> > > > > > > > > > > > > > In current DPDK framework, each RX queue is
> > > > > > > > > > > > > > pre-loaded with mbufs
> > > > > > > > > > > > > > for incoming packets. When number of
> > > > > > > > > > > > > > representors scale out in a
> > > > > > > > > > > > > > switch domain, the memory consumption became
> > > > > > > > > > > > > > significant. Most
> > > > > > > > > > > > > > important, polling all ports leads to high
> > > > > > > > > > > > > > cache miss, high
> > > > > > > > > > > > > > latency and low throughput.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > This patch introduces shared RX queue. Ports
> > > > > > > > > > > > > > with same
> > > > > > > > > > > > > > configuration in a switch domain could share
> > > > > > > > > > > > > > RX queue set by specifying sharing group.
> > > > > > > > > > > > > > Polling any queue using same shared RX queue
> > > > > > > > > > > > > > receives packets from
> > > > > > > > > > > > > > all member ports. Source port is identified
> > > > > > > > > > > > > > by mbuf->port.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Port queue number in a shared group should be
> > > > > > > > > > > > > > identical. Queue
> > > > > > > > > > > > > > index is
> > > > > > > > > > > > > > 1:1 mapped in shared group.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Share RX queue is supposed to be polled on
> > > > > > > > > > > > > > same thread.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Multiple groups is supported by group ID.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Is this offload specific to the representor? If
> > > > > > > > > > > > > so can this name be changed specifically to
> > > > > > > > > > > > > representor?
> > > > > > > > > > > >
> > > > > > > > > > > > Yes, PF and representor in switch domain could
> > > > > > > > > > > > take advantage.
> > > > > > > > > > > >
> > > > > > > > > > > > > If it is for a generic case, how the flow
> > > > > > > > > > > > > ordering will be maintained?
> > > > > > > > > > > >
> > > > > > > > > > > > Not quite sure that I understood your question.
> > > > > > > > > > > > The control path of is
> > > > > > > > > > > > almost same as before, PF and representor port
> > > > > > > > > > > > still needed, rte flows not impacted.
> > > > > > > > > > > > Queues still needed for each member port,
> > > > > > > > > > > > descriptors(mbuf) will be
> > > > > > > > > > > > supplied from shared Rx queue in my PMD
> > > > > > > > > > > > implementation.
> > > > > > > > > > >
> > > > > > > > > > > My question was if create a generic
> > > > > > > > > > > RTE_ETH_RX_OFFLOAD_SHARED_RXQ offload, multiple
> > > > > > > > > > > ethdev receive queues land into
> > > the same
> > > > > > > > > > > receive queue, In that case, how the flow order is
> > > > > > > > > > > maintained for respective receive queues.
> > > > > > > > > >
> > > > > > > > > > I guess the question is testpmd forward stream? The
> > > > > > > > > > forwarding logic has to be changed slightly in case
> > > > > > > > > > of shared rxq.
> > > > > > > > > > basically for each packet in rx_burst result, lookup
> > > > > > > > > > source stream according to mbuf->port, forwarding to
> > > > > > > > > > target fs.
> > > > > > > > > > Packets from same source port could be grouped as a
> > > > > > > > > > small burst to process, this will accelerates the
> > > > > > > > > > performance if traffic
> > > come from
> > > > > > > > > > limited ports. I'll introduce some common api to do
> > > > > > > > > > shard rxq forwarding, call it with packets handling
> > > > > > > > > > callback, so it suites for
> > > > > > > > > > all forwarding engine. Will sent patches soon.
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > All ports will put the packets in to the same queue
> > > > > > > > > (share queue), right? Does
> > > > > > > > > this means only single core will poll only, what will
> > > > > > > > > happen if there are
> > > > > > > > > multiple cores polling, won't it cause problem?
> > > > > > > > >
> > > > > > > > > And if this requires specific changes in the
> > > > > > > > > application, I am not sure about
> > > > > > > > > the solution, can't this work in a transparent way to
> > > > > > > > > the application?
