrillo@intel.com>; Eads, Gage <gage.eads@intel.com>; Van Haaren,
> Harry <harry.van.haaren@intel.com>; Jerin Jacob <jerinj@marvell.com>;
> Thomas Monjalon <thomas@monjalon.net>
> Subject: Re: [dpdk-dev] [PATCH v2 01/22] event/dlb2: add documentation and
> meson build infrastructure
> 
> On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> <timothy.mcdaniel@intel.com> wrote:
> >
> > Adds the meson build infrastructure, which includes
> > compile-time constants in rte_config.h. DLB2 is
> > only supported on Linux X86 platforms at this time.
> >
> > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > ---
> >  config/rte_config.h                               |   7 +
> >  doc/guides/eventdevs/dlb2.rst                     | 330 ++++++++++++++++++++++
> >  doc/guides/eventdevs/index.rst                    |   1 +
> >  drivers/event/dlb2/meson.build                    |   7 +
> >  drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
> >  drivers/event/meson.build                         |   3 +
> >  6 files changed, 351 insertions(+)
> >  create mode 100644 doc/guides/eventdevs/dlb2.rst
> >  create mode 100644 drivers/event/dlb2/meson.build
> >  create mode 100644 drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> >
> > diff --git a/config/rte_config.h b/config/rte_config.h
> > index 0bae630..fd1b3c3 100644
> > --- a/config/rte_config.h
> > +++ b/config/rte_config.h
> > @@ -131,4 +131,11 @@
> >  /* QEDE PMD defines */
> >  #define RTE_LIBRTE_QEDE_FW ""
> >
> > +/* DLB2 defines */
> > +#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
> > +#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
> > +#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
> > +#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
> > +#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
> 
> We are going way with GLOBAL compile time options for drivers.
> I think,  we should move to driver-specific folder not pollute top
> level config file.
> @Richardson, Bruce  @Thomas Monjalon  Thoughts?
> 
> 
> > +
> >  #endif /* _RTE_CONFIG_H_ */
> > diff --git a/doc/guides/eventdevs/dlb2.rst b/doc/guides/eventdevs/dlb2.rst
> > new file mode 100644
> > index 0000000..fa8d6dd
> > --- /dev/null
> > +++ b/doc/guides/eventdevs/dlb2.rst
> > @@ -0,0 +1,330 @@
> > +..  SPDX-License-Identifier: BSD-3-Clause
> > +    Copyright(c) 2020 Intel Corporation.
> > +
> > +Driver for the Intel® Dynamic Load Balancer (DLB2)
> > +==================================================
> > +
> > +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 DLB2 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 DLB2 provides the functions of a DPDK event device; specifically, it
> > +supports atomic, ordered, and parallel scheduling events from queues to
> ports.
> > +However, the DLB2 hardware is not a perfect match to the eventdev API.
> Some DLB2
> > +features are abstracted by the PMD such as directed ports.
> > +
> > +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 DLB2 misalign.
> > +
> > +Scheduling Domain Configuration
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > +
> > +There are 32 scheduling domainis the DLB2.
> > +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 DLB2 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.
> > +
> > +Load-balanced and Directed Ports
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > +
> > +DLB2 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 DLB2 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 preserved in the event when it is scheduled in the
> > +DLB2.
> > +
> > +Hardware Credits
> > +~~~~~~~~~~~~~~~~
> > +
> > +DLB2 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 DLB2 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 DLB2-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 DLB2 hardware.
> > +
> > +Software Credits
> > +~~~~~~~~~~~~~~~~
> > +
> > +The DLB2 is a "closed system" event dev, and the DLB2 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 DLB2'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 DLB2 ought to retry its enqueues if they fail.
> > +If enqueue fails, DLB2 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 DLB2 supports event priority and per-port queue service priority, as
> > +described in the eventdev header file. The DLB2 does not support 'global'
> event
> > +queue priority established at queue creation time.
> > +
> > +DLB2 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
> > +DLB2 priority, discarding the 5 least significant bits. The 5 least significant
> > +event priority bits are not preserved when an event is enqueued.
> > +
> > +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.  DLB2 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 DLB2 device, it cannot change the
> > +sequence number configuration.)
> > +
> > +The queue's ``nb_atomic_flows`` parameter is ignored by the DLB2 PMD,
> because
> > +the DLB2 does not limit the number of flows a queue can track. In the DLB2,
> all
> > +load-balanced queues can use the full 16-bit flow ID range.
> > +
> > +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 DLB2 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.
> > +
> > +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
> > +
> > +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
> > +
> 
> 
> Please move the doc changes to whichever patch that introduces this change,
> 
> 

Will do.


