[dpdk-dev] [PATCH v3] doc: add preferred burst size support

[Shreyansh Jain]

rte_eth_rx_burst(..,nb_pkts) function has semantic that if return value
is smaller than requested, application can consider it end of packet
stream. Some hardware can only support smaller burst sizes which need
to be advertised. Similar is the case for Tx burst.

This patch adds deprecation notice for rte_eth_dev_info structure as
new members, for preferred Rx and Tx burst and ring size would be
added - impacting the size of the structure.

Signed-off-by: Shreyansh Jain <shreyansh.jain at nxp.com>
Acked-by: Hemant Agrawal <hemant.agrawal at nxp.com>
Acked-by: Andrew Rybchenko <arybchenko at solarflare.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>
---
v3:
 Modification to deprecation notice to add ring size as member

v2:
 Spell check

 doc/guides/rel_notes/deprecation.rst | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index d59ad5988..91de3c62c 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -59,3 +59,16 @@ Deprecation Notices
   be added between the producer and consumer structures. The size of the
   structure and the offset of the fields will remain the same on
   platforms with 64B cache line, but will change on other platforms.
+
+* ethdev:  Currently, if the  rte_eth_rx_burst() function returns a value less
+  than *nb_pkts*, the application will assume that no more packets are present.
+  Some of the hw queue based hardware can only support smaller burst for RX
+  and TX and thus break the expectation of the rx_burst API. Similar is the
+  case for TX burst as well as ring sizes. ``rte_eth_dev_info`` will be added
+  with following new parameters so as to support semantics for drivers to
+  define a preferred size for Rx/Tx burst and rings.
+
+  - Member ``struct preferred_size`` would be added to enclose all preferred
+    size to be fetched from driver/implementation.
+  - Members ``uint16_t rx_burst``,  ``uint16_t tx_burst``, ``uint16_t rx_ring``,
+    and ``uint16_t tx_ring`` would be added to ``struct preferred_size``.
-- 
2.14.1