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31 **Part 1: Architecture Overview**
36 This section gives a global overview of the architecture of Data Plane Development Kit (DPDK).
38 The main goal of the DPDK is to provide a simple,
39 complete framework for fast packet processing in data plane applications.
40 Users may use the code to understand some of the techniques employed,
41 to build upon for prototyping or to add their own protocol stacks.
42 Alternative ecosystem options that use the DPDK are available.
44 The framework creates a set of libraries for specific environments
45 through the creation of an Environment Abstraction Layer (EAL),
46 which may be specific to a mode of the IntelĀ® architecture (32-bit or 64-bit),
47 Linux* user space compilers or a specific platform.
48 These environments are created through the use of make files and configuration files.
49 Once the EAL library is created, the user may link with the library to create their own applications.
50 Other libraries, outside of EAL, including the Hash,
51 Longest Prefix Match (LPM) and rings libraries are also provided.
52 Sample applications are provided to help show the user how to use various features of the DPDK.
54 The DPDK implements a run to completion model for packet processing,
55 where all resources must be allocated prior to calling Data Plane applications,
56 running as execution units on logical processing cores.
57 The model does not support a scheduler and all devices are accessed by polling.
58 The primary reason for not using interrupts is the performance overhead imposed by interrupt processing.
60 In addition to the run-to-completion model,
61 a pipeline model may also be used by passing packets or messages between cores via the rings.
62 This allows work to be performed in stages and may allow more efficient use of code on cores.
64 Development Environment
65 -----------------------
67 The DPDK project installation requires Linux and the associated toolchain,
68 such as one or more compilers, assembler, make utility,
69 editor and various libraries to create the DPDK components and libraries.
71 Once these libraries are created for the specific environment and architecture,
72 they may then be used to create the user's data plane application.
74 When creating applications for the Linux user space, the glibc library is used.
75 For DPDK applications, two environmental variables (RTE_SDK and RTE_TARGET)
76 must be configured before compiling the applications.
77 The following are examples of how the variables can be set:
79 .. code-block:: console
81 export RTE_SDK=/home/user/DPDK
82 export RTE_TARGET=x86_64-native-linuxapp-gcc
84 See the *DPDK Getting Started Guide* for information on setting up the development environment.
86 Environment Abstraction Layer
87 -----------------------------
89 The Environment Abstraction Layer (EAL) provides a generic interface
90 that hides the environment specifics from the applications and libraries.
91 The services provided by the EAL are:
93 * DPDK loading and launching
95 * Support for multi-process and multi-thread execution types
97 * Core affinity/assignment procedures
99 * System memory allocation/de-allocation
101 * Atomic/lock operations
107 * Trace and debug functions
109 * CPU feature identification
115 The EAL is fully described in :ref:`Environment Abstraction Layer <Environment_Abstraction_Layer>`.
120 The *core components* are a set of libraries that provide all the elements needed
121 for high-performance packet processing applications.
125 **Figure 1. Core Components Architecture**
127 .. image2_png has been replaced
129 |architecture-overview|
131 Memory Manager (librte_malloc)
132 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
134 The librte_malloc library provides an API to allocate memory from the memzones created from the hugepages instead of the heap.
135 This helps when allocating large numbers of items that may become susceptible to TLB misses
136 when using typical 4k heap pages in the Linux user space environment.
138 This memory allocator is fully described in :ref:`Malloc Library <Malloc_Library>`.
140 Ring Manager (librte_ring)
141 ~~~~~~~~~~~~~~~~~~~~~~~~~~
143 The ring structure provides a lockless multi-producer, multi-consumer FIFO API in a finite size table.
144 It has some advantages over lockless queues; easier to implement, adapted to bulk operations and faster.
145 A ring is used by the :ref:`Memory Pool Manager (librte_mempool) <Mempool_Library>`
146 and may be used as a general communication mechanism between cores
147 and/or execution blocks connected together on a logical core.
149 This ring buffer and its usage are fully described in :ref:`Ring Library <Ring_Library>`.
151 Memory Pool Manager (librte_mempool)
152 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
154 The Memory Pool Manager is responsible for allocating pools of objects in memory.
155 A pool is identified by name and uses a ring to store free objects.
156 It provides some other optional services,
157 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.
159 This memory pool allocator is described in :ref:`Mempool Library <Mempool_Library>`.
161 Network Packet Buffer Management (librte_mbuf)
162 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
164 The mbuf library provides the facility to create and destroy buffers
165 that may be used by the DPDK application to store message buffers.
166 The message buffers are created at startup time and stored in a mempool, using the DPDK mempool library.
168 This library provide an API to allocate/free mbufs, manipulate control message buffers (ctrlmbuf) which are generic message buffers,
169 and packet buffers (pktmbuf) which are used to carry network packets.
171 Network Packet Buffer Management is described in :ref:`Mbuf Library <Mbuf_Library>`.
173 Timer Manager (librte_timer)
174 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
176 This library provides a timer service to DPDK execution units,
177 providing the ability to execute a function asynchronously.
178 It can be periodic function calls, or just a one-shot call.
179 It uses the timer interface provided by the Environment Abstraction Layer (EAL)
180 to get a precise time reference and can be initiated on a per-core basis as required.
182 The library documentation is available in :ref:`Timer Library <Timer_Library>`.
184 Ethernet* Poll Mode Driver Architecture
185 ---------------------------------------
187 The DPDK includes Poll Mode Drivers (PMDs) for 1 GbE, 10 GbE and 40GbE, and para virtualized virtio
188 Ethernet controllers which are designed to work without asynchronous, interrupt-based signaling mechanisms.
190 See :ref:`Poll Mode Driver <Poll_Mode_Driver>`.
192 Packet Forwarding Algorithm Support
193 -----------------------------------
195 The DPDK includes Hash (librte_hash) and Longest Prefix Match (LPM,librte_lpm)
196 libraries to support the corresponding packet forwarding algorithms.
198 See :ref:`Hash Library <Hash_Library>` and :ref:`LPM Library <LPM_Library>` for more information.
203 The librte_net library is a collection of IP protocol definitions and convenience macros.
204 It is based on code from the FreeBSD* IP stack and contains protocol numbers (for use in IP headers),
205 IP-related macros, IPv4/IPv6 header structures and TCP, UDP and SCTP header structures.
207 .. |architecture-overview| image:: img/architecture-overview.svg