> 
> Please add the message in "Content Skipped" section,
> Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> 
> 
>

Will do
McDaniel, Timothy Oct. 20, 2020, 3:17 p.m. UTC | #5
> -----Original Message-----
> From: Bruce Richardson <bruce.richardson@intel.com>
> Sent: Monday, October 19, 2020 3:34 AM
> To: Jerin Jacob <jerinjacobk@gmail.com>
> Cc: McDaniel, Timothy <timothy.mcdaniel@intel.com>; Mcnamara, John
> <john.mcnamara@intel.com>; Kovacevic, Marko
> <Marko.Kovacevic@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil Horman
> <nhorman@tuxdriver.com>; dpdk-dev <dev@dpdk.org>; Carrillo, Erik G
> <Erik.G.Carrillo@intel.com>; Eads, Gage <gage.eads@intel.com>; Van Haaren,
> Harry <harry.van.haaren@intel.com>; Jerin Jacob <jerinj@marvell.com>;
> Thomas Monjalon <thomas@monjalon.net>
> Subject: Re: [dpdk-dev] [PATCH v2 01/22] event/dlb2: add documentation and
> meson build infrastructure
> 
> On Sun, Oct 18, 2020 at 02:18:32PM +0530, Jerin Jacob wrote:
> > On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> > <timothy.mcdaniel@intel.com> wrote:
> > >
> > > Adds the meson build infrastructure, which includes
> > > compile-time constants in rte_config.h. DLB2 is
> > > only supported on Linux X86 platforms at this time.
> > >
> > > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > > ---
> > >  config/rte_config.h                               |   7 +
> > >  doc/guides/eventdevs/dlb2.rst                     | 330 ++++++++++++++++++++++
> > >  doc/guides/eventdevs/index.rst                    |   1 +
> > >  drivers/event/dlb2/meson.build                    |   7 +
> > >  drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
> > >  drivers/event/meson.build                         |   3 +
> > >  6 files changed, 351 insertions(+)
> > >  create mode 100644 doc/guides/eventdevs/dlb2.rst
> > >  create mode 100644 drivers/event/dlb2/meson.build
> > >  create mode 100644 drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> > >
> > > diff --git a/config/rte_config.h b/config/rte_config.h
> > > index 0bae630..fd1b3c3 100644
> > > --- a/config/rte_config.h
> > > +++ b/config/rte_config.h
> > > @@ -131,4 +131,11 @@
> > >  /* QEDE PMD defines */
> > >  #define RTE_LIBRTE_QEDE_FW ""
> > >
> > > +/* DLB2 defines */
> > > +#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
> > > +#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
> > > +#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
> > > +#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
> > > +#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
> >
> > We are going way with GLOBAL compile time options for drivers.
> > I think,  we should move to driver-specific folder not pollute top
> > level config file.
> > @Richardson, Bruce  @Thomas Monjalon  Thoughts?
> >
> Yes, we do need a better way to pass driver-specific build config options.
> How likely is it that the user may want to tweak these values? If it's not
> likely having them just as regular defines in the driver folder may be
> better, though they are not particularly problematic in rte_config.h given
> the number of other values already there.
> 
> >
> > > +
> <snip>
> > > --- a/drivers/event/meson.build
> > > +++ b/drivers/event/meson.build
> > > @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and
> cc.version().version_compare('<4.8.6') and
> > >         dpdk_conf.has('RTE_ARCH_ARM64'))
> > >         drivers += 'octeontx'
> > >  endif
> > > +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> > > +        drivers += 'dlb2'
> > > +endif
> >
> > Please add the message in "Content Skipped" section,
> > Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> >
> 
> The octeontx case is also wrong in this file, IMHO. Rather than checking
> things in the event level and adding things to the list, the list should
> just be static. If something should be optionally compiled, then check the
> conditions in the driver meson.build file itself and add "build=false" to
> disable, setting "reason" to the cause of it being disabled. This keeps all
> the logic about a driver in the other file, rather than someone having to
> look in multiple places for why something is or isn't getting built
> properly.
> 
> Regards,
> /Bruce

