doc: Move vhost tx retry info to separate section.

vhost tx retry is applicable to vhost-user and vhost-user-client,
but was in the section that compares them. Also, moved further
down the doc as prefer to have more fundamental info about vhost
nearer the top.

Fixes: 6d6513bfc657 ("doc: Add info on vhost tx retries.")
Reported-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>

diff --git a/Documentation/topics/dpdk/vhost-user.rst b/Documentation/topics/dpdk/vhost-user.rst
index a6cf9d1ccdf7e09040e2844fc03e2b255690a837..5f393aced8f3687a275ed7b0e47dcefe2d153e65 100644 (file)
--- a/Documentation/topics/dpdk/vhost-user.rst
+++ b/Documentation/topics/dpdk/vhost-user.rst
@@ -75,42 +75,6 @@ type for all known use cases; the only limitation is that vhost-user client
 mode ports require QEMU version 2.7.  Ports of type vhost-user are currently
 deprecated and will be removed in a future release.
 
-vhost tx retries
-~~~~~~~~~~~~~~~~
-
-When sending a batch of packets to a vhost-user or vhost-user-client interface,
-it may happen that some but not all of the packets in the batch are able to be
-sent to the guest. This is often because there is not enough free descriptors
-in the virtqueue for all the packets in the batch to be sent. In this case
-there will be a retry, with a default maximum of 8 occurring. If at any time no
-packets can be sent, it may mean the guest is not accepting packets, so there
-are no (more) retries.
-
-.. note::
-
-  Maximum vhost tx batch size is defined by NETDEV_MAX_BURST, and is currently
-  as 32.
-
-Tx Retries may be reduced or even avoided by some external configuration, such
-as increasing the virtqueue size through the ``rx_queue_size`` parameter
-introduced in QEMU 2.7.0 / libvirt 2.3.0::
-
-  <interface type='vhostuser'>
-      <mac address='56:48:4f:53:54:01'/>
-      <source type='unix' path='/tmp/dpdkvhostclient0' mode='server'/>
-      <model type='virtio'/>
-      <driver name='vhost' rx_queue_size='1024' tx_queue_size='1024'/>
-      <address type='pci' domain='0x0000' bus='0x00' slot='0x10' function='0x0'/>
-  </interface>
-
-The guest application will also need need to provide enough descriptors. For
-example with ``testpmd`` the command line argument can be used::
-
- --rxd=1024 --txd=1024
-
-The guest should also have sufficient cores dedicated for consuming and
-processing packets at the required rate.
-
 .. _dpdk-vhost-user:
 
 vhost-user
@@ -520,6 +484,42 @@ Jumbo Frames
 DPDK vHost User ports can be configured to use Jumbo Frames. For more
 information, refer to :doc:`jumbo-frames`.
 
+vhost tx retries
+----------------
+
+When sending a batch of packets to a vhost-user or vhost-user-client interface,
+it may happen that some but not all of the packets in the batch are able to be
+sent to the guest. This is often because there is not enough free descriptors
+in the virtqueue for all the packets in the batch to be sent. In this case
+there will be a retry, with a default maximum of 8 occurring. If at any time no
+packets can be sent, it may mean the guest is not accepting packets, so there
+are no (more) retries.
+
+.. note::
+
+  Maximum vhost tx batch size is defined by NETDEV_MAX_BURST, and is currently
+  as 32.
+
+Tx Retries may be reduced or even avoided by some external configuration, such
+as increasing the virtqueue size through the ``rx_queue_size`` parameter
+introduced in QEMU 2.7.0 / libvirt 2.3.0::
+
+  <interface type='vhostuser'>
+      <mac address='56:48:4f:53:54:01'/>
+      <source type='unix' path='/tmp/dpdkvhostclient0' mode='server'/>
+      <model type='virtio'/>
+      <driver name='vhost' rx_queue_size='1024' tx_queue_size='1024'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x10' function='0x0'/>
+  </interface>
+
+The guest application will also need need to provide enough descriptors. For
+example with ``testpmd`` the command line argument can be used::
+
+ --rxd=1024 --txd=1024
+
+The guest should also have sufficient cores dedicated for consuming and
+processing packets at the required rate.
+
 vhost-user Dequeue Zero Copy (experimental)
 -------------------------------------------