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diff --git a/doc/guides/prog_guide/overview.rst b/doc/guides/prog_guide/overview.rst new file mode 100644 index 00000000..68cc75cc --- /dev/null +++ b/doc/guides/prog_guide/overview.rst @@ -0,0 +1,197 @@ +.. 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. + +**Part 1: Architecture Overview** + +Overview +======== + +This section gives a global overview of the architecture of Data Plane Development Kit (DPDK). + +The main goal of the DPDK is to provide a simple, +complete framework for fast packet processing in data plane applications. +Users may use the code to understand some of the techniques employed, +to build upon for prototyping or to add their own protocol stacks. +Alternative ecosystem options that use the DPDK are available. + +The framework creates a set of libraries for specific environments +through the creation of an Environment Abstraction Layer (EAL), +which may be specific to a mode of the Intel® architecture (32-bit or 64-bit), +Linux* user space compilers or a specific platform. +These environments are created through the use of make files and configuration files. +Once the EAL library is created, the user may link with the library to create their own applications. +Other libraries, outside of EAL, including the Hash, +Longest Prefix Match (LPM) and rings libraries are also provided. +Sample applications are provided to help show the user how to use various features of the DPDK. + +The DPDK implements a run to completion model for packet processing, +where all resources must be allocated prior to calling Data Plane applications, +running as execution units on logical processing cores. +The model does not support a scheduler and all devices are accessed by polling. +The primary reason for not using interrupts is the performance overhead imposed by interrupt processing. + +In addition to the run-to-completion model, +a pipeline model may also be used by passing packets or messages between cores via the rings. +This allows work to be performed in stages and may allow more efficient use of code on cores. + +Development Environment +----------------------- + +The DPDK project installation requires Linux and the associated toolchain, +such as one or more compilers, assembler, make utility, +editor and various libraries to create the DPDK components and libraries. + +Once these libraries are created for the specific environment and architecture, +they may then be used to create the user's data plane application. + +When creating applications for the Linux user space, the glibc library is used. +For DPDK applications, two environmental variables (RTE_SDK and RTE_TARGET) +must be configured before compiling the applications. +The following are examples of how the variables can be set: + +.. code-block:: console + + export RTE_SDK=/home/user/DPDK + export RTE_TARGET=x86_64-native-linuxapp-gcc + +See the *DPDK Getting Started Guide* for information on setting up the development environment. + +Environment Abstraction Layer +----------------------------- + +The Environment Abstraction Layer (EAL) provides a generic interface +that hides the environment specifics from the applications and libraries. +The services provided by the EAL are: + +* DPDK loading and launching + +* Support for multi-process and multi-thread execution types + +* Core affinity/assignment procedures + +* System memory allocation/de-allocation + +* Atomic/lock operations + +* Time reference + +* PCI bus access + +* Trace and debug functions + +* CPU feature identification + +* Interrupt handling + +* Alarm operations + +* Memory management (malloc) + +The EAL is fully described in :ref:`Environment Abstraction Layer <Environment_Abstraction_Layer>`. + +Core Components +--------------- + +The *core components* are a set of libraries that provide all the elements needed +for high-performance packet processing applications. + +.. _figure_architecture-overview: + +.. figure:: img/architecture-overview.* + + Core Components Architecture + + +Ring Manager (librte_ring) +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The ring structure provides a lockless multi-producer, multi-consumer FIFO API in a finite size table. +It has some advantages over lockless queues; easier to implement, adapted to bulk operations and faster. +A ring is used by the :ref:`Memory Pool Manager (librte_mempool) <Mempool_Library>` +and may be used as a general communication mechanism between cores +and/or execution blocks connected together on a logical core. + +This ring buffer and its usage are fully described in :ref:`Ring Library <Ring_Library>`. + +Memory Pool Manager (librte_mempool) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The Memory Pool Manager is responsible for allocating pools of objects in memory. +A pool is identified by name and uses a ring to store free objects. +It provides some other optional services, +such as a per-core object cache and an alignment helper to ensure that objects are padded to spread them equally on all RAM channels. + +This memory pool allocator is described in :ref:`Mempool Library <Mempool_Library>`. + +Network Packet Buffer Management (librte_mbuf) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The mbuf library provides the facility to create and destroy buffers +that may be used by the DPDK application to store message buffers. +The message buffers are created at startup time and stored in a mempool, using the DPDK mempool library. + +This library provide an API to allocate/free mbufs, manipulate control message buffers (ctrlmbuf) which are generic message buffers, +and packet buffers (pktmbuf) which are used to carry network packets. + +Network Packet Buffer Management is described in :ref:`Mbuf Library <Mbuf_Library>`. + +Timer Manager (librte_timer) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +This library provides a timer service to DPDK execution units, +providing the ability to execute a function asynchronously. +It can be periodic function calls, or just a one-shot call. +It uses the timer interface provided by the Environment Abstraction Layer (EAL) +to get a precise time reference and can be initiated on a per-core basis as required. + +The library documentation is available in :ref:`Timer Library <Timer_Library>`. + +Ethernet* Poll Mode Driver Architecture +--------------------------------------- + +The DPDK includes Poll Mode Drivers (PMDs) for 1 GbE, 10 GbE and 40GbE, and para virtualized virtio +Ethernet controllers which are designed to work without asynchronous, interrupt-based signaling mechanisms. + +See :ref:`Poll Mode Driver <Poll_Mode_Driver>`. + +Packet Forwarding Algorithm Support +----------------------------------- + +The DPDK includes Hash (librte_hash) and Longest Prefix Match (LPM,librte_lpm) +libraries to support the corresponding packet forwarding algorithms. + +See :ref:`Hash Library <Hash_Library>` and :ref:`LPM Library <LPM_Library>` for more information. + +librte_net +---------- + +The librte_net library is a collection of IP protocol definitions and convenience macros. +It is based on code from the FreeBSD* IP stack and contains protocol numbers (for use in IP headers), +IP-related macros, IPv4/IPv6 header structures and TCP, UDP and SCTP header structures. |