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diff --git a/doc/guides/nics/fm10k.rst b/doc/guides/nics/fm10k.rst new file mode 100644 index 00000000..c4915d82 --- /dev/null +++ b/doc/guides/nics/fm10k.rst @@ -0,0 +1,203 @@ +.. BSD LICENSE + Copyright(c) 2015-2016 Intel Corporation. All rights reserved. + All rights reserved. + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions + are met: + + * Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + * Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in + the documentation and/or other materials provided with the + distribution. + * Neither the name of Intel Corporation nor the names of its + contributors may be used to endorse or promote products derived + from this software without specific prior written permission. + + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +FM10K Poll Mode Driver +====================== + +The FM10K poll mode driver library provides support for the Intel FM10000 +(FM10K) family of 40GbE/100GbE adapters. + +FTAG Based Forwarding of FM10K +------------------------------ + +FTAG Based Forwarding is a unique feature of FM10K. The FM10K family of NICs +support the addition of a Fabric Tag (FTAG) to carry special information. +The FTAG is placed at the beginning of the frame, it contains information +such as where the packet comes from and goes, and the vlan tag. In FTAG based +forwarding mode, the switch logic forwards packets according to glort (global +resource tag) information, rather than the mac and vlan table. Currently this +feature works only on PF. + +To enable this feature, the user should pass a devargs parameter to the eal +like "-w 84:00.0,enable_ftag=1", and the application should make sure an +appropriate FTAG is inserted for every frame on TX side. + +Vector PMD for FM10K +-------------------- + +Vector PMD (vPMD) 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)''. +The wider register gives space to hold multiple packet buffers so as to save +on the number of instructions when bulk processing packets. + +There is no change to the PMD API. The RX/TX handlers are the only two entries for +vPMD packet I/O. They are transparently registered at runtime RX/TX execution +if all required conditions are met. + +1. To date, only an SSE version of FM10K vPMD is available. + To ensure that vPMD is in the binary code, set + ``CONFIG_RTE_LIBRTE_FM10K_INC_VECTOR=y`` 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 +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +For Vector RX it is assumed that the number of descriptor rings will be a power +of 2. With this pre-condition, the ring pointer can easily scroll back to the +head after hitting the tail without a conditional check. In addition Vector RX +can use this assumption to do a bit mask using ``ring_size - 1``. + + +Features not Supported by Vector RX PMD +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Some features are not supported when trying to increase the throughput in +vPMD. They are: + +* IEEE1588 + +* Flow director + +* Header split + +* RX checksum offload + +Other features are supported using optional MACRO configuration. They include: + +* HW VLAN strip + +* L3/L4 packet type + +To enable via ``RX_OLFLAGS`` use ``RTE_LIBRTE_FM10K_RX_OLFLAGS_ENABLE=y``. + +To guarantee the constraint, the following configuration flags in ``dev_conf.rxmode`` +will be checked: + +* ``hw_vlan_extend`` + +* ``hw_ip_checksum`` + +* ``header_split`` + +* ``fdir_conf->mode`` + + +RX Burst Size +^^^^^^^^^^^^^ + +As vPMD is focused on high throughput, it processes 4 packets at a time. So it assumes +that the RX burst should be greater than 4 packets per burst. It returns zero if using +``nb_pkt`` < 4 in the receive handler. If ``nb_pkt`` is not a multiple of 4, a +floor alignment will be applied. + + +TX Constraint +~~~~~~~~~~~~~ + +Features not Supported by TX Vector PMD +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +TX vPMD only works when ``txq_flags`` is set to ``FM10K_SIMPLE_TX_FLAG``. +This means that it does not support TX multi-segment, VLAN offload or 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`` + +Limitations +----------- + + +Switch manager +~~~~~~~~~~~~~~ + +The Intel FM10000 family of NICs integrate a hardware switch and multiple host +interfaces. The FM10000 PMD driver only manages host interfaces. For the +switch component another switch driver has to be loaded prior to to the +FM10000 PMD driver. The switch driver can be acquired for Intel support or +from the `Match Interface <https://github.com/match-interface>`_ project. +Only Testpoint is validated with DPDK, the latest version that has been +validated with DPDK2.2 is 4.1.6. + +CRC striping +~~~~~~~~~~~~ + +The FM10000 family of NICs strip the CRC for every packets coming into the +host interface. So, CRC will be stripped even when the +``rxmode.hw_strip_crc`` member is set to 0 in ``struct rte_eth_conf``. + + +Maximum packet length +~~~~~~~~~~~~~~~~~~~~~ + +The FM10000 family of NICS support a maximum of a 15K jumbo frame. The value +is fixed and cannot be changed. So, even when the ``rxmode.max_rx_pkt_len`` +member of ``struct rte_eth_conf`` is set to a value lower than 15364, frames +up to 15364 bytes can still reach the host interface. + +Statistic Polling Frequency +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The FM10000 NICs expose a set of statistics via the PCI BARs. These statistics +are read from the hardware registers when ``rte_eth_stats_get()`` or +``rte_eth_xstats_get()`` is called. The packet counting registers are 32 bits +while the byte counting registers are 48 bits. As a result, the statistics must +be polled regularly in order to ensure the consistency of the returned reads. + +Given the PCIe Gen3 x8, about 50Gbps of traffic can occur. With 64 byte packets +this gives almost 100 million packets/second, causing 32 bit integer overflow +after approx 40 seconds. To ensure these overflows are detected and accounted +for in the statistics, it is necessary to read statistic regularly. It is +suggested to read stats every 20 seconds, which will ensure the statistics +are accurate. + + +Interrupt mode +~~~~~~~~~~~~~~ + +The FM10000 family of NICS need one separate interrupt for mailbox. So only +drivers which support multiple interrupt vectors e.g. vfio-pci can work +for fm10k interrupt mode. |