> > > > > > > >
> > > > > > > > Discussed with Jerin, new API introduced in v3 2/8 that
> > > > > > > > aggregate ports
> > > > > > > > in same group into one new port. Users could schedule
> > > > > > > > polling on the
> > > > > > > > aggregated port instead of all member ports.
> > > > > > >
> > > > > > > The v3 still has testpmd changes in fastpath. Right? IMO,
> > > > > > > For this
> > > > > > > feature, we should not change fastpath of testpmd
> > > > > > > application. Instead, testpmd can use aggregated ports
> > > > > > > probably as
> > > > > > > separate fwd_engine to show how to use this feature.
> > > > > >
> > > > > > Good point to discuss :) There are two strategies to polling
> > > > > > a shared
> > > > > > Rxq:
> > > > > > 1. polling each member port
> > > > > > All forwarding engines can be reused to work as before.
> > > > > > My testpmd patches are efforts towards this direction.
> > > > > > Does your PMD support this?
> > > > >
> > > > > Not unfortunately. More than that, every application needs to
> > > > > change
> > > > > to support this model.
> > > >
> > > > Both strategies need user application to resolve port ID from
> > > > mbuf and
> > > > process accordingly.
> > > > This one doesn't demand aggregated port, no polling schedule
> > > > change.
> > >
> > > I was thinking, mbuf will be updated from driver/aggregator port as
> > > when it
> > > comes to application.
> > >
> > > >
> > > > >
> > > > > > 2. polling aggregated port
> > > > > > Besides forwarding engine, need more work to to demo it.
> > > > > > This is an optional API, not supported by my PMD yet.
> > > > >
> > > > > We are thinking of implementing this PMD when it comes to it,
> > > > > ie.
> > > > > without application change in fastpath
> > > > > logic.
> > > >
> > > > Fastpath have to resolve port ID anyway and forwarding according
> > > > to
> > > > logic. Forwarding engine need to adapt to support shard Rxq.
> > > > Fortunately, in testpmd, this can be done with an abstract API.
> > > >
> > > > Let's defer part 2 until some PMD really support it and tested,
> > > > how do
> > > > you think?
> > >
> > > We are not planning to use this feature so either way it is OK to
> > > me.
> > > I leave to ethdev maintainers decide between 1 vs 2.
> > >
> > > I do have a strong opinion not changing the testpmd basic forward
> > > engines
> > > for this feature.I would like to keep it simple as fastpath
> > > optimized and would
> > > like to add a separate Forwarding engine as means to verify this
> > > feature.
> >
> > +1 to that.
> > I don't think it a 'common' feature.
> > So separate FWD mode seems like a best choice to me.
>
> -1 :)
> There was some internal requirement from test team, they need to verify
> all features like packet content, rss, vlan, checksum, rte_flow... to
> be working based on shared rx queue.
Then I suppose you'll need to write really comprehensive fwd-engine
to satisfy your test team :)
Speaking seriously, I still don't understand why do you need all
available fwd-engines to verify this feature.
From what I understand, main purpose of your changes to test-pmd:
allow to fwd packet though different fwd_stream (TX through different HW queue).
In theory, if implemented in generic and extendable way - that
might be a useful add-on to tespmd fwd functionality.
But current implementation looks very case specific.
And as I don't think it is a common case, I don't see much point to pollute
basic fwd cases with it.
BTW, as a side note, the code below looks bogus to me:
+void
+forward_shared_rxq(struct fwd_stream *fs, uint16_t nb_rx,
+ struct rte_mbuf **pkts_burst, packet_fwd_cb fwd)
+{
+ uint16_t i, nb_fs_rx = 1, port;
+
+ /* Locate real source fs according to mbuf->port. */
+ for (i = 0; i < nb_rx; ++i) {
+ rte_prefetch0(pkts_burst[i + 1]);
you access pkt_burst[] beyond array boundaries,
also you ask cpu to prefetch some unknown and possibly invalid address.