Due to time constraints, I would prefer to take these issues up in a future release.
Thomas Monjalon Oct. 20, 2020, 3:20 p.m. UTC | #6
20/10/2020 17:17, McDaniel, Timothy:
> From: Bruce Richardson <bruce.richardson@intel.com>
> > On Sun, Oct 18, 2020 at 02:18:32PM +0530, Jerin Jacob wrote:
> > > On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> > > <timothy.mcdaniel@intel.com> wrote:
> > > >
> > > > Adds the meson build infrastructure, which includes
> > > > compile-time constants in rte_config.h. DLB2 is
> > > > only supported on Linux X86 platforms at this time.
> > > >
> > > > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > > > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > > > ---
> > > > --- a/drivers/event/meson.build
> > > > +++ b/drivers/event/meson.build
> > > > @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and
> > cc.version().version_compare('<4.8.6') and
> > > >         dpdk_conf.has('RTE_ARCH_ARM64'))
> > > >         drivers += 'octeontx'
> > > >  endif
> > > > +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> > > > +        drivers += 'dlb2'
> > > > +endif
> > >
> > > Please add the message in "Content Skipped" section,
> > > Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> > >
> > 
> > The octeontx case is also wrong in this file, IMHO. Rather than checking
> > things in the event level and adding things to the list, the list should
> > just be static. If something should be optionally compiled, then check the
> > conditions in the driver meson.build file itself and add "build=false" to
> > disable, setting "reason" to the cause of it being disabled. This keeps all
> > the logic about a driver in the other file, rather than someone having to
> > look in multiple places for why something is or isn't getting built
> > properly.
> > 
> > Regards,
> > /Bruce
> 
> Due to time constraints, I would prefer to take these issues up in a future release.

If you have strong time constraints to complete everything,
then it is better to postpone the feature to the next release.
McDaniel, Timothy Oct. 20, 2020, 3:33 p.m. UTC | #7
> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Tuesday, October 20, 2020 10:21 AM
> To: McDaniel, Timothy <timothy.mcdaniel@intel.com>; Eads, Gage
> <gage.eads@intel.com>
> Cc: Richardson, Bruce <bruce.richardson@intel.com>; Jerin Jacob
> <jerinjacobk@gmail.com>; Mcnamara, John <john.mcnamara@intel.com>;
> Kovacevic, Marko <marko.kovacevic@intel.com>; Ray Kinsella
> <mdr@ashroe.eu>; Neil Horman <nhorman@tuxdriver.com>; dpdk-dev
> <dev@dpdk.org>; Carrillo, Erik G <erik.g.carrillo@intel.com>; Van Haaren, Harry
> <harry.van.haaren@intel.com>; Jerin Jacob <jerinj@marvell.com>;
> david.marchand@redhat.com
> Subject: Re: [dpdk-dev] [PATCH v2 01/22] event/dlb2: add documentation and
> meson build infrastructure
> 
> 20/10/2020 17:17, McDaniel, Timothy:
> > From: Bruce Richardson <bruce.richardson@intel.com>
> > > On Sun, Oct 18, 2020 at 02:18:32PM +0530, Jerin Jacob wrote:
> > > > On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> > > > <timothy.mcdaniel@intel.com> wrote:
> > > > >
> > > > > Adds the meson build infrastructure, which includes
> > > > > compile-time constants in rte_config.h. DLB2 is
> > > > > only supported on Linux X86 platforms at this time.
> > > > >
> > > > > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > > > > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > > > > ---
> > > > > --- a/drivers/event/meson.build
> > > > > +++ b/drivers/event/meson.build
> > > > > @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and
> > > cc.version().version_compare('<4.8.6') and
> > > > >         dpdk_conf.has('RTE_ARCH_ARM64'))
> > > > >         drivers += 'octeontx'
> > > > >  endif
> > > > > +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> > > > > +        drivers += 'dlb2'
> > > > > +endif
> > > >
> > > > Please add the message in "Content Skipped" section,
> > > > Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> > > >
> > >
> > > The octeontx case is also wrong in this file, IMHO. Rather than checking
> > > things in the event level and adding things to the list, the list should
> > > just be static. If something should be optionally compiled, then check the
> > > conditions in the driver meson.build file itself and add "build=false" to
> > > disable, setting "reason" to the cause of it being disabled. This keeps all
> > > the logic about a driver in the other file, rather than someone having to
> > > look in multiple places for why something is or isn't getting built
> > > properly.
> > >
> > > Regards,
> > > /Bruce
> >
> > Due to time constraints, I would prefer to take these issues up in a future
> release.
> 
> If you have strong time constraints to complete everything,
> then it is better to postpone the feature to the next release.
> 

