[dpdk-dev] [PATCH v7 1/5] ethdev: introduce shared Rx queue
Ajit Khaparde
ajit.khaparde at broadcom.com
Sun Oct 17 07:33:15 CEST 2021
On Sat, Oct 16, 2021 at 1:43 AM Xueming Li <xuemingl at nvidia.com> wrote:
>
> In current DPDK framework, each Rx queue is pre-loaded with mbufs to
> save incoming packets. For some PMDs, when number of representors scale
> out in a switch domain, the memory consumption became significant.
> Polling all ports also leads to high cache miss, high latency and low
> throughput.
>
> This patch introduce shared Rx queue. Ports in same Rx domain and
> switch domain could share Rx queue set by specifying non-zero sharing
> group in Rx queue configuration.
>
> Port A RxQ X can share RxQ with Port B RxQ X, but can't share with RxQ
> Y. All member ports in share group share a list of shared Rx queue
> indexed by Rx queue ID.
>
> No special API is defined to receive packets from shared Rx queue.
> Polling any member port of a shared Rx queue receives packets of that
> queue for all member ports, source port is identified by mbuf->port.
Is this port the physical port which received the packet?
Or does this port number correlate with the port_id seen by the application?
>
> Shared Rx queue must be polled in same thread or core, polling a queue
> ID of any member port is essentially same.
So it is upto the application to poll the queue of any member port or
all ports or a designated port to handle Rx?
>
> Multiple share groups are supported. Device should support mixed
> configuration by allowing multiple share groups and non-shared Rx queue.
>
> Example grouping and polling model to reflect service priority:
> Group1, 2 shared Rx queues per port: PF, rep0, rep1
> Group2, 1 shared Rx queue per port: rep2, rep3, ... rep127
> Core0: poll PF queue0
> Core1: poll PF queue1
> Core2: poll rep2 queue0
>
> PMD advertise shared Rx queue capability via RTE_ETH_DEV_CAPA_RXQ_SHARE.
>
> PMD is responsible for shared Rx queue consistency checks to avoid
> member port's configuration contradict to each other.
>
> Signed-off-by: Xueming Li <xuemingl at nvidia.com>
> ---
> doc/guides/nics/features.rst | 13 ++++++++++++
> doc/guides/nics/features/default.ini | 1 +
> .../prog_guide/switch_representation.rst | 10 +++++++++
> doc/guides/rel_notes/release_21_11.rst | 6 ++++++
> lib/ethdev/rte_ethdev.c | 8 +++++++
> lib/ethdev/rte_ethdev.h | 21 +++++++++++++++++++
> 6 files changed, 59 insertions(+)
>
> diff --git a/doc/guides/nics/features.rst b/doc/guides/nics/features.rst
> index e346018e4b8..b64433b8ea5 100644
> --- a/doc/guides/nics/features.rst
> +++ b/doc/guides/nics/features.rst
> @@ -615,6 +615,19 @@ Supports inner packet L4 checksum.
> ``tx_offload_capa,tx_queue_offload_capa:DEV_TX_OFFLOAD_OUTER_UDP_CKSUM``.
>
>
> +.. _nic_features_shared_rx_queue:
> +
> +Shared Rx queue
> +---------------
> +
> +Supports shared Rx queue for ports in same Rx domain of a switch domain.
> +
> +* **[uses] rte_eth_dev_info**: ``dev_capa:RTE_ETH_DEV_CAPA_RXQ_SHARE``.
> +* **[uses] rte_eth_dev_info,rte_eth_switch_info**: ``rx_domain``, ``domain_id``.
> +* **[uses] rte_eth_rxconf**: ``share_group``.
> +* **[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 d473b94091a..93f5d1b46f4 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 ff6aa91c806..de41db8385d 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/networking/switchdev.txt>`_
>
> +- For some PMDs, memory usage of representors is huge when number of
> + representor grows, mbufs are allocated for each descriptor of Rx queue.
