+
+
+Netvsc PMD arguments
+--------------------
+
+The user can specify below argument in devargs.
+
+#. ``latency``:
+
+ A netvsc device uses a mailbox page to indicate to the host that there
+ is something in the transmit queue. The host scans this page at a
+ periodic interval. This parameter allows adjusting the value that
+ is used by the host. Smaller values improve transmit latency, and larger
+ values save CPU cycles. This parameter is in microseconds.
+ If the value is too large or too small it will be
+ ignored by the host. (Default: 50)
+
+#. ``rx_copybreak``:
+
+ The rx_copybreak sets the threshold where the driver uses an external
+ mbuf to avoid having to copy data. Setting 0 for copybreak will cause
+ driver to always create an external mbuf. Setting a value greater than
+ the MTU would prevent it from ever making an external mbuf and always
+ copy. The default value is 256 (bytes).
+
+#. ``tx_copybreak``:
+
+ The tx_copybreak sets the threshold where the driver aggregates
+ multiple small packets into one request. If tx_copybreak is 0 then
+ each packet goes as a VMBus request (no copying). If tx_copybreak is
+ set larger than the MTU, then all packets smaller than the chunk size
+ of the VMBus send buffer will be copied; larger packets always have to
+ go as a single direct request. The default value is 512 (bytes).
+
+#. ``rx_extmbuf_enable``:
+ The rx_extmbuf_enable is used to control if netvsc should use external
+ mbuf for receiving packets. The default value is 0. (netvsc doesn't use
+ external mbuf, it always allocates mbuf and copy received data to mbuf)
+ A non-zero value tells netvsc to attach external buffers to mbuf on
+ receiving packets, thus avoid copying memory. Use of external buffers
+ requires the application is able to read data from external mbuf.