You read too much into my comment. 
My point is that there does not seem to be community consensus on this issue,
so why are we debating it at this point in the release cycle.  There are plenty of examples
doing exactly what I am doing.
Bruce Richardson Oct. 20, 2020, 3:34 p.m. UTC | #8
On Tue, Oct 20, 2020 at 04:17:13PM +0100, McDaniel, Timothy wrote:
> 
> 
> > -----Original Message-----
> > From: Bruce Richardson <bruce.richardson@intel.com>
> > Sent: Monday, October 19, 2020 3:34 AM
> > To: Jerin Jacob <jerinjacobk@gmail.com>
> > Cc: McDaniel, Timothy <timothy.mcdaniel@intel.com>; Mcnamara, John
> > <john.mcnamara@intel.com>; Kovacevic, Marko
> > <Marko.Kovacevic@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil Horman
> > <nhorman@tuxdriver.com>; dpdk-dev <dev@dpdk.org>; Carrillo, Erik G
> > <Erik.G.Carrillo@intel.com>; Eads, Gage <gage.eads@intel.com>; Van Haaren,
> > Harry <harry.van.haaren@intel.com>; Jerin Jacob <jerinj@marvell.com>;
> > Thomas Monjalon <thomas@monjalon.net>
> > Subject: Re: [dpdk-dev] [PATCH v2 01/22] event/dlb2: add documentation and
> > meson build infrastructure
> >
> > On Sun, Oct 18, 2020 at 02:18:32PM +0530, Jerin Jacob wrote:
> > > On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> > > <timothy.mcdaniel@intel.com> wrote:
> > > >
> > > > Adds the meson build infrastructure, which includes
> > > > compile-time constants in rte_config.h. DLB2 is
> > > > only supported on Linux X86 platforms at this time.
> > > >
> > > > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > > > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > > > ---
> > > >  config/rte_config.h                               |   7 +
> > > >  doc/guides/eventdevs/dlb2.rst                     | 330 ++++++++++++++++++++++
> > > >  doc/guides/eventdevs/index.rst                    |   1 +
> > > >  drivers/event/dlb2/meson.build                    |   7 +
> > > >  drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
> > > >  drivers/event/meson.build                         |   3 +
> > > >  6 files changed, 351 insertions(+)
> > > >  create mode 100644 doc/guides/eventdevs/dlb2.rst
> > > >  create mode 100644 drivers/event/dlb2/meson.build
> > > >  create mode 100644 drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> > > >
> > > > diff --git a/config/rte_config.h b/config/rte_config.h
> > > > index 0bae630..fd1b3c3 100644
> > > > --- a/config/rte_config.h
> > > > +++ b/config/rte_config.h
> > > > @@ -131,4 +131,11 @@
> > > >  /* QEDE PMD defines */
> > > >  #define RTE_LIBRTE_QEDE_FW ""
> > > >
> > > > +/* DLB2 defines */
> > > > +#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
> > > > +#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
> > > > +#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
> > > > +#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
> > > > +#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
> > >
> > > We are going way with GLOBAL compile time options for drivers.
> > > I think,  we should move to driver-specific folder not pollute top
> > > level config file.
> > > @Richardson, Bruce  @Thomas Monjalon  Thoughts?
> > >
> > Yes, we do need a better way to pass driver-specific build config options.
> > How likely is it that the user may want to tweak these values? If it's not
> > likely having them just as regular defines in the driver folder may be
> > better, though they are not particularly problematic in rte_config.h given
> > the number of other values already there.
> >
> > >
> > > > +
> > <snip>
> > > > --- a/drivers/event/meson.build
> > > > +++ b/drivers/event/meson.build
> > > > @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and
> > cc.version().version_compare('<4.8.6') and
> > > >         dpdk_conf.has('RTE_ARCH_ARM64'))
> > > >         drivers += 'octeontx'
> > > >  endif
> > > > +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> > > > +        drivers += 'dlb2'
> > > > +endif
> > >
> > > Please add the message in "Content Skipped" section,
> > > Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> > >
> >
> > The octeontx case is also wrong in this file, IMHO. Rather than checking
> > things in the event level and adding things to the list, the list should
> > just be static. If something should be optionally compiled, then check the
> > conditions in the driver meson.build file itself and add "build=false" to
> > disable, setting "reason" to the cause of it being disabled. This keeps all
> > the logic about a driver in the other file, rather than someone having to
> > look in multiple places for why something is or isn't getting built
> > properly.
> >
> > Regards,
> > /Bruce
> 
> Due to time constraints, I would prefer to take these issues up in a future release.
>
I'm not suggesting you need to fix the existing octeon case, but it's easy
enough to add dlb2 to the existing list and add :

if not dpdk_conf.has('RTE_ARCH_X86_64') or not is_linux
	build = false
	reason = "..."
endif

to the dlb2 meson.build file.