> + Polling 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 among same Rx domain. ``RTE_ETH_DEV_CAPA_RXQ_SHARE`` is
> + present in device capability of device info. Setting non-zero share group
> + in Rx queue configuration to enable share. Polling any member port can
> + receive packets of all member ports in the group, port ID is saved in
> + ``mbuf.port``.
> +
> Basic SR-IOV
> ------------
>
> diff --git a/doc/guides/rel_notes/release_21_11.rst b/doc/guides/rel_notes/release_21_11.rst
> index 4c56cdfeaaa..1c84e896554 100644
> --- a/doc/guides/rel_notes/release_21_11.rst
> +++ b/doc/guides/rel_notes/release_21_11.rst
> @@ -67,6 +67,12 @@ New Features
> * Modified to allow ``--huge-dir`` option to specify a sub-directory
> within a hugetlbfs mountpoint.
>
> +* **Added ethdev shared Rx queue support.**
> +
> + * Added new device capability flag and rx domain field to switch info.
> + * Added share group to Rx queue configuration.
> + * Added testpmd support and dedicate forwarding engine.
> +
> * **Added new RSS offload types for IPv4/L4 checksum in RSS flow.**
>
> Added macros ETH_RSS_IPV4_CHKSUM and ETH_RSS_L4_CHKSUM, now IPv4 and
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> index 028907bc4b9..bc55f899f72 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -2159,6 +2159,14 @@ rte_eth_rx_queue_setup(uint16_t port_id, uint16_t rx_queue_id,
> return -EINVAL;
> }
>
> + if (local_conf.share_group > 0 &&
> + (dev_info.dev_capa & RTE_ETH_DEV_CAPA_RXQ_SHARE) == 0) {
> + RTE_ETHDEV_LOG(ERR,
> + "Ethdev port_id=%d rx_queue_id=%d, enabled share_group=%hu while device doesn't support Rx queue share\n",
> + port_id, rx_queue_id, local_conf.share_group);
> + return -EINVAL;
> + }
> +
> /*
> * If LRO is enabled, check that the maximum aggregated packet
> * size is supported by the configured device.
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
> index 6d80514ba7a..59d8904ac7c 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -1044,6 +1044,13 @@ 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. */
> + /**
> + * Share group index in Rx domain and switch domain.
> + * Non-zero value to enable Rx queue share, zero value disable share.
> + * PMD driver is responsible for Rx queue consistency checks to avoid
> + * member port's configuration contradict to each other.
> + */
> + uint16_t share_group;
> /**
> * Per-queue Rx offloads to be set using DEV_RX_OFFLOAD_* flags.
> * Only offloads set on rx_queue_offload_capa or rx_offload_capa
> @@ -1445,6 +1452,14 @@ struct rte_eth_conf {
> #define RTE_ETH_DEV_CAPA_RUNTIME_RX_QUEUE_SETUP 0x00000001
> /** Device supports Tx queue setup after device started. */
> #define RTE_ETH_DEV_CAPA_RUNTIME_TX_QUEUE_SETUP 0x00000002
> +/**
> + * Device supports shared Rx queue among ports within Rx domain and
> + * switch domain. Mbufs are consumed by shared Rx queue instead of
> + * every port. Multiple groups is supported by share_group of Rx
> + * queue configuration. Polling any port in the group receive packets
> + * of all member ports, source port identified by mbuf->port field.
> + */
> +#define RTE_ETH_DEV_CAPA_RXQ_SHARE RTE_BIT64(2)
> /**@}*/
>
> /*
> @@ -1488,6 +1503,12 @@ struct rte_eth_switch_info {
> * but each driver should explicitly define the mapping of switch
> * port identifier to that physical interconnect/switch
> */
> + /**
> + * Shared Rx queue sub-domain boundary. Only ports in same Rx domain
> + * and switch domain can share Rx queue. Valid only if device advertised
> + * RTE_ETH_DEV_CAPA_RXQ_SHARE capability.
> + */
> + uint16_t rx_domain;
> };
>
> /**
> --
> 2.33.0
>
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