[dpdk-dev] [PATCH v6 1/6] ethdev: introduce Rx buffer split
Viacheslav Ovsiienko
viacheslavo at nvidia.com
Wed Oct 14 20:11:57 CEST 2020
The DPDK datapath in the transmit direction is very flexible.
An application can build the multi-segment 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 information 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,
configures "split point" */
uint16_t offset; /* data offset from beginning
of mbuf data buffer */
uint32_t reserved; /* reserved field */
};
The segment descriptions are added to the rte_eth_rxconf structure:
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.
This array allows to specify the different settings for
each segment in individual fashion.
rx_nseg - number of elements in the array
If the extended segment descriptions is provided with these new
fields the mp parameter of the rte_eth_rx_queue_setup must be
specified as NULL to avoid ambiguity.
There are two options to specifiy Rx buffer configuration:
- mp is not NULL, rx_conf.rx_seg is NULL, rx_conf.rx_nseg is zero,
it is compatible configuraion, follows existing implementation,
provides single pool and no description for segment sizes
and offsets.
- mp is NULL, rx_conf.rx_seg is not NULL, rx_conf.rx_nseg is not
zero, it provides the extended configuration, individually for
each segment.
The new offload flag RTE_ETH_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() routine
application should check RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT flag.
If the Rx queue is configured with new settings the packets being
received will be split into multiple segments pushed to the mbufs
with specified attributes. The PMD will split the received packets
into multiple segments according to the specification in the
description array:
- the first network buffer will be allocated from the memory pool,
specified in the first segment description element, the second
network buffer - from the pool in the second segment description
element and so on. If there is no enough elements to describe
the buffer for entire packet of maximal length the pool from the
last valid element will be used to allocate the buffers from for the
rest of segments
- the offsets from the segment description elements will provide
the data offset from the buffer beginning except the first mbuf -
for this one the offset is added to the RTE_PKTMBUF_HEADROOM to get
actual offset from the buffer beginning. If there is no enough
elements to describe the buffer for entire packet of maximal length
the offsets for the rest of segment will be supposed to be zero.
- the data length being received to each segment is limited by the
length specified in the segment description element. The data
receiving starts with filling up the first mbuf data buffer, if the
specified maximal segment length is reached and there are data
remaining (packet is longer than buffer in the first mbuf) the
following data will be pushed to the next segment up to its own
maximal length. If the first two segments is not enough to store
all the packet remaining data the next (third) segment will
be engaged and so on. If the length in the segment description
element is zero the actual buffer size will be deduced from
the appropriate memory pool properties. If there is no enough
elements to describe the buffer for entire packet of maximal
length the buffer size will be deduced from the pool of the last
valid element for the remaining segments.
For example, let's suppose we configured the Rx queue with the
following segments:
seg0 - pool0, len0=14B, off0=2
seg1 - pool1, len1=20B, off1=128B
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 + 2 in mbuf from pool0
seg1 - 20B long @ 128 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 + 2 in mbuf from pool0
seg1 - 20B @ 128 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 RTE_ETH_RX_OFFLOAD_SCATTER must be present and
configured to support new buffer split feature (if rx_nseg
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.
Signed-off-by: Viacheslav Ovsiienko <viacheslavo at nvidia.com>
---
doc/guides/nics/features.rst | 15 +++++
doc/guides/rel_notes/deprecation.rst | 5 --
doc/guides/rel_notes/release_20_11.rst | 9 +++
lib/librte_ethdev/rte_ethdev.c | 111 +++++++++++++++++++++++++--------
lib/librte_ethdev/rte_ethdev.h | 62 +++++++++++++++++-
5 files changed, 171 insertions(+), 31 deletions(-)
diff --git a/doc/guides/nics/features.rst b/doc/guides/nics/features.rst
index dd8c955..832ea3b 100644
--- a/doc/guides/nics/features.rst
+++ b/doc/guides/nics/features.rst
@@ -185,6 +185,21 @@ Supports receiving segmented mbufs.
* **[related] eth_dev_ops**: ``rx_pkt_burst``.
+.. _nic_features_buffer_split:
+
+Buffer Split on Rx
+------------------
+
+Scatters the packets being received on specified boundaries to segmented mbufs.