Regards,
/Bruce
Bruce Richardson Oct. 20, 2020, 3:38 p.m. UTC | #9
On Tue, Oct 20, 2020 at 04:33:42PM +0100, McDaniel, Timothy wrote:
> 
> 
> > -----Original Message-----
> > From: Thomas Monjalon <thomas@monjalon.net>
> > Sent: Tuesday, October 20, 2020 10:21 AM
> > To: McDaniel, Timothy <timothy.mcdaniel@intel.com>; Eads, Gage
> > <gage.eads@intel.com>
> > Cc: Richardson, Bruce <bruce.richardson@intel.com>; Jerin Jacob
> > <jerinjacobk@gmail.com>; Mcnamara, John <john.mcnamara@intel.com>;
> > Kovacevic, Marko <marko.kovacevic@intel.com>; Ray Kinsella
> > <mdr@ashroe.eu>; Neil Horman <nhorman@tuxdriver.com>; dpdk-dev
> > <dev@dpdk.org>; Carrillo, Erik G <erik.g.carrillo@intel.com>; Van Haaren, Harry
> > <harry.van.haaren@intel.com>; Jerin Jacob <jerinj@marvell.com>;
> > david.marchand@redhat.com
> > Subject: Re: [dpdk-dev] [PATCH v2 01/22] event/dlb2: add documentation and
> > meson build infrastructure
> >
> > 20/10/2020 17:17, McDaniel, Timothy:
> > > From: Bruce Richardson <bruce.richardson@intel.com>
> > > > On Sun, Oct 18, 2020 at 02:18:32PM +0530, Jerin Jacob wrote:
> > > > > On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> > > > > <timothy.mcdaniel@intel.com> wrote:
> > > > > >
> > > > > > Adds the meson build infrastructure, which includes
> > > > > > compile-time constants in rte_config.h. DLB2 is
> > > > > > only supported on Linux X86 platforms at this time.
> > > > > >
> > > > > > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > > > > > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > > > > > ---
> > > > > > --- a/drivers/event/meson.build
> > > > > > +++ b/drivers/event/meson.build
> > > > > > @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and
> > > > cc.version().version_compare('<4.8.6') and
> > > > > >         dpdk_conf.has('RTE_ARCH_ARM64'))
> > > > > >         drivers += 'octeontx'
> > > > > >  endif
> > > > > > +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> > > > > > +        drivers += 'dlb2'
> > > > > > +endif
> > > > >
> > > > > Please add the message in "Content Skipped" section,
> > > > > Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> > > > >
> > > >
> > > > The octeontx case is also wrong in this file, IMHO. Rather than checking
> > > > things in the event level and adding things to the list, the list should
> > > > just be static. If something should be optionally compiled, then check the
> > > > conditions in the driver meson.build file itself and add "build=false" to
> > > > disable, setting "reason" to the cause of it being disabled. This keeps all
> > > > the logic about a driver in the other file, rather than someone having to
> > > > look in multiple places for why something is or isn't getting built
> > > > properly.
> > > >
> > > > Regards,
> > > > /Bruce
> > >
> > > Due to time constraints, I would prefer to take these issues up in a future
> > release.
> >
> > If you have strong time constraints to complete everything,
> > then it is better to postpone the feature to the next release.
> >
> 
> You read too much into my comment.
> My point is that there does not seem to be community consensus on this issue,

There is consensus here, and the way the octeon event driver is doing
things is wrong, and was just missed in previous reviews.

> so why are we debating it at this point in the release cycle.  There are plenty of examples
> doing exactly what I am doing.
> 
Looking through the driver/*/meson.build files this appears to be the only
incidence where a driver is optionally adding itself to the list. All other
drivers are always processed so that when enabled/disabled they can be
properly listed in the configuration summary and a reason given.

