35b09d76f8
The coremask option in DPDK is difficult to use and we should be promoting the use of the corelist (-l) option. The patch adjusts the docs to use -l EAL option instead of the -c option. The patch only changes the docs and not the code as the -c option will continue to exist unless it is removed in the future. The -c option should be kept to maintain backward compatibility. Signed-off-by: Keith Wiles <keith.wiles@intel.com> Acked-by: John McNamara <john.mcnamara@intel.com>
244 lines
12 KiB
ReStructuredText
244 lines
12 KiB
ReStructuredText
.. 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.
|
|
|
|
Load Balancer Sample Application
|
|
================================
|
|
|
|
The Load Balancer sample application demonstrates the concept of isolating the packet I/O task
|
|
from the application-specific workload.
|
|
Depending on the performance target,
|
|
a number of logical cores (lcores) are dedicated to handle the interaction with the NIC ports (I/O lcores),
|
|
while the rest of the lcores are dedicated to performing the application processing (worker lcores).
|
|
The worker lcores are totally oblivious to the intricacies of the packet I/O activity and
|
|
use the NIC-agnostic interface provided by software rings to exchange packets with the I/O cores.
|
|
|
|
Overview
|
|
--------
|
|
|
|
The architecture of the Load Balance application is presented in the following figure.
|
|
|
|
.. _figure_load_bal_app_arch:
|
|
|
|
.. figure:: img/load_bal_app_arch.*
|
|
|
|
Load Balancer Application Architecture
|
|
|
|
|
|
For the sake of simplicity, the diagram illustrates a specific case of two I/O RX and two I/O TX lcores off loading the packet I/O
|
|
overhead incurred by four NIC ports from four worker cores, with each I/O lcore handling RX/TX for two NIC ports.
|
|
|
|
I/O RX Logical Cores
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Each I/O RX lcore performs packet RX from its assigned NIC RX rings and then distributes the received packets to the worker threads.
|
|
The application allows each I/O RX lcore to communicate with any of the worker threads,
|
|
therefore each (I/O RX lcore, worker lcore) pair is connected through a dedicated single producer - single consumer software ring.
|
|
|
|
The worker lcore to handle the current packet is determined by reading a predefined 1-byte field from the input packet:
|
|
|
|
worker_id = packet[load_balancing_field] % n_workers
|
|
|
|
Since all the packets that are part of the same traffic flow are expected to have the same value for the load balancing field,
|
|
this scheme also ensures that all the packets that are part of the same traffic flow are directed to the same worker lcore (flow affinity)
|
|
in the same order they enter the system (packet ordering).
|
|
|
|
I/O TX Logical Cores
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Each I/O lcore owns the packet TX for a predefined set of NIC ports. To enable each worker thread to send packets to any NIC TX port,
|
|
the application creates a software ring for each (worker lcore, NIC TX port) pair,
|
|
with each I/O TX core handling those software rings that are associated with NIC ports that it handles.
|
|
|
|
Worker Logical Cores
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Each worker lcore reads packets from its set of input software rings and
|
|
routes them to the NIC ports for transmission by dispatching them to output software rings.
|
|
The routing logic is LPM based, with all the worker threads sharing the same LPM rules.
|
|
|
|
Compiling the Application
|
|
-------------------------
|
|
|
|
The sequence of steps used to build the application is:
|
|
|
|
#. Export the required environment variables:
|
|
|
|
.. code-block:: console
|
|
|
|
export RTE_SDK=<Path to the DPDK installation folder>
|
|
export RTE_TARGET=x86_64-native-linuxapp-gcc
|
|
|
|
#. Build the application executable file:
|
|
|
|
.. code-block:: console
|
|
|
|
cd ${RTE_SDK}/examples/load_balancer
|
|
make
|
|
|
|
For more details on how to build the DPDK libraries and sample applications,
|
|
please refer to the *DPDK Getting Started Guide.*
|
|
|
|
Running the Application
|
|
-----------------------
|
|
|
|
To successfully run the application,
|
|
the command line used to start the application has to be in sync with the traffic flows configured on the traffic generator side.
|
|
|
|
For examples of application command lines and traffic generator flows, please refer to the DPDK Test Report.
|
|
For more details on how to set up and run the sample applications provided with DPDK package,
|
|
please refer to the *DPDK Getting Started Guide*.
|
|
|
|
Explanation
|
|
-----------
|
|
|
|
Application Configuration
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
The application run-time configuration is done through the application command line parameters.
|
|
Any parameter that is not specified as mandatory is optional,
|
|
with the default value hard-coded in the main.h header file from the application folder.
|
|
|
|
The list of application command line parameters is listed below:
|
|
|
|
#. --rx "(PORT, QUEUE, LCORE), ...": The list of NIC RX ports and queues handled by the I/O RX lcores.
|
|
This parameter also implicitly defines the list of I/O RX lcores. This is a mandatory parameter.
|
|
|
|
#. --tx "(PORT, LCORE), ... ": The list of NIC TX ports handled by the I/O TX lcores.
|
|
This parameter also implicitly defines the list of I/O TX lcores.
|
|
This is a mandatory parameter.
|
|
|
|
#. --w "LCORE, ...": The list of the worker lcores. This is a mandatory parameter.
|
|
|
|
#. --lpm "IP / PREFIX => PORT; ...": The list of LPM rules used by the worker lcores for packet forwarding.
|
|
This is a mandatory parameter.
|
|
|
|
#. --rsz "A, B, C, D": Ring sizes:
|
|
|
|
#. A = The size (in number of buffer descriptors) of each of the NIC RX rings read by the I/O RX lcores.
