--- /dev/null
+.. BSD LICENSE
+ Copyright(c) 2010-2014 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.
+
+IXGBE Driver
+============
+
+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.
+
+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_ENABLE=y)
+
+
+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_ENABLE=y:
+
+.. 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_ENABLE=n, 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
+
+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.
+
+
+Malicious Driver Detection not Supported
+----------------------------------------
+
+The Intel x550 series NICs support a feature called MDD (Malicious
+Driver Detection) which checks the behavior of the VF driver.
+If this feature is enabled, the VF must use the advanced context descriptor
+correctly and set the CC (Check Context) bit.
+DPDK PF doesn't support MDD, but kernel PF does. We may hit problem in this
+scenario kernel PF + DPDK VF. If user enables MDD in kernel PF, DPDK VF will
+not work. Because kernel PF thinks the VF is malicious. But actually it's not.
+The only reason is the VF doesn't act as MDD required.
+There's significant performance impact to support MDD. DPDK should check if
+the advanced context descriptor should be set and set it. And DPDK has to ask
+the info about the header length from the upper layer, because parsing the
+packet itself is not acceptable. So, it's too expensive to support MDD.
+When using kernel PF + DPDK VF on x550, please make sure using the kernel
+driver that disables MDD or can disable MDD. (Some kernel driver can use
+this CLI 'insmod ixgbe.ko MDD=0,0' to disable MDD. Some kernel driver disables
+it by default.)
+
+
+Statistics
+----------
+
+The statistics of ixgbe hardware must be polled regularly in order for it to
+remain consistent. Running a DPDK application without polling the statistics will
+cause registers on hardware to count to the maximum value, and "stick" at
+that value.
+
+In order to avoid statistic registers every reaching the maximum value,
+read the statistics from the hardware using ``rte_eth_stats_get()`` or
+``rte_eth_xstats_get()``.
+
+The maximum time between statistics polls that ensures consistent results can
+be calculated as follows:
+
+.. code-block:: c
+
+ max_read_interval = UINT_MAX / max_packets_per_second
+ max_read_interval = 4294967295 / 14880952
+ max_read_interval = 288.6218096127183 (seconds)
+ max_read_interval = ~4 mins 48 sec.
+
+In order to ensure valid results, it is recommended to poll every 4 minutes.
Code Review / deb_dpdk.git / blobdiff