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* [dpdk-dev] [RFC] ethdev: introduce Rx buffer split
@ 2020-08-17 17:49 Slava Ovsiienko
  2020-09-17 16:55 ` Andrew Rybchenko
                   ` (13 more replies)
  0 siblings, 14 replies; 172+ messages in thread
From: Slava Ovsiienko @ 2020-08-17 17:49 UTC (permalink / raw)
  To: dev
  Cc: Thomas Monjalon, stephen, ferruh.yigit, Shahaf Shuler,
	olivier.matz, jerinjacobk, maxime.coquelin, david.marchand,
	arybchenko, Asaf Penso

From 7f7052d8b85ff3ff7011bd844b6d3169c6e51923 Mon Sep 17 00:00:00 2001
From: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
Date: Mon, 17 Aug 2020 16:57:43 +0000
Subject: [RFC] ethdev: introduce Rx buffer split

The DPDK datapath in the transmit direction is very flexible.
An application can build the multisegment packet and manages
almost all data aspects - the memory pools where segments
are allocated from, the segment lengths, the memory attributes
like external buffers, registered for DMA, etc.

In the receiving direction, the datapath is much less flexible,
an application can only specify the memory pool to configure the
receiving queue and nothing more. In order to extend receiving
datapath capabilities it is proposed to add the way to provide
extended infoirmation how to split the packets being received.

The following structure is introduced to specify the Rx packet
segment:

struct rte_eth_rxseg {
    struct rte_mempool *mp; /* memory pools to allocate segment from */
    uint16_t length; /* segment maximal data length */
    uint16_t offset; /* data offset from beginning of mbuf data buffer */
    uint32_t reserved; /* reserved field */
};

The new routine rte_eth_rx_queue_setup_ex() is introduced to
setup the given Rx queue using the new extended Rx packet segment
description:

int
rte_eth_rx_queue_setup_ex(uint16_t port_id, uint16_t rx_queue_id,
                          uint16_t nb_rx_desc, unsigned int socket_id,
                          const struct rte_eth_rxconf *rx_conf,
		          const struct rte_eth_rxseg *rx_seg,
                          uint16_t n_seg)

This routine presents the two new parameters:
    rx_seg - pointer the array of segment descriptions, each element
             describes the memory pool, maximal data length, initial
             data offset from the beginning of data buffer in mbuf
    n_seg - number of elements in the array

The new offload flag DEV_RX_OFFLOAD_BUFFER_SPLIT in device
capabilities is introduced to present the way for PMD to report to
application about supporting Rx packet split to configurable
segments. Prior invoking the rte_eth_rx_queue_setup_ex() routine
application should check DEV_RX_OFFLOAD_BUFFER_SPLIT flag.

If the Rx queue is configured with new routine the packets being
received will be split into multiple segments pushed to the mbufs
with specified attributes. The PMD will allocate the first mbuf
from the pool specified in the first segment descriptor and puts
the data staring at specified offeset in the allocated mbuf data
buffer. If packet length exceeds the specified segment length
the next mbuf will be allocated according to the next segment
descriptor (if any) and data will be put in its data buffer at
specified offset and not exceeding specified length. If there is
no next descriptor the next mbuf will be allocated and filled in the
same way (from the same pool and with the same buffer offset/length)
as the current one.

For example, let's suppose we configured the Rx queue with the
following segments:
    seg0 - pool0, len0=14B, off0=RTE_PKTMBUF_HEADROOM
    seg1 - pool1, len1=20B, off1=0B
    seg2 - pool2, len2=20B, off2=0B
    seg3 - pool3, len3=512B, off3=0B

The packet 46 bytes long will look like the following:
    seg0 - 14B long @ RTE_PKTMBUF_HEADROOM in mbuf from pool0
    seg1 - 20B long @ 0 in mbuf from pool1
    seg2 - 12B long @ 0 in mbuf from pool2

The packet 1500 bytes long will look like the following:
    seg0 - 14B @ RTE_PKTMBUF_HEADROOM in mbuf from pool0
    seg1 - 20B @ 0 in mbuf from pool1
    seg2 - 20B @ 0 in mbuf from pool2
    seg3 - 512B @ 0 in mbuf from pool3
    seg4 - 512B @ 0 in mbuf from pool3
    seg5 - 422B @ 0 in mbuf from pool3

The offload DEV_RX_OFFLOAD_SCATTER must be present and
configured to support new buffer spllit feature (if n_seg
is greater than one).