> Based on the patch, I believe the
> impact has been minimized.
>
> >
> > >
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > > >
> > > > > > > >
> > > > > > > > >
> > > > > > > > > Overall, is this for optimizing memory for the port
> > > > > > > > > represontors? If so can't we
> > > > > > > > > have a port representor specific solution, reducing
> > > > > > > > > scope can reduce the
> > > > > > > > > complexity it brings?
> > > > > > > > >
> > > > > > > > > > > If this offload is only useful for representor
> > > > > > > > > > > case, Can we make this offload specific to
> > > > > > > > > > > representor the case by changing its
> > > name and
> > > > > > > > > > > scope.
> > > > > > > > > >
> > > > > > > > > > It works for both PF and representors in same switch
> > > > > > > > > > domain, for application like OVS, few changes to
> > > > > > > > > > apply.
> > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Signed-off-by: Xueming Li
> > > > > > > > > > > > > > <xuemi...@nvidia.com>
> > > > > > > > > > > > > > ---
> > > > > > > > > > > > > > doc/guides/nics/features.rst
> > > > > > > > > > > > > > | 11 +++++++++++
> > > > > > > > > > > > > > doc/guides/nics/features/default.ini
> > > > > > > > > > > > > > | 1 +
> > > > > > > > > > > > > > doc/guides/prog_guide/switch_representation.
> > > > > > > > > > > > > > rst | 10 ++++++++++
> > > > > > > > > > > > > > lib/ethdev/rte_ethdev.c
> > > > > > > > > > > > > > | 1 +
> > > > > > > > > > > > > > lib/ethdev/rte_ethdev.h
> > > > > > > > > > > > > > | 7 +++++++
> > > > > > > > > > > > > > 5 files changed, 30 insertions(+)
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > diff --git a/doc/guides/nics/features.rst
> > > > > > > > > > > > > > b/doc/guides/nics/features.rst index
> > > > > > > > > > > > > > a96e12d155..2e2a9b1554 100644
> > > > > > > > > > > > > > --- a/doc/guides/nics/features.rst
> > > > > > > > > > > > > > +++ b/doc/guides/nics/features.rst
> > > > > > > > > > > > > > @@ -624,6 +624,17 @@ Supports inner packet L4
> > > > > > > > > > > > > > checksum.
> > > > > > > > > > > > > > ``tx_offload_capa,tx_queue_offload_capa:DE
> > > > > > > > > > > > > > V_TX_OFFLOAD_OUTER_UDP_CKSUM``.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > +.. _nic_features_shared_rx_queue:
> > > > > > > > > > > > > > +
> > > > > > > > > > > > > > +Shared Rx queue
> > > > > > > > > > > > > > +---------------
> > > > > > > > > > > > > > +
> > > > > > > > > > > > > > +Supports shared Rx queue for ports in same
> > > > > > > > > > > > > > switch domain.
> > > > > > > > > > > > > > +
> > > > > > > > > > > > > > +* **[uses]
> > > > > > > > > > > > > > rte_eth_rxconf,rte_eth_rxmode**:
> > > > > > > > > > > > > > ``offloads:RTE_ETH_RX_OFFLOAD_SHARED_RXQ``.
> > > > > > > > > > > > > > +* **[provides] mbuf**: ``mbuf.port``.