+
+* **[uses] rte_eth_rxconf,rte_eth_rxmode**: ``offloads:RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT``.
+* **[uses] rte_eth_rxconf**: ``rx_conf.rx_seg, rx_conf.rx_nseg``.
+* **[implements] datapath**: ``Buffer Split functionality``.
+* **[provides] rte_eth_dev_info**: ``rx_offload_capa:RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT``.
+* **[provides] eth_dev_ops**: ``rxq_info_get:buffer_split``.
+* **[related] API**: ``rte_eth_rx_queue_setup()``.
+
+
.. _nic_features_lro:
LRO
diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 584e720..232cd54 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -138,11 +138,6 @@ Deprecation Notices
In 19.11 PMDs will still update the field even when the offload is not
enabled.
-* ethdev: Add new fields to ``rte_eth_rxconf`` to configure the receiving
- queues to split ingress packets into multiple segments according to the
- specified lengths into the buffers allocated from the specified
- memory pools. The backward compatibility to existing API is preserved.
-
* ethdev: ``rx_descriptor_done`` dev_ops and ``rte_eth_rx_descriptor_done``
will be removed in 21.11.
Existing ``rte_eth_rx_descriptor_status`` and ``rte_eth_tx_descriptor_status``
diff --git a/doc/guides/rel_notes/release_20_11.rst b/doc/guides/rel_notes/release_20_11.rst
index bcc0fc2..bcc2479 100644
--- a/doc/guides/rel_notes/release_20_11.rst
+++ b/doc/guides/rel_notes/release_20_11.rst
@@ -60,6 +60,12 @@ New Features
Added the FEC API which provides functions for query FEC capabilities and
current FEC mode from device. Also, API for configuring FEC mode is also provided.
+* **Introduced extended buffer description for receiving.**
+
+ Added the extended Rx buffer description for Rx queue setup routine
+ providing the individual settings for each Rx segment with maximal size,
+ buffer offset and memory pool to allocate data buffers from.
+
* **Updated Broadcom bnxt driver.**
Updated the Broadcom bnxt driver with new features and improvements, including:
@@ -253,6 +259,9 @@ API Changes
As the data of ``uint8_t`` will be truncated when queue number under
a TC is greater than 256.
+* ethdev: Added fields rx_seg and rx_nseg to rte_eth_rxconf structure
+ to provide extended description of the receiving buffer.
+
* vhost: Moved vDPA APIs from experimental to stable.
* rawdev: Added a structure size parameter to the functions
diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index 892c246..96ecb91 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -105,6 +105,9 @@ struct rte_eth_xstats_name_off {
#define RTE_RX_OFFLOAD_BIT2STR(_name) \
{ DEV_RX_OFFLOAD_##_name, #_name }
+#define RTE_ETH_RX_OFFLOAD_BIT2STR(_name) \
+ { RTE_ETH_RX_OFFLOAD_##_name, #_name }
+
static const struct {
uint64_t offload;
const char *name;
@@ -128,9 +131,11 @@ struct rte_eth_xstats_name_off {
RTE_RX_OFFLOAD_BIT2STR(SCTP_CKSUM),
RTE_RX_OFFLOAD_BIT2STR(OUTER_UDP_CKSUM),
RTE_RX_OFFLOAD_BIT2STR(RSS_HASH),
+ RTE_ETH_RX_OFFLOAD_BIT2STR(BUFFER_SPLIT),
};
#undef RTE_RX_OFFLOAD_BIT2STR
+#undef RTE_ETH_RX_OFFLOAD_BIT2STR
#define RTE_TX_OFFLOAD_BIT2STR(_name) \
{ DEV_TX_OFFLOAD_##_name, #_name }
@@ -1784,38 +1789,94 @@ struct rte_eth_dev *
return -EINVAL;
}
- if (mp == NULL) {
- RTE_ETHDEV_LOG(ERR, "Invalid null mempool pointer\n");
- return -EINVAL;
- }
-
RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_queue_setup, -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;
- 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 (mp) {
+ /* Single pool configuration check. */
+ if (rx_conf->rx_seg || rx_conf->rx_nseg) {
+ RTE_ETHDEV_LOG(ERR,
+ "Ambiguous segment configuration\n");
+ return -EINVAL;
+ }
+ /*
+ * 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(s) has a valid private data.