The new approach would allow splitting the ingress packets into
multiple parts pushed to the memory with different attributes.
For example, the packet headers can be pushed to the embedded
data buffers within mbufs and the application data into
the external buffers attached to mbufs allocated from the
different memory pools. The memory attributes for the split
parts may differ either - for example the application data
may be pushed into the external memory located on the dedicated
physical device, say GPU or NVMe. This would improve the DPDK
receiving datapath flexibility with preserving compatibility
with existing API.

Also, the proposed segment description might be used to specify
Rx packet split for some other features. For example, provide
the way to specify the extra memory pool for the Header Split
feature of some Intel PMD.

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 lib/librte_ethdev/rte_ethdev.c      | 166 ++++++++++++++++++++++++++++++++++++
 lib/librte_ethdev/rte_ethdev.h      |  15 ++++
 lib/librte_ethdev/rte_ethdev_core.h |  10 +++
 3 files changed, 191 insertions(+)

diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index 7858ad5..638e42d 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -1933,6 +1933,172 @@ struct rte_eth_dev *
 }
 
 int
+rte_eth_rx_queue_setup_ex(uint16_t port_id, uint16_t rx_queue_id,
+			  uint16_t nb_rx_desc, unsigned int socket_id,
+			  const struct rte_eth_rxconf *rx_conf,
+			  const struct rte_eth_rxseg *rx_seg, uint16_t n_seg)
+{
+	int ret;
+	uint16_t seg_idx;
+	uint32_t mbp_buf_size;
+	struct rte_eth_dev *dev;
+	struct rte_eth_dev_info dev_info;
+	struct rte_eth_rxconf local_conf;
+	void **rxq;
+
+	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -EINVAL);
+
+	dev = &rte_eth_devices[port_id];
+	if (rx_queue_id >= dev->data->nb_rx_queues) {
+		RTE_ETHDEV_LOG(ERR, "Invalid RX queue_id=%u\n", rx_queue_id);
+		return -EINVAL;
+	}
+
+	if (rx_seg == NULL) {
+		RTE_ETHDEV_LOG(ERR, "Invalid null description pointer\n");
+		return -EINVAL;
+	}
+
+	if (n_seg == 0) {
+		RTE_ETHDEV_LOG(ERR, "Invalid zero description number\n");
+		return -EINVAL;
+	}
+
+	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_setup_ex, -ENOTSUP);
+
+	/*
+	 * Check the size of the mbuf data buffer.
+	 * This value must be provided in the private data of the memory pool.
+	 * First check that the memory pool has a valid private data.
+	 */
+	ret = rte_eth_dev_info_get(port_id, &dev_info);
+	if (ret != 0)
+		return ret;
+
+	for (seg_idx = 0; seg_idx < n_seg; seg_idx++) {
+		struct rte_mempool *mp = rx_seg[seg_idx].mp;
+
+		if (mp->private_data_size < sizeof(struct rte_pktmbuf_pool_private)) {
+			RTE_ETHDEV_LOG(ERR, "%s private_data_size %d < %d\n",
+				mp->name, (int)mp->private_data_size,
+				(int)sizeof(struct rte_pktmbuf_pool_private));
+			return -ENOSPC;
+		}
+
+		mbp_buf_size = rte_pktmbuf_data_room_size(mp);
+		if (mbp_buf_size < rx_seg[seg_idx].length + rx_seg[seg_idx].offset) {
+			RTE_ETHDEV_LOG(ERR,
+				"%s mbuf_data_room_size %d < %d"
+				" (segment length=%d + segment offset=%d)\n",
+				mp->name, (int)mbp_buf_size,
+				(int)(rx_seg[seg_idx].length + rx_seg[seg_idx].offset),
+				(int)rx_seg[seg_idx].length,
+				(int)rx_seg[seg_idx].offset);
+			return -EINVAL;
+		}
+	}
+
+	/* Use default specified by driver, if nb_rx_desc is zero */
+	if (nb_rx_desc == 0) {
+		nb_rx_desc = dev_info.default_rxportconf.ring_size;
+		/* If driver default is also zero, fall back on EAL default */
