-Vector PMD for IXGBE
---------------------
-
-Vector PMD uses Intel® SIMD instructions to optimize packet I/O.
-It improves load/store bandwidth efficiency of L1 data cache by using a wider SSE/AVX register 1 (1).
-The wider register gives space to hold multiple packet buffers so as to save instruction number when processing bulk of packets.
-
-There is no change to PMD API. The RX/TX handler are the only two entries for vPMD packet I/O.
-They are transparently registered at runtime RX/TX execution if all condition checks pass.
-
-1. To date, only an SSE version of IX GBE vPMD is available.
- To ensure that vPMD is in the binary code, ensure that the option CONFIG_RTE_IXGBE_INC_VECTOR=y is in the configure file.
-
-Some constraints apply as pre-conditions for specific optimizations on bulk packet transfers.
-The following sections explain RX and TX constraints in the vPMD.
-
-RX Constraints
-~~~~~~~~~~~~~~
-
-Prerequisites and Pre-conditions
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-The following prerequisites apply:
-
-* To enable vPMD to work for RX, bulk allocation for Rx must be allowed.
-
-* The RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC=y configuration MACRO must be set before compiling the code.
-
-Ensure that the following pre-conditions are satisfied:
-
-* rxq->rx_free_thresh >= RTE_PMD_IXGBE_RX_MAX_BURST
-
-* rxq->rx_free_thresh < rxq->nb_rx_desc
-
-* (rxq->nb_rx_desc % rxq->rx_free_thresh) == 0
-
-* rxq->nb_rx_desc < (IXGBE_MAX_RING_DESC - RTE_PMD_IXGBE_RX_MAX_BURST)
-
-These conditions are checked in the code.
-
-Scattered packets are not supported in this mode.
-If an incoming packet is greater than the maximum acceptable length of one "mbuf" data size (by default, the size is 2 KB),
-vPMD for RX would be disabled.
-
-By default, IXGBE_MAX_RING_DESC is set to 4096 and RTE_PMD_IXGBE_RX_MAX_BURST is set to 32.
-
-Feature not Supported by RX Vector PMD
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Some features are not supported when trying to increase the throughput in vPMD.
-They are:
-
-* IEEE1588
-
-* FDIR
-
-* Header split
-
-* RX checksum off load
-
-Other features are supported using optional MACRO configuration. They include:
-
-* HW VLAN strip
-
-* HW extend dual VLAN
-
-* Enabled by RX_OLFLAGS (RTE_IXGBE_RX_OLFLAGS_DISABLE=n)
-
-
-To guarantee the constraint, configuration flags in dev_conf.rxmode will be checked:
-
-* hw_vlan_strip
-
-* hw_vlan_extend
-
-* hw_ip_checksum
-
-* header_split
-
-* dev_conf
-
-fdir_conf->mode will also be checked.
-
-RX Burst Size
-^^^^^^^^^^^^^
-
-As vPMD is focused on high throughput, it assumes that the RX burst size is equal to or greater than 32 per burst.
-It returns zero if using nb_pkt < 32 as the expected packet number in the receive handler.
-
-TX Constraint
-~~~~~~~~~~~~~
-
-Prerequisite
-^^^^^^^^^^^^
-
-The only prerequisite is related to tx_rs_thresh.
-The tx_rs_thresh value must be greater than or equal to RTE_PMD_IXGBE_TX_MAX_BURST,
-but less or equal to RTE_IXGBE_TX_MAX_FREE_BUF_SZ.
-Consequently, by default the tx_rs_thresh value is in the range 32 to 64.
-
-Feature not Supported by RX Vector PMD
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-TX vPMD only works when txq_flags is set to IXGBE_SIMPLE_FLAGS.
-
-This means that it does not support TX multi-segment, VLAN offload and TX csum offload.
-The following MACROs are used for these three features:
-
-* ETH_TXQ_FLAGS_NOMULTSEGS
-
-* ETH_TXQ_FLAGS_NOVLANOFFL
-
-* ETH_TXQ_FLAGS_NOXSUMSCTP
-
-* ETH_TXQ_FLAGS_NOXSUMUDP
-
-* ETH_TXQ_FLAGS_NOXSUMTCP
-
-
-Sample Application Notes
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-testpmd
-^^^^^^^
-
-By default, using CONFIG_RTE_IXGBE_RX_OLFLAGS_DISABLE=n:
-
-.. code-block:: console
-
- ./x86_64-native-linuxapp-gcc/app/testpmd -c 300 -n 4 -- -i --burst=32 --rxfreet=32 --mbcache=250 --txpt=32 --rxht=8 --rxwt=0 --txfreet=32 --txrst=32 --txqflags=0xf01
-
-When CONFIG_RTE_IXGBE_RX_OLFLAGS_DISABLE=y, better performance can be achieved:
-
-.. code-block:: console
-
- ./x86_64-native-linuxapp-gcc/app/testpmd -c 300 -n 4 -- -i --burst=32 --rxfreet=32 --mbcache=250 --txpt=32 --rxht=8 --rxwt=0 --txfreet=32 --txrst=32 --txqflags=0xf01 --disable-hw-vlan
-
-If scatter gather lists are not required, set CONFIG_RTE_MBUF_SCATTER_GATHER=n for better throughput.
-
-l3fwd
-^^^^^
-
-When running l3fwd with vPMD, there is one thing to note.
-In the configuration, ensure that port_conf.rxmode.hw_ip_checksum=0.
-Otherwise, by default, RX vPMD is disabled.
-
-load_balancer
-^^^^^^^^^^^^^
-
-As in the case of l3fwd, set configure port_conf.rxmode.hw_ip_checksum=0 to enable vPMD.
-In addition, for improved performance, use -bsz "(32,32),(64,64),(32,32)" in load_balancer to avoid using the default burst size of 144.
+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.
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