DPDK學習筆記<4>原始碼分析（1）

原始碼分析（1）helloworld

原始碼：

/*- *   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. */#include #include #include #include #include #include #include #include #include #include #include #include static intlcore_hello(__attribute__((unused)) void *arg){unsigned lcore_id;lcore_id = rte_lcore_id();printf("hello from core %u\n", lcore_id);return 0;}intmain(int argc, char **argv){int ret;unsigned lcore_id;ret = rte_eal_init(argc, argv);if (ret < 0)rte_panic("Cannot init EAL\n");/* call lcore_hello() on every slave lcore */RTE_LCORE_FOREACH_SLAVE(lcore_id) {rte_eal_remote_launch(lcore_hello, NULL, lcore_id);}/* call it on master lcore too */lcore_hello(NULL);rte_eal_mp_wait_lcore();return 0;}

分析：

helloworld為dpdk的入門範例程式，程式的編寫和系統編程一樣都是從main函數作為入口函數。

rte_eal_init()啟動基礎運行環境，該函數完成的工作比較複雜，讀取入口參數，解析並儲存DPDK啟動並執行系統資訊，並根據這些資訊構建包處理的運行環境。

配置初始化

記憶體初始化

記憶體池初始化

隊列初始化

警告初始化

中斷初始化

PCI初始化

定時器初始化

…………

使用DPDK這些操作已經被EAL封裝，如果需要進行深度定製二次開發，則需要進一步的研究。

RTE_LCORE_FOREACH_SLAVE(lcore_id) {rte_eal_remote_launch(lcore_hello, NULL, lcore_id);}

DPDK面向多核設計，程式試圖獨佔運行在邏輯核（lcore）上，RTE_LCORE_FOREACH_SLAVE遍曆EAL指定的可用邏輯核，然後在每個邏輯核上執行被指定的線程，本文中為

lcore_hello。（大家可以執行設計lcore_hello）。