+		if (nb_rx_desc == 0)
+			nb_rx_desc = RTE_ETH_DEV_FALLBACK_RX_RINGSIZE;
+	}
+
+	if (nb_rx_desc > dev_info.rx_desc_lim.nb_max ||
+			nb_rx_desc < dev_info.rx_desc_lim.nb_min ||
+			nb_rx_desc % dev_info.rx_desc_lim.nb_align != 0) {
+
+		RTE_ETHDEV_LOG(ERR,
+			"Invalid value for nb_rx_desc(=%hu), should be: <= %hu, >= %hu, and a product of %hu\n",
+			nb_rx_desc, dev_info.rx_desc_lim.nb_max,
+			dev_info.rx_desc_lim.nb_min,
+			dev_info.rx_desc_lim.nb_align);
+		return -EINVAL;
+	}
+
+	if (dev->data->dev_started &&
+		!(dev_info.dev_capa &
+			RTE_ETH_DEV_CAPA_RUNTIME_RX_QUEUE_SETUP))
+		return -EBUSY;
+
+	if (dev->data->dev_started &&
+		(dev->data->rx_queue_state[rx_queue_id] !=
+			RTE_ETH_QUEUE_STATE_STOPPED))
+		return -EBUSY;
+
+	rxq = dev->data->rx_queues;
+	if (rxq[rx_queue_id]) {
+		RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_release,
+					-ENOTSUP);
+		(*dev->dev_ops->rx_queue_release)(rxq[rx_queue_id]);
+		rxq[rx_queue_id] = NULL;
+	}
+
+	if (rx_conf == NULL)
+		rx_conf = &dev_info.default_rxconf;
+
+	local_conf = *rx_conf;
+
+	/*
+	 * If an offloading has already been enabled in
+	 * rte_eth_dev_configure(), it has been enabled on all queues,
+	 * so there is no need to enable it in this queue again.
+	 * The local_conf.offloads input to underlying PMD only carries
+	 * those offloadings which are only enabled on this queue and
+	 * not enabled on all queues.
+	 */
+	local_conf.offloads &= ~dev->data->dev_conf.rxmode.offloads;
+
+	/*
+	 * New added offloadings for this queue are those not enabled in
+	 * rte_eth_dev_configure() and they must be per-queue type.
+	 * A pure per-port offloading can't be enabled on a queue while
+	 * disabled on another queue. A pure per-port offloading can't
+	 * be enabled for any queue as new added one if it hasn't been
+	 * enabled in rte_eth_dev_configure().
+	 */
+	if ((local_conf.offloads & dev_info.rx_queue_offload_capa) !=
+	     local_conf.offloads) {
+		RTE_ETHDEV_LOG(ERR,
+			"Ethdev port_id=%d rx_queue_id=%d, new added offloads 0x%"PRIx64" must be "
+			"within per-queue offload capabilities 0x%"PRIx64" in %s()\n",
+			port_id, rx_queue_id, local_conf.offloads,
+			dev_info.rx_queue_offload_capa,
+			__func__);
+		return -EINVAL;
+	}
+
+	/*
+	 * If LRO is enabled, check that the maximum aggregated packet
+	 * size is supported by the configured device.
+	 */
+	if (local_conf.offloads & DEV_RX_OFFLOAD_TCP_LRO) {
+		if (dev->data->dev_conf.rxmode.max_lro_pkt_size == 0)
+			dev->data->dev_conf.rxmode.max_lro_pkt_size =
+				dev->data->dev_conf.rxmode.max_rx_pkt_len;
+		int ret = check_lro_pkt_size(port_id,
+				dev->data->dev_conf.rxmode.max_lro_pkt_size,
+				dev->data->dev_conf.rxmode.max_rx_pkt_len,
+				dev_info.max_lro_pkt_size);
+		if (ret != 0)
+			return ret;
+	}
+
+	ret = (*dev->dev_ops->rx_queue_setup_ex)(dev, rx_queue_id, nb_rx_desc,
+						 socket_id, &local_conf,
+						 rx_seg, n_seg);
+	if (!ret) {
+		if (!dev->data->min_rx_buf_size ||
+		    dev->data->min_rx_buf_size > mbp_buf_size)
+			dev->data->min_rx_buf_size = mbp_buf_size;
+	}
+
+	return eth_err(port_id, ret);
+}
+
+int
 rte_eth_rx_hairpin_queue_setup(uint16_t port_id, uint16_t rx_queue_id,
 			       uint16_t nb_rx_desc,
 			       const struct rte_eth_hairpin_conf *conf)
diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
index 70295d7..701264a 100644
--- a/lib/librte_ethdev/rte_ethdev.h
+++ b/lib/librte_ethdev/rte_ethdev.h
@@ -938,6 +938,16 @@ struct rte_eth_txmode {
 };
 
