From: Gregory Etelson <[email protected]>
Receiving an entire packet is not always needed.
The Rx performance can be improved by receiving only partial data
and safely discard the rest of the packet data,
because it reduces the PCI bandwidth and the memory consumption.
Selective Rx allows an application to receive
only pre-configured packet segments and discard the rest.
For example:
- Deliver the first N bytes only.
- Deliver the last N bytes only.
- Deliver N1 bytes from offset Off1 and N2 bytes from offset Off2.
Selective Rx is implemented on top of the Rx buffer split API:
- rte_eth_rxseg_split uses the null mempool for segments
that should be discarded.
- the PMD does not create mbuf segments if no data read.
For example: Deliver Ethernet header only
Rx queue segments configuration:
struct rte_eth_rxseg_split split[2] = {
{
.mp = <some mempool>,
.length = sizeof(struct rte_ether_hdr)
},
{
.mp = NULL, /* discard data */
.length = 0 /* default to buffer size */
}
};
Received mbuf:
pkt_len = sizeof(struct rte_ether_hdr);
data_len = sizeof(struct rte_ether_hdr);
next = NULL; /* The next segment did not deliver data */
After selective Rx, the mbuf packet length reflects only the data
that was actually received,
and can be less than the original wire packet length.
A PMD activates the selective Rx capability by setting
the rte_eth_rxseg_capa.selective_rx bit.
This new capability bit is inserted in a bitmap hole
of the struct rte_eth_rxseg_capa,
but it needs to be ignored in the ABI check as libabigail sees a change.
Signed-off-by: Gregory Etelson <[email protected]>
Signed-off-by: Thomas Monjalon <[email protected]>
---
app/test-pmd/config.c | 1 +
devtools/libabigail.abignore | 7 +++++++
doc/guides/nics/features.rst | 14 ++++++++++++++
doc/guides/nics/features/default.ini | 1 +
doc/guides/rel_notes/release_26_07.rst | 7 +++++++
lib/ethdev/rte_ethdev.c | 24 ++++++++++++++++--------
lib/ethdev/rte_ethdev.h | 14 +++++++++++++-
7 files changed, 59 insertions(+), 9 deletions(-)
diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
index af725fb74e..ce8e836fff 100644
--- a/app/test-pmd/config.c
+++ b/app/test-pmd/config.c
@@ -925,6 +925,7 @@ port_infos_display(portid_t port_id)
print_bool_capa("\tBuffer offset",
dev_info.rx_seg_capa.offset_allowed);
printf("\tOffset alignment: %u\n",
RTE_BIT32(dev_info.rx_seg_capa.offset_align_log2));
+ print_bool_capa("\tSelective Rx",
dev_info.rx_seg_capa.selective_rx);
}
if (dev_info.max_vfs)
diff --git a/devtools/libabigail.abignore b/devtools/libabigail.abignore
index 21b8cd6113..2a0efd718e 100644
--- a/devtools/libabigail.abignore
+++ b/devtools/libabigail.abignore
@@ -33,3 +33,10 @@
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Temporary exceptions till next major ABI version ;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; Ignore new bit selective_rx in rte_eth_rxseg_capa bitmap hole
+[suppress_type]
+ name = rte_eth_rxseg_capa
+ type_kind = struct
+ has_size_change = no
+ has_data_member_inserted_at = 6
diff --git a/doc/guides/nics/features.rst b/doc/guides/nics/features.rst
index a075c057ec..26357036ca 100644
--- a/doc/guides/nics/features.rst
+++ b/doc/guides/nics/features.rst
@@ -199,6 +199,20 @@ Scatters the packets being received on specified
boundaries to segmented mbufs.
* **[related] API**: ``rte_eth_rx_queue_setup()``,
``rte_eth_buffer_split_get_supported_hdr_ptypes()``.
+.. _nic_features_selective_rx:
+
+Selective Rx
+------------
+
+Discards some segments of buffer split on Rx.
+
+* **[uses] rte_eth_rxconf,rte_eth_rxmode**:
``offloads:RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT``.
+* **[uses] rte_eth_rxconf**: ``rx_seg.mp = NULL`` to discard segments.
+* **[provides] rte_eth_dev_info**:
``rx_offload_capa:RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT``.
+* **[provides] rte_eth_dev_info**: ``rx_seg_capa.selective_rx``.
+* **[related] API**: ``rte_eth_rx_queue_setup()``.
+
+
.. _nic_features_lro:
LRO
diff --git a/doc/guides/nics/features/default.ini
b/doc/guides/nics/features/default.ini
index e50514d750..8303a530c1 100644
--- a/doc/guides/nics/features/default.ini
+++ b/doc/guides/nics/features/default.ini
@@ -25,6 +25,7 @@ Burst mode info =
Power mgmt address monitor =
MTU update =
Buffer split on Rx =
+Selective Rx =
Scattered Rx =
LRO =
TSO =
diff --git a/doc/guides/rel_notes/release_26_07.rst
b/doc/guides/rel_notes/release_26_07.rst
index f012d47a4b..5f53d93558 100644
--- a/doc/guides/rel_notes/release_26_07.rst
+++ b/doc/guides/rel_notes/release_26_07.rst
@@ -63,6 +63,13 @@ New Features
``rte_eal_init`` and the application is responsible for probing each
device,
* ``--auto-probing`` enables the initial bus probing, which is the current
default behavior.
