[dpdk-dev] [PATCH 1/2] eventdev: add event adapter for ethernet Rx queues

[Nipun Gupta]

> -----Original Message-----
> From: Van Haaren, Harry [mailto:harry.van.haaren at intel.com]
> Sent: Monday, July 24, 2017 16:03
> To: Nipun Gupta <nipun.gupta at nxp.com>; Rao, Nikhil <nikhil.rao at intel.com>;
> jerin.jacob at caviumnetworks.com
> Cc: Eads, Gage <gage.eads at intel.com>; dev at dpdk.org;
> thomas at monjalon.net; Richardson, Bruce <bruce.richardson at intel.com>;
> Hemant Agrawal <hemant.agrawal at nxp.com>; Vangati, Narender
> <narender.vangati at intel.com>; Gujjar, Abhinandan S
> <abhinandan.gujjar at intel.com>
> Subject: RE: [PATCH 1/2] eventdev: add event adapter for ethernet Rx queues
> 
> > From: Nipun Gupta [mailto:nipun.gupta at nxp.com]
> > Sent: Monday, July 24, 2017 11:11 AM
> > To: Rao, Nikhil <nikhil.rao at intel.com>; jerin.jacob at caviumnetworks.com
> > Cc: Eads, Gage <gage.eads at intel.com>; dev at dpdk.org;
> thomas at monjalon.net; Richardson, Bruce
> > <bruce.richardson at intel.com>; Van Haaren, Harry
> <harry.van.haaren at intel.com>; Hemant
> > Agrawal <hemant.agrawal at nxp.com>; Vangati, Narender
> <narender.vangati at intel.com>; Gujjar,
> > Abhinandan S <abhinandan.gujjar at intel.com>
> > Subject: RE: [PATCH 1/2] eventdev: add event adapter for ethernet Rx queues
> >
> > Hi Nikhil/Edas,
> 
> Hi All,
> 
> I'll reply on the service-cores topic, and leave the config to those more involved
> and familiar with them than I :)
> 
> > > -----Original Message-----
> > > From: Nikhil Rao [mailto:nikhil.rao at intel.com]
> > > Sent: Friday, July 07, 2017 3:23
> > > To: jerin.jacob at caviumnetworks.com
> > > Cc: gage.eads at intel.com; dev at dpdk.org; thomas at monjalon.net;
> > > bruce.richardson at intel.com; harry.van.haaren at intel.com; Hemant Agrawal
> > > <hemant.agrawal at nxp.com>; Nipun Gupta <nipun.gupta at nxp.com>;
> > > narender.vangati at intel.com; Nikhil Rao <nikhil.rao at intel.com>;
> Abhinandan
> > > Gujjar <abhinandan.gujjar at intel.com>
> > > Subject: [PATCH 1/2] eventdev: add event adapter for ethernet Rx queues
> > >
> > > Eventdev-based networking applications require a component to dequeue
> > > packets from NIC Rx queues and inject them into eventdev queues[1]. While
> > > some platforms (e.g. Cavium Octeontx) do this operation in hardware, other
> > > platforms use software.
> > >
> > > This patchset introduces an ethernet Rx event adapter that dequeues packets
> > > from ethernet devices and enqueues them to event devices. It is based on
> > > a previous RFC[2].
> > >
> > > The adapter is designed to work with the EAL service core[3]. If
> > > an application determines that the adapter is required, it can register and
> > > launch it on a service core. Alternatively, this adapter can serve as a
> > > template for applications to design customer ethernet Rx event adapters
> > > better suited to their needs.
> > >
> > > The adapter can service multiple ethernet devices and queues. Each queue is
> > > configured with a servicing weight to control the relative frequency with
> > > which the adapter polls the queue, and the event fields to use when
> > > constructing packet events. The adapter has two modes for programming an
> > > event's flow ID: use a static per-queue user-specified value or use the RSS
> > > hash.
> > >
> > > A detailed description of the adapter is contained in the header's
> > > comments.
> > >
> > > [1] http://dpdk.org/ml/archives/dev/2017-May/065341.html
> > > [2] http://dpdk.org/ml/archives/dev/2017-May/065539.html
> > > [3] http://dpdk.org/ml/archives/dev/2017-July/069782.html
> > >
> > > Signed-off-by: Nikhil Rao <nikhil.rao at intel.com>
> > > Signed-off-by: Gage Eads <gage.eads at intel.com>
> > > Signed-off-by: Abhinandan Gujjar <abhinandan.gujjar at intel.com>
> > > ---
> > >
> > > v2:
> > > Thanks Jerin for review - below is a list of changes you
> > > suggested.
> > >
> > > - all public symbols are started with rte_event_.
> > > - Add Doxygen reference with @see.
> > > - Mention setting of ev.event_type.
> > > - Mention adapter to service function mapping.
> > > - Remove rte_eth_rx_event_adapter_dev_add/del().
> > > - Change rx_queuee_id to int32_t and use -1 to denote all Rx queues.
> > > - Add rte_eth_event_rx_queue_del().
> > >
> > > Other changes
> > > - Remove adapter's run function (rte_event_eth_rx_adapter_run()) from
> > >   the public interface. The adapter internally uses it to create a
> > >   service.
> > > - Add a blocked cycle count to stats. Further description is contained
> > >   in the header.
> > > - Minor struct renames rte_event_eth_rx_adapter_config -> .._conf
> > > ---
> > >  lib/librte_eventdev/rte_event_eth_rx_adapter.h | 301 +++++++++
> > >  lib/librte_eventdev/rte_event_eth_rx_adapter.c | 825
> > > +++++++++++++++++++++++++
> > >  lib/librte_eventdev/rte_eventdev_version.map   |  13 +
