{"id":9156,"date":"2024-05-10T17:01:01","date_gmt":"2024-05-10T09:01:01","guid":{"rendered":""},"modified":"2024-05-10T17:01:01","modified_gmt":"2024-05-10T09:01:01","slug":"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse","status":"publish","type":"post","link":"https:\/\/mushiming.com\/9156.html","title":{"rendered":"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse"},"content":{"rendered":"<p><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"display: none;\"> \n <path stroke-linecap=\"round\" d=\"M5,0 0,2.5 5,5z\" id=\"raphael-marker-block\" style=\"-webkit-tap-highlight-color: rgba(0, 0, 0, 0);\"><\/path> \n<\/svg> <\/p>\n<p>\u6700\u8fd1\u5728\u5b66\u4e60 Intel \u7684 igb kernel driver \u7684 Rx page reuse \u90e8\u5206\uff0c\u5b66\u4e60\u7ed3\u675f\u4f5c\u4e00\u4e2a\u603b\u7ed3\u3002\u53ef\u80fd\u6587\u7ae0\u7684\u5185\u5bb9\u4f1a\u6709\u4e00\u4e9b\u4e0d\u51c6\u786e\u7684\u5730\u65b9\uff0c\u671b\u6307\u6b63\u3002<\/p>\n<p>page reuse \u5c31\u662f\u901a\u8fc7\u5728\u521d\u59cb\u7684\u65f6\u5019\u5206\u914d\uff08num_rx_desc - 1\uff09\u4e2a page\uff0c\u4e4b\u540e reuse\uff0c\u8fd9\u6837\u5c31\u4e0d\u7528\u50cf\u4ee5\u524d\u4e00\u6837\u4e00\u76f4 alloc skb\uff0c\u53ef\u4ee5\u5b9e\u73b0\u4f18\u5316\u3002\u5f53\u7136\uff0c\u5728 reuse fail \u7684\u65f6\u5019\uff0c\u8fd8\u662f\u9700\u8981\u91cd\u65b0 alloc \u7684\u3002\u8be5\u90e8\u5206\u4ee3\u7801\u5728igb_poll => igb_clean_rx_irq => igb_fetch_rx_buffer<\/p>\n<p>driver \u7684 tx \u548c rx \u5404\u81ea\u662f\u4e00\u4e2a ring\uff0c\u5305\u542b next_to_use \u548c next_to_clean\uff0c\u8fd9\u90e8\u5206\u5185\u5bb9\u53ef\u4ee5\u53c2\u8003\u8fd9\u7bc7\u6587\u7ae0\u5b66\u4e60\u4e00\u4e0b\u7f51\u5361\u9a71\u52a8\u6536\u53d1\u5305\u8fc7\u7a0b\uff0c\u6211\u540e\u9762\u7684\u753b\u56fe\u5206\u6790\u4e5f\u6709\u53c2\u8003\u5b83\u3002\u800c igb \u91cc\u9762\u4e3a\u4e86 page reuse \u53c8\u5f15\u5165\u4e86\u4e00\u4e2a next_to_alloc\u3002\u8fd9\u4e09\u4e2a\u53d8\u91cf\u9700\u8981\u6ce8\u610f\uff0c\u662f\u6838\u5fc3\u3002\u5982\u679c\u60f3\u8981\u5feb\u901f\u4e86\u89e3 page reuse\uff0c\u53ef\u4ee5\u76f4\u63a5\u4ece\u76ee\u5f55\u770b<strong>\u7ffb\u8f6c\u9875\u9762<\/strong>\u548c<strong>\u6d41\u7a0b\u56fe\u793a<\/strong>\u3002 <\/p>\n<div class=\"toc\">\n<h4>\u76ee\u5f55<\/h4>\n<ul>\n<li>\u4e00\u3001struct igb_rx_buffer<\/li>\n<li>\u4e8c\u3001igb_clean_rx_irq<\/li>\n<li>\u4e09\u3001igb_fetch_rx_buffer<\/li>\n<li>\u56db\u3001\u7ffb\u8f6c\u9875\u9762<\/li>\n<li>\u4e94\u3001\u6d41\u7a0b\u56fe\u793a<\/li>\n<li>\n<ul>\n<li>1. \u4e3a desc alloc buffer<\/li>\n<li>2. page reuse ok<\/li>\n<li>\n<ul>\n<li>2.1 \u4e00\u4e2a packet\uff0c\u4e00\u4e2a desc<\/li>\n<li>2.2 \u4e00\u4e2a packet\uff0c\u591a\u4e2a desc<\/li>\n<\/ul>\n<\/li>\n<li>3. page reuse fail<\/li>\n<li>\n<ul>\n<li>3.1 \u4e00\u4e2a packet\uff0c\u4e00\u4e2a desc<\/li>\n<li>3.2 \u4e00\u4e2a packet\uff0c\u591a\u4e2a desc<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li>\u516d\u3001\u603b\u7ed3\u8bed<\/li>\n<\/ul>\n<\/div>\n<h2>\u4e00\u3001struct igb_rx_buffer<\/h2>\n<p>\u9996\u5148\u770b\u4e00\u4e0b igb_rx_buffer\uff0c\u8fd9\u4e2a\u7ed3\u6784\u6bd4\u8f83\u7b80\u5355\uff0c\u4e3b\u8981\u662f dma\u3001page \u548c page_offset\u3002\u8fd9\u91cc\u9762\u6bd4\u8f83\u5173\u952e\u7684\u5c31\u662f page_offset\uff0c\u8fd9\u662f\u7528\u6765\u5b9a\u4f4d\u6240\u4f7f\u7528\u7684 buffer \u7684\u4f4d\u7f6e\u7684\uff0c\u540e\u7eed\u4e5f\u7528\u5f97\u5230\u3002\u8fd9\u91cc\u6709\u4e00\u4e2aCONFIG_IGB_DISABLE_PACKET_SPLIT\uff0c\u8fd9\u4e2a\u662f not defined \u7684\uff0c\u540e\u7eed\u4e5f\u6709\u6d89\u53ca\uff0c\u9700\u8981\u6ce8\u610f\u3002<\/p>\n<pre><code class=\"prism language-c\"><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_rx_buffer<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t<span class=\"token class-name\">dma_addr_t<\/span> dma<span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifdef<\/span> <span class=\"token expression\">CONFIG_IGB_DISABLE_PACKET_SPLIT<\/span><\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sk_buff<\/span> <span class=\"token operator\">*<\/span>skb<span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">else<\/span><\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">page<\/span> <span