|
|
|
|
#. B = The size (in number of elements) of each of the software rings used by the I/O RX lcores to send packets to worker lcores.
|
|
|
|
#. C = The size (in number of elements) of each of the software rings used by the worker lcores to send packets to I/O TX lcores.
|
|
|
|
#. D = The size (in number of buffer descriptors) of each of the NIC TX rings written by I/O TX lcores.
|
|
|
|
#. --bsz "(A, B), (C, D), (E, F)": Burst sizes:
|
|
|
|
#. A = The I/O RX lcore read burst size from NIC RX.
|
|
|
|
#. B = The I/O RX lcore write burst size to the output software rings.
|
|
|
|
#. C = The worker lcore read burst size from the input software rings.
|
|
|
|
#. D = The worker lcore write burst size to the output software rings.
|
|
|
|
#. E = The I/O TX lcore read burst size from the input software rings.
|
|
|
|
#. F = The I/O TX lcore write burst size to the NIC TX.
|
|
|
|
#. --pos-lb POS: The position of the 1-byte field within the input packet used by the I/O RX lcores
|
|
to identify the worker lcore for the current packet.
|
|
This field needs to be within the first 64 bytes of the input packet.
|
|
|
|
The infrastructure of software rings connecting I/O lcores and worker lcores is built by the application
|
|
as a result of the application configuration provided by the user through the application command line parameters.
|
|
|
|
A specific lcore performing the I/O RX role for a specific set of NIC ports can also perform the I/O TX role
|
|
for the same or a different set of NIC ports.
|
|
A specific lcore cannot perform both the I/O role (either RX or TX) and the worker role during the same session.
|
|
|
|
Example:
|
|
|
|
.. code-block:: console
|
|
|
|
./load_balancer -l 3-7 -n 4 -- --rx "(0,0,3),(1,0,3)" --tx "(0,3),(1,3)" --w "4,5,6,7" --lpm "1.0.0.0/24=>0; 1.0.1.0/24=>1;" --pos-lb 29
|
|
|
|
There is a single I/O lcore (lcore 3) that handles RX and TX for two NIC ports (ports 0 and 1) that
|
|
handles packets to/from four worker lcores (lcores 4, 5, 6 and 7) that
|
|
are assigned worker IDs 0 to 3 (worker ID for lcore 4 is 0, for lcore 5 is 1, for lcore 6 is 2 and for lcore 7 is 3).
|
|
|
|
Assuming that all the input packets are IPv4 packets with no VLAN label and the source IP address of the current packet is A.B.C.D,
|
|
the worker lcore for the current packet is determined by byte D (which is byte 29).
|
|
There are two LPM rules that are used by each worker lcore to route packets to the output NIC ports.
|
|
|
|
The following table illustrates the packet flow through the system for several possible traffic flows:
|
|
|
|
+------------+----------------+-----------------+------------------------------+--------------+
|
|
| **Flow #** | **Source** | **Destination** | **Worker ID (Worker lcore)** | **Output** |
|
|
| | **IP Address** | **IP Address** | | **NIC Port** |
|
|
| | | | | |
|
|
+============+================+=================+==============================+==============+
|
|
| 1 | 0.0.0.0 | 1.0.0.1 | 0 (4) | 0 |
|
|
| | | | | |
|
|
+------------+----------------+-----------------+------------------------------+--------------+
|
|
| 2 | 0.0.0.1 | 1.0.1.2 | 1 (5) | 1 |
|
|
| | | | | |
|
|
+------------+----------------+-----------------+------------------------------+--------------+
|
|
| 3 | 0.0.0.14 | 1.0.0.3 | 2 (6) | 0 |
|
|
| | | | | |
|
|
+------------+----------------+-----------------+------------------------------+--------------+
|
|
| 4 | 0.0.0.15 | 1.0.1.4 | 3 (7) | 1 |
|
|
| | | | | |
|
|
+------------+----------------+-----------------+------------------------------+--------------+
|
|
|
|
NUMA Support
|
|
~~~~~~~~~~~~
|
|
|
|
The application has built-in performance enhancements for the NUMA case:
|
|
|
|
#. One buffer pool per each CPU socket.
|
|
|
|
#. One LPM table per each CPU socket.
|
|
|
|
#. Memory for the NIC RX or TX rings is allocated on the same socket with the lcore handling the respective ring.
|
|
|
|
In the case where multiple CPU sockets are used in the system,
|
|
it is recommended to enable at least one lcore to fulfill the I/O role for the NIC ports that
|
|
are directly attached to that CPU socket through the PCI Express* bus.
|
|
It is always recommended to handle the packet I/O with lcores from the same CPU socket as the NICs.
|
|
|
|
Depending on whether the I/O RX lcore (same CPU socket as NIC RX),
|
|
the worker lcore and the I/O TX lcore (same CPU socket as NIC TX) handling a specific input packet,
|
|
are on the same or different CPU sockets, the following run-time scenarios are possible:
|
|
|
|
#. AAA: The packet is received, processed and transmitted without going across CPU sockets.
|
|
|
|
#. AAB: The packet is received and processed on socket A,
|
|
but as it has to be transmitted on a NIC port connected to socket B,
|
|
the packet is sent to socket B through software rings.
|
|
|
|
#. ABB: The packet is received on socket A, but as it has to be processed by a worker lcore on socket B,
|
|
the packet is sent to socket B through software rings.
|
|
The packet is transmitted by a NIC port connected to the same CPU socket as the worker lcore that processed it.
|
|
|
|
#. ABC: The packet is received on socket A, it is processed by an lcore on socket B,
|
|
then it has to be transmitted out by a NIC connected to socket C.
|
|
The performance price for crossing the CPU socket boundary is paid twice for this packet.
|