> > > > > > > > > > > > > > +
> > > > > > > > > > > > > > +
> > > > > > > > > > > > > > .. _nic_features_packet_type_parsing:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Packet type parsing
> > > > > > > > > > > > > > diff --git
> > > > > > > > > > > > > > a/doc/guides/nics/features/default.ini
> > > > > > > > > > > > > > b/doc/guides/nics/features/default.ini
> > > > > > > > > > > > > > index 754184ddd4..ebeb4c1851 100644
> > > > > > > > > > > > > > --- a/doc/guides/nics/features/default.ini
> > > > > > > > > > > > > > +++ b/doc/guides/nics/features/default.ini
> > > > > > > > > > > > > > @@ -19,6 +19,7 @@ Free Tx mbuf on demand =
> > > > > > > > > > > > > > Queue start/stop =
> > > > > > > > > > > > > > Runtime Rx queue setup =
> > > > > > > > > > > > > > Runtime Tx queue setup =
> > > > > > > > > > > > > > +Shared Rx queue =
> > > > > > > > > > > > > > Burst mode info =
> > > > > > > > > > > > > > Power mgmt address monitor =
> > > > > > > > > > > > > > MTU update =
> > > > > > > > > > > > > > diff --git
> > > > > > > > > > > > > > a/doc/guides/prog_guide/switch_representation
> > > > > > > > > > > > > > .rst
> > > > > > > > > > > > > > b/doc/guides/prog_guide/switch_representation
> > > > > > > > > > > > > > .rst
> > > > > > > > > > > > > > index ff6aa91c80..45bf5a3a10 100644
> > > > > > > > > > > > > > ---
> > > > > > > > > > > > > > a/doc/guides/prog_guide/switch_representation
> > > > > > > > > > > > > > .rst
> > > > > > > > > > > > > > +++
> > > > > > > > > > > > > > b/doc/guides/prog_guide/switch_representation
> > > > > > > > > > > > > > .rst
> > > > > > > > > > > > > > @@ -123,6 +123,16 @@ thought as a software
> > > > > > > > > > > > > > "patch panel" front-end for applications.
> > > > > > > > > > > > > > .. [1] `Ethernet switch device driver model
> > > > > > > > > > > > > > (switchdev)
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > <https://www.kernel.org/doc/Documentation/net
> > > > > > > > > > > > > > working/switchdev.txt
> > > > > > > > > > > > > > > `_
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > +- Memory usage of representors is huge when
> > > > > > > > > > > > > > number of representor
> > > > > > > > > > > > > > +grows,
> > > > > > > > > > > > > > + because PMD always allocate mbuf for each
> > > > > > > > > > > > > > descriptor of Rx queue.
> > > > > > > > > > > > > > + Polling the large number of ports brings
> > > > > > > > > > > > > > more CPU load, cache
> > > > > > > > > > > > > > +miss and
> > > > > > > > > > > > > > + latency. Shared Rx queue can be used to
> > > > > > > > > > > > > > share Rx queue between
> > > > > > > > > > > > > > +PF and
> > > > > > > > > > > > > > + representors in same switch domain.
> > > > > > > > > > > > > > +``RTE_ETH_RX_OFFLOAD_SHARED_RXQ``
> > > > > > > > > > > > > > + is present in Rx offloading capability of
> > > > > > > > > > > > > > device info. Setting
> > > > > > > > > > > > > > +the
> > > > > > > > > > > > > > + offloading flag in device Rx mode or Rx
> > > > > > > > > > > > > > queue configuration to
> > > > > > > > > > > > > > +enable
> > > > > > > > > > > > > > + shared Rx queue. Polling any member port
> > > > > > > > > > > > > > of shared Rx queue can
> > > > > > > > > > > > > > +return
> > > > > > > > > > > > > > + packets of all ports in group, port ID is
> > > > > > > > > > > > > > saved in ``mbuf.port``.