class=\"token operator\">*<\/span>page<span class=\"token punctuation\">;<\/span>\n\tu32 page_offset<span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n<span class=\"token punctuation\">}<\/span><span class=\"token punctuation\">;<\/span>\n<\/code><\/pre>\n<h2>\u4e8c\u3001igb_clean_rx_irq<\/h2>\n<p>\u8fd9\u4e2a\u51fd\u6570\u662f rx \u7684\u5904\u7406\u51fd\u6570\uff0c\u5373\u6536\u5305\u8fc7\u7a0b\uff0c\u53ea\u662f\u7b80\u5355\u7684\u63d0\u4e00\u4e0b\uff0c\u6bd5\u7adf\u4e0d\u662f\u672c\u6587\u7684\u91cd\u70b9\u3002<\/p>\n<pre><code class=\"prism language-c\"><span class=\"token comment\">\/* igb_clean_rx_irq -- * packet split *\/<\/span>\n<span class=\"token keyword\">static<\/span> bool <span class=\"token function\">igb_clean_rx_irq<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_q_vector<\/span> <span class=\"token operator\">*<\/span>q_vector<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">int<\/span> budget<span class=\"token punctuation\">)<\/span>\n<span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_ring<\/span> <span class=\"token operator\">*<\/span>rx_ring <span class=\"token operator\">=<\/span> q_vector<span class=\"token operator\">-><\/span>rx<span class=\"token punctuation\">.<\/span>ring<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sk_buff<\/span> <span class=\"token operator\">*<\/span>skb <span class=\"token operator\">=<\/span> rx_ring<span class=\"token operator\">-><\/span>skb<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token keyword\">unsigned<\/span> <span class=\"token keyword\">int<\/span> total_bytes <span class=\"token operator\">=<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> total_packets <span class=\"token operator\">=<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token comment\">\/\/igb_desc_unused return ((ntc > ntu) ? 0 : ring->count) + ntc - ntu - 1;<\/span>\n\t<span class=\"token comment\">\/\/\u8fd9\u91cc\u9762\u7684 ring->count \u5c31\u662f desc num\uff0ccleaned_count \u5c31\u662f hw \u6ca1\u6709\u4f7f\u7528\u3001\u9700\u8981 clean \u7684 desc \u6570\u76ee<\/span>\n\t<span class=\"token comment\">\/\/next_to_use \u7684 use \u662f\u6307\u6ca1\u6709\u586b\u5145\u8fc7\u6570\u636e\u5305\u5373\u5c06\u4f7f\u7528\u7684 desc\uff0c<\/span>\n\t<span class=\"token comment\">\/\/next_to_clean \u7684 clean\u662f\u6307\u5df2\u7ecf\u586b\u5145\u8fc7\u6570\u636e\u5305\uff0c\u5e76\u4e14\u5df2\u7ecf\u5c06\u6570\u636e\u9001\u5f80\u534f\u8bae\u6808\u540e\uff0c\u9700\u8981\u5904\u7406\u7684 desc<\/span>\n\tu16 cleaned_count <span class=\"token operator\">=<\/span> <span class=\"token function\">igb_desc_unused<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> \n\n\t<span class=\"token keyword\">do<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token keyword\">union<\/span> e1000_adv_rx_desc <span class=\"token operator\">*<\/span>rx_desc<span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* return some buffers to hardware, one at a time is too slow *\/<\/span>\n\t\t<span class=\"token comment\">\/\/\u5982\u679c\u9700\u8981 clean \u7684 desc \u8d85\u8fc7\u4e86\u9608\u503c\uff0c\u90a3\u4e48\u5148 clean \u4e00\u4e0b\uff0c\u8fd4\u8fd8\u4e00\u4e9b buffer \u7ed9 hw<\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>cleaned_count <span class=\"token operator\">>=<\/span> IGB_RX_BUFFER_WRITE<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t\t<span class=\"token function\">igb_alloc_rx_buffers<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> cleaned_count<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t\t\tcleaned_count <span class=\"token operator\">=<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token punctuation\">}<\/span>\n\n\t\t<span class=\"token comment\">\/\/\u8fd9\u91cc\u7ed9\u5230 next_to_clean<\/span>\n\t\trx_desc <span class=\"token operator\">=<\/span> <span class=\"token function\">IGB_RX_DESC<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> rx_ring<span class=\"token operator\">-><\/span>next_to_clean<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span><span class=\"token