+ */
+ if (mp->private_data_size <
+ sizeof(struct rte_pktmbuf_pool_private)) {
+ RTE_ETHDEV_LOG(ERR, "%s private_data_size %u < %u\n",
+ mp->name, mp->private_data_size,
+ (unsigned int)
+ sizeof(struct rte_pktmbuf_pool_private));
+ return -ENOSPC;
+ }
+ mbp_buf_size = rte_pktmbuf_data_room_size(mp);
+ if (mbp_buf_size < dev_info.min_rx_bufsize +
+ RTE_PKTMBUF_HEADROOM) {
+ RTE_ETHDEV_LOG(ERR,
+ "%s mbuf_data_room_size %u < %u"
+ " (RTE_PKTMBUF_HEADROOM=%u +"
+ " min_rx_bufsize(dev)=%u)\n",
+ mp->name, mbp_buf_size,
+ RTE_PKTMBUF_HEADROOM +
+ dev_info.min_rx_bufsize,
+ RTE_PKTMBUF_HEADROOM,
+ dev_info.min_rx_bufsize);
+ return -EINVAL;
+ }
+ } else {
+ const struct rte_eth_rxseg *rx_seg = rx_conf->rx_seg;
+ uint16_t n_seg = rx_conf->rx_nseg;
+ uint16_t seg_idx;
- if (mbp_buf_size < dev_info.min_rx_bufsize + RTE_PKTMBUF_HEADROOM) {
- RTE_ETHDEV_LOG(ERR,
- "%s mbuf_data_room_size %d < %d (RTE_PKTMBUF_HEADROOM=%d + min_rx_bufsize(dev)=%d)\n",
- mp->name, (int)mbp_buf_size,
- (int)(RTE_PKTMBUF_HEADROOM + dev_info.min_rx_bufsize),
- (int)RTE_PKTMBUF_HEADROOM,
- (int)dev_info.min_rx_bufsize);
- return -EINVAL;
+ /* Extended multi-segment configuration check. */
+ if (!rx_conf->rx_seg || !rx_conf->rx_nseg) {
+ RTE_ETHDEV_LOG(ERR,
+ "Memory pool is null and no"
+ " extended configuration provided\n");
+ return -EINVAL;
+ }
+ /*
+ * Check the sizes and offsets against buffer sizes
+ * for each segment specified in extended configuration.
+ */
+ for (seg_idx = 0; seg_idx < n_seg; seg_idx++) {
+ struct rte_mempool *mpl = rx_seg[seg_idx].mp;
+ uint32_t length = rx_seg[seg_idx].length;
+ uint32_t offset = rx_seg[seg_idx].offset;
+ uint32_t head_room = seg_idx ? 0 : RTE_PKTMBUF_HEADROOM;
+
+ if (mpl == NULL) {
+ RTE_ETHDEV_LOG(ERR, "null mempool pointer\n");
+ return -EINVAL;
+ }
+ if (mpl->private_data_size <
+ sizeof(struct rte_pktmbuf_pool_private)) {
+ RTE_ETHDEV_LOG(ERR,
+ "%s private_data_size %u < %u\n",
+ mpl->name,
+ mpl->private_data_size,
+ (unsigned int)sizeof(struct
+ rte_pktmbuf_pool_private));
+ return -ENOSPC;
+ }
+ mbp_buf_size = rte_pktmbuf_data_room_size(mpl);
+ length = length ? length : (mbp_buf_size - head_room);
+ if (mbp_buf_size < length + offset + head_room) {
+ RTE_ETHDEV_LOG(ERR,
+ "%s mbuf_data_room_size %u < %u"
+ " (segment length=%u +"
+ " segment offset=%u)\n",
+ mpl->name, mbp_buf_size,
+ length + offset, length, offset);
+ return -EINVAL;
+ }
+ }
}
/* Use default specified by driver, if nb_rx_desc is zero */
diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
index 5bcfbb8..e019f4a 100644
--- a/lib/librte_ethdev/rte_ethdev.h
+++ b/lib/librte_ethdev/rte_ethdev.h
@@ -970,6 +970,16 @@ struct rte_eth_txmode {
};
/**
+ * A structure used to configure an RX packet segment to split.
