net/virtio: move PCI device ids to the driver

[dpdk.git] / doc / guides / prog_guide / poll_mode_drv.rst

diff --git a/doc/guides/prog_guide/poll_mode_drv.rst b/doc/guides/prog_guide/poll_mode_drv.rst
index 8780ba3..bf3ea9f 100644 (file)
--- a/doc/guides/prog_guide/poll_mode_drv.rst
+++ b/doc/guides/prog_guide/poll_mode_drv.rst
@@ -1,5 +1,5 @@
 ..  BSD LICENSE
-    Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+    Copyright(c) 2010-2015 Intel Corporation. All rights reserved.
     All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
@@ -294,3 +294,65 @@ Ethernet Device API
 ~~~~~~~~~~~~~~~~~~~
 
 The Ethernet device API exported by the Ethernet PMDs is described in the *DPDK API Reference*.
+
+Extended Statistics API
+~~~~~~~~~~~~~~~~~~~~~~~
+
+The extended statistics API allows each individual PMD to expose a unique set
+of statistics. Accessing these from application programs is done via two
+functions:
+
+* ``rte_eth_xstats_get``: Fills in an array of ``struct rte_eth_xstat``
+  with extended statistics.
+* ``rte_eth_xstats_get_names``: Fills in an array of
+  ``struct rte_eth_xstat_name`` with extended statistic name lookup
+  information.
+
+Each ``struct rte_eth_xstat`` contains an identifier and value pair, and
+each ``struct rte_eth_xstat_name`` contains a string. Each identifier
+within the ``struct rte_eth_xstat`` lookup array must have a corresponding
+entry in the ``struct rte_eth_xstat_name`` lookup array. Within the latter
+the index of the entry is the identifier the string is associated with.
+These identifiers, as well as the number of extended statistic exposed, must
+remain constant during runtime. Note that extended statistic identifiers are
+driver-specific, and hence might not be the same for different ports.
+
+A naming scheme exists for the strings exposed to clients of the API. This is
+to allow scraping of the API for statistics of interest. The naming scheme uses
+strings split by a single underscore ``_``. The scheme is as follows:
+
+* direction
+* detail 1
+* detail 2
+* detail n
+* unit
+
+Examples of common statistics xstats strings, formatted to comply to the scheme
+proposed above:
+
+* ``rx_bytes``
+* ``rx_crc_errors``
+* ``tx_multicast_packets``
+
+The scheme, although quite simple, allows flexibility in presenting and reading
+information from the statistic strings. The following example illustrates the
+naming scheme:``rx_packets``. In this example, the string is split into two
+components. The first component ``rx`` indicates that the statistic is
+associated with the receive side of the NIC.  The second component ``packets``
+indicates that the unit of measure is packets.
+
+A more complicated example: ``tx_size_128_to_255_packets``. In this example,
+``tx`` indicates transmission, ``size``  is the first detail, ``128`` etc are
+more details, and ``packets`` indicates that this is a packet counter.
+
+Some additions in the metadata scheme are as follows:
+
+* If the first part does not match ``rx`` or ``tx``, the statistic does not
+  have an affinity with either receive of transmit.
+
+* If the first letter of the second part is ``q`` and this ``q`` is followed
+  by a number, this statistic is part of a specific queue.
+
+An example where queue numbers are used is as follows: ``tx_q7_bytes`` which
+indicates this statistic applies to queue number 7, and represents the number
+of transmitted bytes on that queue.