Virtio PMD Rx/Tx Callbacks
--------------------------
-Virtio driver has 3 Rx callbacks and 2 Tx callbacks.
+Virtio driver has 4 Rx callbacks and 3 Tx callbacks.
Rx callbacks:
Vector version without mergeable Rx buffer support, also fixes the available
ring indexes and uses vector instructions to optimize performance.
+#. ``virtio_recv_mergeable_pkts_inorder``:
+ In-order version with mergeable Rx buffer support.
+
Tx callbacks:
#. ``virtio_xmit_pkts``:
#. ``virtio_xmit_pkts_simple``:
Vector version fixes the available ring indexes to optimize performance.
+#. ``virtio_xmit_pkts_inorder``:
+ In-order version.
By default, the non-vector callbacks are used:
testpmd -l 0-2 -n 4 -- -i --tx-offloads=0x0 --rxq=1 --txq=1 --nb-cores=1
+In-order callbacks only work on simulated virtio user vdev.
+
+* For Rx: If mergeable Rx buffers is enabled and in-order is enabled then
+ ``virtio_xmit_pkts_inorder`` is used.
+
+* For Tx: If in-order is enabled then ``virtio_xmit_pkts_inorder`` is used.
Interrupt mode
--------------