> > > > > > > > > > > > > > +
> > > > > > > > > > > > > > Basic SR-IOV
> > > > > > > > > > > > > > ------------
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > diff --git a/lib/ethdev/rte_ethdev.c
> > > > > > > > > > > > > > b/lib/ethdev/rte_ethdev.c
> > > > > > > > > > > > > > index 9d95cd11e1..1361ff759a 100644
> > > > > > > > > > > > > > --- a/lib/ethdev/rte_ethdev.c
> > > > > > > > > > > > > > +++ b/lib/ethdev/rte_ethdev.c
> > > > > > > > > > > > > > @@ -127,6 +127,7 @@ static const struct {
> > > > > > > > > > > > > > RTE_RX_OFFLOAD_BIT2STR(OUTER_UDP_CKSU
> > > > > > > > > > > > > > M),
> > > > > > > > > > > > > > RTE_RX_OFFLOAD_BIT2STR(RSS_HASH),
> > > > > > > > > > > > > > RTE_ETH_RX_OFFLOAD_BIT2STR(BUFFER_SPL
> > > > > > > > > > > > > > IT),
> > > > > > > > > > > > > > +
> > > > > > > > > > > > > > RTE_ETH_RX_OFFLOAD_BIT2STR(SHARED_RXQ),
> > > > > > > > > > > > > > };
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > #undef RTE_RX_OFFLOAD_BIT2STR
> > > > > > > > > > > > > > diff --git a/lib/ethdev/rte_ethdev.h
> > > > > > > > > > > > > > b/lib/ethdev/rte_ethdev.h
> > > > > > > > > > > > > > index d2b27c351f..a578c9db9d 100644
> > > > > > > > > > > > > > --- a/lib/ethdev/rte_ethdev.h
> > > > > > > > > > > > > > +++ b/lib/ethdev/rte_ethdev.h
> > > > > > > > > > > > > > @@ -1047,6 +1047,7 @@ struct rte_eth_rxconf {
> > > > > > > > > > > > > > uint8_t rx_drop_en; /**< Drop packets
> > > > > > > > > > > > > > if no descriptors are available. */
> > > > > > > > > > > > > > uint8_t rx_deferred_start; /**< Do
> > > > > > > > > > > > > > not start queue with rte_eth_dev_start(). */
> > > > > > > > > > > > > > uint16_t rx_nseg; /**< Number of
> > > > > > > > > > > > > > descriptions in rx_seg array.
> > > > > > > > > > > > > > */
> > > > > > > > > > > > > > + uint32_t shared_group; /**< Shared
> > > > > > > > > > > > > > port group index in
> > > > > > > > > > > > > > + switch domain. */
> > > > > > > > > > > > > > /**
> > > > > > > > > > > > > > * Per-queue Rx offloads to be set
> > > > > > > > > > > > > > using DEV_RX_OFFLOAD_* flags.
> > > > > > > > > > > > > > * Only offloads set on
> > > > > > > > > > > > > > rx_queue_offload_capa or
> > > > > > > > > > > > > > rx_offload_capa @@ -1373,6 +1374,12 @@ struct
> > > > > > > > > > > > > > rte_eth_conf {
> > > > > > > > > > > > > > #define DEV_RX_OFFLOAD_OUTER_UDP_CKSUM
> > > > > > > > > > > > > > 0x00040000
> > > > > > > > > > > > > > #define DEV_RX_OFFLOAD_RSS_HASH
> > > > > > > > > > > > > > 0x00080000
> > > > > > > > > > > > > > #define RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT
> > > > > > > > > > > > > > 0x00100000
> > > > > > > > > > > > > > +/**
> > > > > > > > > > > > > > + * Rx queue is shared among ports in same
> > > > > > > > > > > > > > switch domain to save
> > > > > > > > > > > > > > +memory,
> > > > > > > > > > > > > > + * avoid polling each port. Any port in
> > > > > > > > > > > > > > group can be used to receive packets.
> > > > > > > > > > > > > > + * Real source port number saved in mbuf-
> > > > > > > > > > > > > > >port field.
> > > > > > > > > > > > > > + */
> > > > > > > > > > > > > > +#define RTE_ETH_RX_OFFLOAD_SHARED_RXQ
> > > > > > > > > > > > > > 0x00200000
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > #define DEV_RX_OFFLOAD_CHECKSUM
> > > > > > > > > > > > > > (DEV_RX_OFFLOAD_IPV4_CKSUM | \
> > > > > > > > > > > > > > DEV_RX_OFFLO
> > > > > > > > > > > > > > AD_UDP_CKSUM | \
> > > > > > > > > > > > > > --
> > > > > > > > > > > > > > 2.25.1
> > > > > > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > >
> > > > > >
> > > >