 /**
+ * A structure used to configure an RX packet segment to split.
+ */
+struct rte_eth_rxseg {
+	struct rte_mempool *mp; /**< Memory pools to allocate segment from */
+	uint16_t length; /**< Segment maximal data length */
+	uint16_t offset; /**< Data offset from beggining of mbuf data buffer */
+	uint32_t reserved; /**< Reserved field */
+};
+
+/**
  * A structure used to configure an RX ring of an Ethernet port.
  */
 struct rte_eth_rxconf {
@@ -1988,6 +1998,11 @@ int rte_eth_rx_queue_setup(uint16_t port_id, uint16_t rx_queue_id,
 		const struct rte_eth_rxconf *rx_conf,
 		struct rte_mempool *mb_pool);
 
+int rte_eth_rx_queue_setup_ex(uint16_t port_id, uint16_t rx_queue_id,
+		uint16_t nb_rx_desc, unsigned int socket_id,
+		const struct rte_eth_rxconf *rx_conf,
+		const struct rte_eth_rxseg *rx_seg, uint16_t n_seg);
+
 /**
  * @warning
  * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
diff --git a/lib/librte_ethdev/rte_ethdev_core.h b/lib/librte_ethdev/rte_ethdev_core.h
index 32407dd..27018de 100644
--- a/lib/librte_ethdev/rte_ethdev_core.h
+++ b/lib/librte_ethdev/rte_ethdev_core.h
@@ -265,6 +265,15 @@ typedef int (*eth_rx_queue_setup_t)(struct rte_eth_dev *dev,
 				    struct rte_mempool *mb_pool);
 /**< @internal Set up a receive queue of an Ethernet device. */
 
+typedef int (*eth_rx_queue_setup_ex_t)(struct rte_eth_dev *dev,
+				       uint16_t rx_queue_id,
+				       uint16_t nb_rx_desc,
+				       unsigned int socket_id,
+				       const struct rte_eth_rxconf *rx_conf,
+				       const struct rte_eth_rxseg *rx_seg,
+				       uint16_t n_seg);
+/**< @internal Set up a receive queue of an Ethernet device. */
+
 typedef int (*eth_tx_queue_setup_t)(struct rte_eth_dev *dev,
 				    uint16_t tx_queue_id,
 				    uint16_t nb_tx_desc,
@@ -659,6 +668,7 @@ struct eth_dev_ops {
 	eth_queue_start_t          tx_queue_start;/**< Start TX for a queue. */
 	eth_queue_stop_t           tx_queue_stop; /**< Stop TX for a queue. */
 	eth_rx_queue_setup_t       rx_queue_setup;/**< Set up device RX queue. */
+	eth_rx_queue_setup_ex_t    rx_queue_setup_ex;/**< Set up device RX queue. */
 	eth_queue_release_t        rx_queue_release; /**< Release RX queue. */
 	eth_rx_queue_count_t       rx_queue_count;
 	/**< Get the number of used RX descriptors. */
-- 
1.8.3.1


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