+ */
+struct rte_eth_rxseg {
+ struct rte_mempool *mp; /**< Memory pool to allocate segment from. */
+ uint16_t length; /**< Segment data length, configures split point. */
+ uint16_t offset; /**< Data offset from beginning 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 {
@@ -977,6 +987,43 @@ struct rte_eth_rxconf {
uint16_t rx_free_thresh; /**< Drives the freeing of RX descriptors. */
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. */
+ /**
+ * Points to the array of segment descriptions. Each array element
+ * describes the properties for each segment in the receiving
+ * buffer.
+ *
+ * If RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT flag is set in offloads field,
+ * the PMD will split the received packets into multiple segments
+ * according to the specification in the description array:
+ *
+ * - the first network buffer will be allocated from the memory pool,
+ * specified in the first array element, the second buffer, from the
+ * pool in the second element, and so on.
+ *
+ * - the offsets from the segment description elements specify
+ * the data offset from the buffer beginning except the first mbuf.
+ * For this one the offset is added with RTE_PKTMBUF_HEADROOM.
+ *
+ * - the lengthes in the elements define the maximal data amount
+ * being received to each segment. The receiving starts with filling
+ * up the first mbuf data buffer up to specified length. If the
+ * there are data remaining (packet is longer than buffer in the first
+ * mbuf) the following data will be pushed to the next segment
+ * up to its own length, and so on.
+ *
+ * - If the length in the segment description element is zero
+ * the actual buffer size will be deduced from the appropriate
+ * memory pool properties.
+ *
+ * - if there is not enough elements to describe the buffer for entire
+ * packet of maximal length the following parameters will be used
+ * for the all remaining segments:
+ * - pool from the last valid element
+ * - the buffer size from this pool
+ * - zero offset
+ */
+ struct rte_eth_rxseg *rx_seg;
/**
* Per-queue Rx offloads to be set using DEV_RX_OFFLOAD_* flags.
* Only offloads set on rx_queue_offload_capa or rx_offload_capa
@@ -1260,6 +1307,7 @@ struct rte_eth_conf {
#define DEV_RX_OFFLOAD_SCTP_CKSUM 0x00020000
#define DEV_RX_OFFLOAD_OUTER_UDP_CKSUM 0x00040000
#define DEV_RX_OFFLOAD_RSS_HASH 0x00080000
+#define RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT 0x00100000
#define DEV_RX_OFFLOAD_CHECKSUM (DEV_RX_OFFLOAD_IPV4_CKSUM | \
DEV_RX_OFFLOAD_UDP_CKSUM | \
@@ -2027,9 +2075,21 @@ int rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_queue,
* No need to repeat any bit in rx_conf->offloads which has already been
* enabled in rte_eth_dev_configure() at port level. An offloading enabled
* at port level can't be disabled at queue level.
+ * The configuration structure also contains the pointer to the array
+ * of the receiving buffer segment descriptions, see rx_seg and rx_nseg
+ * fields, this extended configuration might be used by split offloads like
+ * RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT. If mp_pool is not NULL,
+ * the extended configuration fields must be set to NULL and zero.
* @param mb_pool
* The pointer to the memory pool from which to allocate *rte_mbuf* network
- * memory buffers to populate each descriptor of the receive ring.
+ * memory buffers to populate each descriptor of the receive ring. There are
+ * two options to provide Rx buffer configuration:
+ * - single pool:
+ * mb_pool is not NULL, rx_conf.rx_seg is NULL, rx_conf.rx_nseg is 0.
+ * - multiple segments description:
+ * mb_pool is NULL, rx_conf.rx_seg is not NULL, rx_conf.rx_nseg is not 0.
+ * Taken only if flag RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT is set in offloads.
+ *
* @return
* - 0: Success, receive queue correctly set up.
* - -EIO: if device is removed.
--
1.8.3.1
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