+* **Added selective Rx in ethdev API.**
+
+ Some parts of packets may be discarded in Rx
+ by configuring a split of packets received in a queue,
+ and assigning no mempool to some configuration segments.
+ This is a driver capability advertised in the ``selective_rx`` bit.
+
Removed Items
-------------
diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
index 2edc7a362e..03aa400e86 100644
--- a/lib/ethdev/rte_ethdev.c
+++ b/lib/ethdev/rte_ethdev.c
@@ -2129,7 +2129,7 @@ rte_eth_rx_queue_check_split(uint16_t port_id,
const struct rte_eth_dev_info *dev_info)
{
const struct rte_eth_rxseg_capa *seg_capa = &dev_info->rx_seg_capa;
- struct rte_mempool *mp_first;
+ struct rte_mempool *mp_first = NULL;
uint32_t offset_mask;
uint16_t seg_idx;
int ret = 0;
@@ -2148,7 +2148,6 @@ rte_eth_rx_queue_check_split(uint16_t port_id,
* Check the sizes and offsets against buffer sizes
* for each segment specified in extended configuration.
*/
- mp_first = rx_seg[0].mp;
offset_mask = RTE_BIT32(seg_capa->offset_align_log2) - 1;
ptypes = NULL;
@@ -2160,13 +2159,17 @@ rte_eth_rx_queue_check_split(uint16_t port_id,
uint32_t offset = rx_seg[seg_idx].offset;
uint32_t proto_hdr = rx_seg[seg_idx].proto_hdr;
- if (mpl == NULL) {
- RTE_ETHDEV_LOG_LINE(ERR, "null mempool pointer");
- ret = -EINVAL;
- goto out;
+ if (mpl == NULL) { /* discarded segment */
+ if (seg_capa->selective_rx == 0) { /* not supported */
+ RTE_ETHDEV_LOG_LINE(ERR, "null mempool
pointer");
+ ret = -EINVAL;
+ goto out;
+ }
+ continue; /* next checks are not relevant if no mempool
*/
}
- if (seg_idx != 0 && mp_first != mpl &&
- seg_capa->multi_pools == 0) {
+ if (mp_first == NULL)
+ mp_first = mpl;
+ if (mp_first != mpl && seg_capa->multi_pools == 0) {
RTE_ETHDEV_LOG_LINE(ERR, "Receiving to multiple pools
is not supported");
ret = -ENOTSUP;
goto out;
@@ -2233,6 +2236,11 @@ rte_eth_rx_queue_check_split(uint16_t port_id,
if (ret != 0)
goto out;
}
+ if (mp_first == NULL) {
+ RTE_ETHDEV_LOG_LINE(ERR, "At least one Rx segment must have a
mempool");
+ ret = -EINVAL;
+ goto out;
+ }
out:
free(ptypes);
return ret;
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index 0d8e2d0236..51f01c496a 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -1073,6 +1073,7 @@ struct rte_eth_txmode {
* - 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.
+ * If the pool is NULL, the segment will be discarded, i.e. not received.
*
* - The proto_hdrs in the elements define the split position of
* received packets.
@@ -1121,7 +1122,15 @@ struct rte_eth_txmode {
* The rest will be put into the last valid pool.
*/
struct rte_eth_rxseg_split {
- struct rte_mempool *mp; /**< Memory pool to allocate segment from. */
+ /**
+ * Memory pool to allocate segment from.
+ *
+ * NULL means discarded segment.
+ * Length of discarded segment is not reflected in mbuf packet length
+ * and not accounted in ibytes statistics.
+ * @see rte_eth_rxseg_capa::selective_rx
+ */
+ struct rte_mempool *mp;
uint16_t length; /**< Segment data length, configures split point. */
uint16_t offset; /**< Data offset from beginning of mbuf data buffer. */
/**
@@ -1752,12 +1761,15 @@ struct rte_eth_switch_info {
* @b EXPERIMENTAL: this structure may change without prior notice.
*
* Ethernet device Rx buffer segmentation capabilities.
+ *
+ * @see rte_eth_rxseg_split
*/
struct rte_eth_rxseg_capa {
__extension__
uint32_t multi_pools:1; /**< Supports receiving to multiple pools.*/
uint32_t offset_allowed:1; /**< Supports buffer offsets. */
uint32_t offset_align_log2:4; /**< Required offset alignment. */
+ uint32_t selective_rx:1; /**< Supports discarding segment. */
uint16_t max_nseg; /**< Maximum amount of segments to split. */
uint16_t reserved; /**< Reserved field. */
};
--
2.54.0