Regards,
/Bruce
McDaniel, Timothy Oct. 20, 2020, 3:43 p.m. UTC | #10
> -----Original Message-----
> From: Bruce Richardson <bruce.richardson@intel.com>
> Sent: Tuesday, October 20, 2020 10:35 AM
> To: McDaniel, Timothy <timothy.mcdaniel@intel.com>
> Cc: Jerin Jacob <jerinjacobk@gmail.com>; Mcnamara, John
> <john.mcnamara@intel.com>; Kovacevic, Marko
> <marko.kovacevic@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil Horman
> <nhorman@tuxdriver.com>; dpdk-dev <dev@dpdk.org>; Carrillo, Erik G
> <erik.g.carrillo@intel.com>; Eads, Gage <gage.eads@intel.com>; Van Haaren,
> Harry <harry.van.haaren@intel.com>; Jerin Jacob <jerinj@marvell.com>;
> Thomas Monjalon <thomas@monjalon.net>
> Subject: Re: [dpdk-dev] [PATCH v2 01/22] event/dlb2: add documentation and
> meson build infrastructure
> 
> On Tue, Oct 20, 2020 at 04:17:13PM +0100, McDaniel, Timothy wrote:
> >
> >
> > > -----Original Message-----
> > > From: Bruce Richardson <bruce.richardson@intel.com>
> > > Sent: Monday, October 19, 2020 3:34 AM
> > > To: Jerin Jacob <jerinjacobk@gmail.com>
> > > Cc: McDaniel, Timothy <timothy.mcdaniel@intel.com>; Mcnamara, John
> > > <john.mcnamara@intel.com>; Kovacevic, Marko
> > > <Marko.Kovacevic@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil
> Horman
> > > <nhorman@tuxdriver.com>; dpdk-dev <dev@dpdk.org>; Carrillo, Erik G
> > > <Erik.G.Carrillo@intel.com>; Eads, Gage <gage.eads@intel.com>; Van
> Haaren,
> > > Harry <harry.van.haaren@intel.com>; Jerin Jacob <jerinj@marvell.com>;
> > > Thomas Monjalon <thomas@monjalon.net>
> > > Subject: Re: [dpdk-dev] [PATCH v2 01/22] event/dlb2: add documentation
> and
> > > meson build infrastructure
> > >
> > > On Sun, Oct 18, 2020 at 02:18:32PM +0530, Jerin Jacob wrote:
> > > > On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> > > > <timothy.mcdaniel@intel.com> wrote:
> > > > >
> > > > > Adds the meson build infrastructure, which includes
> > > > > compile-time constants in rte_config.h. DLB2 is
> > > > > only supported on Linux X86 platforms at this time.
> > > > >
> > > > > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > > > > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > > > > ---
> > > > >  config/rte_config.h                               |   7 +
> > > > >  doc/guides/eventdevs/dlb2.rst                     | 330
> ++++++++++++++++++++++
> > > > >  doc/guides/eventdevs/index.rst                    |   1 +
> > > > >  drivers/event/dlb2/meson.build                    |   7 +
> > > > >  drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
> > > > >  drivers/event/meson.build                         |   3 +
> > > > >  6 files changed, 351 insertions(+)
> > > > >  create mode 100644 doc/guides/eventdevs/dlb2.rst
> > > > >  create mode 100644 drivers/event/dlb2/meson.build
> > > > >  create mode 100644
> drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> > > > >
> > > > > diff --git a/config/rte_config.h b/config/rte_config.h
> > > > > index 0bae630..fd1b3c3 100644
> > > > > --- a/config/rte_config.h
> > > > > +++ b/config/rte_config.h
> > > > > @@ -131,4 +131,11 @@
> > > > >  /* QEDE PMD defines */
> > > > >  #define RTE_LIBRTE_QEDE_FW ""
> > > > >
> > > > > +/* DLB2 defines */
> > > > > +#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
> > > > > +#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
> > > > > +#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
> > > > > +#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
> > > > > +#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
> > > >
> > > > We are going way with GLOBAL compile time options for drivers.
> > > > I think,  we should move to driver-specific folder not pollute top
> > > > level config file.
> > > > @Richardson, Bruce  @Thomas Monjalon  Thoughts?
> > > >
> > > Yes, we do need a better way to pass driver-specific build config options.
> > > How likely is it that the user may want to tweak these values? If it's not
> > > likely having them just as regular defines in the driver folder may be
> > > better, though they are not particularly problematic in rte_config.h given
> > > the number of other values already there.
> > >
> > > >
> > > > > +
> > > <snip>
> > > > > --- a/drivers/event/meson.build
> > > > > +++ b/drivers/event/meson.build
> > > > > @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and
> > > cc.version().version_compare('<4.8.6') and
> > > > >         dpdk_conf.has('RTE_ARCH_ARM64'))
> > > > >         drivers += 'octeontx'
> > > > >  endif
> > > > > +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> > > > > +        drivers += 'dlb2'
> > > > > +endif
> > > >
> > > > Please add the message in "Content Skipped" section,
> > > > Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> > > >
> > >
> > > The octeontx case is also wrong in this file, IMHO. Rather than checking
> > > things in the event level and adding things to the list, the list should
> > > just be static. If something should be optionally compiled, then check the
> > > conditions in the driver meson.build file itself and add "build=false" to
> > > disable, setting "reason" to the cause of it being disabled. This keeps all
> > > the logic about a driver in the other file, rather than someone having to
> > > look in multiple places for why something is or isn't getting built
> > > properly.
> > >
> > > Regards,
> > > /Bruce
> >
> > Due to time constraints, I would prefer to take these issues up in a future
> release.
> >
> I'm not suggesting you need to fix the existing octeon case, but it's easy
> enough to add dlb2 to the existing list and add :
> 
> if not dpdk_conf.has('RTE_ARCH_X86_64') or not is_linux
> 	build = false
> 	reason = "..."
> endif
> 
> to the dlb2 meson.build file.
> 
> Regards,
> /Bruce

