[PATCH v3] doc: update DLB2 documentation

[Abdullah Sevincer <abdullah.sevincer@intel.com>]

This commit updates the dlb2.rst eventdev guide to document a
new devarg. A new devarg: "default_port_allocation" added
to allow default ldb port allocation scheme.

Signed-off-by: Abdullah Sevincer <abdullah.sevincer@intel.com>
---
 doc/guides/eventdevs/dlb2.rst | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/doc/guides/eventdevs/dlb2.rst b/doc/guides/eventdevs/dlb2.rst
index 5b21f13b68..2a0bdacfbd 100644
--- a/doc/guides/eventdevs/dlb2.rst
+++ b/doc/guides/eventdevs/dlb2.rst
@@ -414,3 +414,22 @@ Note that the weight may not exceed the maximum CQ depth.
        --allow ea:00.0,cq_weight=all:<weight>
        --allow ea:00.0,cq_weight=qidA-qidB:<weight>
        --allow ea:00.0,cq_weight=qid:<weight>
+
+Default LDB Port Allocation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+For optimal load balancing ports that map to one or more QIDs in common
+should not be in numerical sequence. The port->QID mapping is application
+dependent, but the driver interleaves port IDs as much as possible to
+reduce the likelihood of sequential ports mapping to the same QID(s).
+
+Hence, DLB uses an initial allocation of Port IDs to maximize the
+average distance between an ID and its immediate neighbors. (i.e.the
+distance from 1 to 0 and to 2, the distance from 2 to 1 and to 3, etc.).
+Initial port allocation option can be passed through devarg. If y (or Y)
+inial port allocation will be used, otherwise initial port allocation
+won't be used.
+
+    .. code-block:: console
+
+       --allow ea:00.0,default_port_allocation=<y/Y>
-- 
2.25.1