> > >  lib/Makefile                                   |   2 +-
> > >  lib/librte_eventdev/Makefile                   |   2 +
> > >  5 files changed, 1142 insertions(+), 1 deletion(-)
> > >  create mode 100644 lib/librte_eventdev/rte_event_eth_rx_adapter.h
> > >  create mode 100644 lib/librte_eventdev/rte_event_eth_rx_adapter.c
> > >
> > > diff --git a/lib/librte_eventdev/rte_event_eth_rx_adapter.h
> > > b/lib/librte_eventdev/rte_event_eth_rx_adapter.h
> > > new file mode 100644
> > > index 000000000..5ccd0bd24
> > > --- /dev/null
> > > +++ b/lib/librte_eventdev/rte_event_eth_rx_adapter.h
> > > @@ -0,0 +1,301 @@
> > > +/*
> > > + *   Copyright(c) 2017 Intel Corporation. All rights reserved.
> > > + *   All rights reserved.
> > > + *
> > > + *   Redistribution and use in source and binary forms, with or without
> > > + *   modification, are permitted provided that the following conditions
> > > + *   are met:
> > > + *
> > > + *     * Redistributions of source code must retain the above copyright
> > > + *       notice, this list of conditions and the following disclaimer.
> > > + *     * Redistributions in binary form must reproduce the above copyright
> > > + *       notice, this list of conditions and the following disclaimer in
> > > + *       the documentation and/or other materials provided with the
> > > + *       distribution.
> > > + *     * Neither the name of Intel Corporation nor the names of its
> > > + *       contributors may be used to endorse or promote products derived
> > > + *       from this software without specific prior written permission.
> > > + *
> > > + *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
> > > CONTRIBUTORS
> > > + *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
> NOT
> > > + *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
> > > FITNESS FOR
> > > + *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
> > > COPYRIGHT
> > > + *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
> > > INCIDENTAL,
> > > + *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
> BUT
> > > NOT
> > > + *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
> LOSS
> > > OF USE,
> > > + *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
> AND
> > > ON ANY
> > > + *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> > > TORT
> > > + *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
> OF
> > > THE USE
> > > + *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
> > > DAMAGE.
> > > + */
> > > +
> > > +#ifndef _RTE_EVENT_ETH_RX_ADAPTER_
> > > +#define _RTE_EVENT_ETH_RX_ADAPTER_
> > > +
> > > +/**
> > > + * @file
> > > + *
> > > + * RTE Event Ethernet Rx Adapter
> > > + *
> > > + * An eventdev-based packet processing application enqueues/dequeues
> mbufs
> > > + * to/from the event device. The ethernet Rx event adapter's role is to
> transfer
> > > + * mbufs from the ethernet receive queues managed by DPDK to an event
> > > device.
> > > + * The application uses the adapter APIs to configure the packet flow
> between
> > > + * the ethernet devices and event devices. The adapter is designed to work
> with
> > > + * the EAL service cores. The adapter's work can be parallelized by dividing
> the
> > > + * NIC Rx queues among multiple adapter services that run in parallel.
> >
> > First of all, apologies for commenting late on this. I am going through this
> patchset and
> > have some concerns over this.
> > It is mentioned that "The adapter is designed to work with * the EAL service
> cores"
> > Does this mean that the adapter cannot function without service core?
> > In the case where Ethdev HW is capable of injecting the packet to compatible
> HW eventdev
> > driver, there is no service
> > required. It seems this patchset does not take care of this use-case or maybe I
> am missing
> > something here?
> 
> 
> The "service cores" is a method of abstracting lcore requirements. In short, with
> a SW PMD, a service core is required to perform the event scheduling. With the
> HW use case as you describe, no core is required. So in the HW case, no service
> cores are allocated in DPDK, and as a result, all your cores are available to the
> application.
> 
> If I understand correctly, the generic "Event Ethernet RX Adapter" will register a
> service which needs to be run (by a service core) in order to perform SW polling
> of the NIC, and enqueue to the eventdev.
> 
> In order to support the hardware use-case, no service is registered and no
> service lcores required. The HW is allowed to perform the Ethdev -> Eventdev
> enqueue.
> 
> Hope that makes sense! -Harry

With function pointer based approach the adapter calls will be propagated to eventdev PMD so
here won't this way the event driver will be responsible for registering the service? I don't think the
generic 'Event ethernet Rx adapter' would register a service with this model.

Thanks,
Nipun