Very well.  I used the existing event/meson.build and conditional inclusion of the octeon driver
as my guide for conditionally including DLB and DLB2.  It's easy enough to change, so I will do it.
McDaniel, Timothy Oct. 21, 2020, 4:33 p.m. UTC | #11
> -----Original Message-----
> From: Bruce Richardson <bruce.richardson@intel.com>
> Sent: Monday, October 19, 2020 3:34 AM
> To: Jerin Jacob <jerinjacobk@gmail.com>
> Cc: McDaniel, Timothy <timothy.mcdaniel@intel.com>; Mcnamara, John
> <john.mcnamara@intel.com>; Kovacevic, Marko
> <Marko.Kovacevic@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil Horman
> <nhorman@tuxdriver.com>; dpdk-dev <dev@dpdk.org>; Carrillo, Erik G
> <Erik.G.Carrillo@intel.com>; Eads, Gage <gage.eads@intel.com>; Van Haaren,
> Harry <harry.van.haaren@intel.com>; Jerin Jacob <jerinj@marvell.com>;
> Thomas Monjalon <thomas@monjalon.net>
> Subject: Re: [dpdk-dev] [PATCH v2 01/22] event/dlb2: add documentation and
> meson build infrastructure
> 
> On Sun, Oct 18, 2020 at 02:18:32PM +0530, Jerin Jacob wrote:
> > On Sat, Oct 17, 2020 at 11:50 PM Timothy McDaniel
> > <timothy.mcdaniel@intel.com> wrote:
> > >
> > > Adds the meson build infrastructure, which includes
> > > compile-time constants in rte_config.h. DLB2 is
> > > only supported on Linux X86 platforms at this time.
> > >
> > > Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
> > > Reviewed-by: Gage Eads <gage.eads@intel.com>
> > > ---
> > >  config/rte_config.h                               |   7 +
> > >  doc/guides/eventdevs/dlb2.rst                     | 330 ++++++++++++++++++++++
> > >  doc/guides/eventdevs/index.rst                    |   1 +
> > >  drivers/event/dlb2/meson.build                    |   7 +
> > >  drivers/event/dlb2/rte_pmd_dlb2_event_version.map |   3 +
> > >  drivers/event/meson.build                         |   3 +
> > >  6 files changed, 351 insertions(+)
> > >  create mode 100644 doc/guides/eventdevs/dlb2.rst
> > >  create mode 100644 drivers/event/dlb2/meson.build
> > >  create mode 100644 drivers/event/dlb2/rte_pmd_dlb2_event_version.map
> > >
> > > diff --git a/config/rte_config.h b/config/rte_config.h
> > > index 0bae630..fd1b3c3 100644
> > > --- a/config/rte_config.h
> > > +++ b/config/rte_config.h
> > > @@ -131,4 +131,11 @@
> > >  /* QEDE PMD defines */
> > >  #define RTE_LIBRTE_QEDE_FW ""
> > >
> > > +/* DLB2 defines */
> > > +#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
> > > +#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
> > > +#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
> > > +#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
> > > +#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
> >
> > We are going way with GLOBAL compile time options for drivers.
> > I think,  we should move to driver-specific folder not pollute top
> > level config file.
> > @Richardson, Bruce  @Thomas Monjalon  Thoughts?
> >
> Yes, we do need a better way to pass driver-specific build config options.
> How likely is it that the user may want to tweak these values? If it's not
> likely having them just as regular defines in the driver folder may be
> better, though they are not particularly problematic in rte_config.h given
> the number of other values already there.
> 

We were careful to only place those options that were likely to be modified by the end user
here.

> >
> > > +
> <snip>
> > > --- a/drivers/event/meson.build
> > > +++ b/drivers/event/meson.build
> > > @@ -10,6 +10,9 @@ if not (toolchain == 'gcc' and
> cc.version().version_compare('<4.8.6') and
> > >         dpdk_conf.has('RTE_ARCH_ARM64'))
> > >         drivers += 'octeontx'
> > >  endif
> > > +if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
> > > +        drivers += 'dlb2'
> > > +endif
> >
> > Please add the message in "Content Skipped" section,
> > Reference: grep "reason" in drivers/vdpa/mlx5/meson.build
> >
> 
> The octeontx case is also wrong in this file, IMHO. Rather than checking
> things in the event level and adding things to the list, the list should
> just be static. If something should be optionally compiled, then check the
> conditions in the driver meson.build file itself and add "build=false" to
> disable, setting "reason" to the cause of it being disabled. This keeps all
> the logic about a driver in the other file, rather than someone having to
> look in multiple places for why something is or isn't getting built
> properly.
> 
> Regards,
> /Bruce

Patch
diff mbox series

diff --git a/config/rte_config.h b/config/rte_config.h
index 0bae630..fd1b3c3 100644
--- a/config/rte_config.h
+++ b/config/rte_config.h
@@ -131,4 +131,11 @@ 
 /* QEDE PMD defines */
 #define RTE_LIBRTE_QEDE_FW ""
 
+/* DLB2 defines */
+#define RTE_LIBRTE_PMD_DLB2_POLL_INTERVAL 1000
+#define RTE_LIBRTE_PMD_DLB2_UMWAIT_CTL_STATE  0
+#undef RTE_LIBRTE_PMD_DLB2_QUELL_STATS
+#define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32
+#define RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
+
 #endif /* _RTE_CONFIG_H_ */
diff --git a/doc/guides/eventdevs/dlb2.rst b/doc/guides/eventdevs/dlb2.rst
new file mode 100644
index 0000000..fa8d6dd
--- /dev/null
+++ b/doc/guides/eventdevs/dlb2.rst
@@ -0,0 +1,330 @@ 
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) 2020 Intel Corporation.
+
+Driver for the Intel® Dynamic Load Balancer (DLB2)
+==================================================
+
+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 DLB2 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 DLB2 provides the functions of a DPDK event device; specifically, it
+supports atomic, ordered, and parallel scheduling events from queues to ports.
+However, the DLB2 hardware is not a perfect match to the eventdev API. Some DLB2
+features are abstracted by the PMD such as directed ports.
+
+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 DLB2 misalign.
+
+Scheduling Domain Configuration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There are 32 scheduling domainis the DLB2.
+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 DLB2 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.
+
+Load-balanced and Directed Ports
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+DLB2 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 DLB2 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 preserved in the event when it is scheduled in the
+DLB2.
+
+Hardware Credits
+~~~~~~~~~~~~~~~~
+
+DLB2 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 DLB2 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 DLB2-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 DLB2 hardware.
+
+Software Credits
+~~~~~~~~~~~~~~~~
+
+The DLB2 is a "closed system" event dev, and the DLB2 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 DLB2'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 DLB2 ought to retry its enqueues if they fail.
+If enqueue fails, DLB2 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 DLB2 supports event priority and per-port queue service priority, as
+described in the eventdev header file. The DLB2 does not support 'global' event
+queue priority established at queue creation time.
+
+DLB2 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
+DLB2 priority, discarding the 5 least significant bits. The 5 least significant
+event priority bits are not preserved when an event is enqueued.
+
+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.  DLB2 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 DLB2 device, it cannot change the
+sequence number configuration.)
+
+The queue's ``nb_atomic_flows`` parameter is ignored by the DLB2 PMD, because
+the DLB2 does not limit the number of flows a queue can track. In the DLB2, all
+load-balanced queues can use the full 16-bit flow ID range.
+
+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 DLB2 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.
+
+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
+
+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
+
diff --git a/doc/guides/eventdevs/index.rst b/doc/guides/eventdevs/index.rst
index bb66a5e..55d5ba8 100644
--- a/doc/guides/eventdevs/index.rst
+++ b/doc/guides/eventdevs/index.rst
@@ -18,3 +18,4 @@  application through the eventdev API.
     octeontx
     octeontx2
     opdl
+    dlb2
diff --git a/drivers/event/dlb2/meson.build b/drivers/event/dlb2/meson.build
new file mode 100644
index 0000000..54ba2c8
--- /dev/null
+++ b/drivers/event/dlb2/meson.build
@@ -0,0 +1,7 @@ 
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2019-2020 Intel Corporation
+
+sources = files(
+)
+
+deps += ['mbuf', 'mempool', 'ring', 'pci', 'bus_pci']
diff --git a/drivers/event/dlb2/rte_pmd_dlb2_event_version.map b/drivers/event/dlb2/rte_pmd_dlb2_event_version.map
new file mode 100644
index 0000000..299ae63
--- /dev/null
+++ b/drivers/event/dlb2/rte_pmd_dlb2_event_version.map
@@ -0,0 +1,3 @@ 
+DPDK_21.0 {
+	local: *;
+};
diff --git a/drivers/event/meson.build b/drivers/event/meson.build
index ebe76a7..01d3b59 100644
--- a/drivers/event/meson.build
+++ b/drivers/event/meson.build
@@ -10,6 +10,9 @@  if not (toolchain == 'gcc' and cc.version().version_compare('<4.8.6') and
 	dpdk_conf.has('RTE_ARCH_ARM64'))
 	drivers += 'octeontx'
 endif
+if (dpdk_conf.has('RTE_ARCH_X86_64') and is_linux)
+        drivers += 'dlb2'
+endif
 std_deps = ['eventdev', 'kvargs']
 config_flag_fmt = 'RTE_LIBRTE_@0@_EVENTDEV_PMD'
 driver_name_fmt = 'rte_pmd_@0@_event'