function\">igb_test_staterr<\/span><span class=\"token punctuation\">(<\/span>rx_desc<span class=\"token punctuation\">,<\/span> E1000_RXD_STAT_DD<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t\t<span class=\"token keyword\">break<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* * This memory barrier is needed to keep us from reading * any other fields out of the rx_desc until we know the * RXD_STAT_DD bit is set *\/<\/span>\n\t\t<span class=\"token function\">rmb<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* retrieve a buffer from the ring *\/<\/span>\n\t\t<span class=\"token comment\">\/\/\u628a\u8fd9\u4e2a next_to_clean \u6307\u5411\u7684 desc \u7ed9\u5230 igb_fetch_rx_buffer\uff0c\u7528\u4e8e reuse\uff0c\u4e5f\u5c31\u662f retrieve<\/span>\n\t\tskb <span class=\"token operator\">=<\/span> <span class=\"token function\">igb_fetch_rx_buffer<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> rx_desc<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* exit if we failed to retrieve a buffer *\/<\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>skb<span class=\"token punctuation\">)<\/span>\n\t\t\t<span class=\"token keyword\">break<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token comment\">\/\/\u6bcf\u7528\u5b8c\u4e00\u4e2a desc\uff0c\u8981 cleaned_count++\u3002<\/span>\n\t\tcleaned_count<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* fetch next buffer in frame if non-eop *\/<\/span>\n\t\t<span class=\"token comment\">\/\/\u8fd9\u91cc\u66f4\u65b0\u4e86 next_to_clean\uff0c\u5e76\u4e14\u5224\u65ad\u662f\u5426\u662f end of packet\uff0c\u5982\u679c\u662f\u7684\u8bdd\u5c31 return false\uff0c\u5426\u5219 return true\u3002<\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">igb_is_non_eop<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> rx_desc<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t\t<span class=\"token keyword\">continue<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* verify the packet layout is correct *\/<\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">igb_cleanup_headers<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> rx_desc<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t\tskb <span class=\"token operator\">=<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">;<\/span>\n\t\t\t<span class=\"token keyword\">continue<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token punctuation\">}<\/span>\n\n\t\t<span class=\"token comment\">\/* probably a little skewed due to removing CRC *\/<\/span>\n\t\ttotal_bytes <span class=\"token operator\">+=<\/span> skb<span class=\"token operator\">-><\/span>len<span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* populate checksum, timestamp, VLAN, and protocol *\/<\/span>\n\t\t<span class=\"token function\">igb_process_skb_fields<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> rx_desc<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifndef<\/span> <span class=\"token expression\">IGB_NO_LRO<\/span><\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">igb_can_lro<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> rx_desc<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t\t<span class=\"token function\">igb_lro_receive<\/span><span class=\"token punctuation\">(<\/span>q_vector<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token keyword\">else<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifdef<\/span> <span class=\"token expression\">HAVE_VLAN_RX_REGISTER<\/span><\/span>\n\t\t\t<span class=\"token function\">igb_receive_skb<\/span><span class=\"token punctuation\">(<\/span>q_vector<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">else<\/span><\/span>\n\t\t\t<span class=\"token function\">napi_gro_receive<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&<\/span>q_vector<span class=\"token operator\">-><\/span>napi<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifndef<\/span> <span class=\"token expression\">NETIF_F_GRO<\/span><\/span>\n\n\t\t<span class=\"token function\">netdev_ring<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">)<\/span><span class=\"token operator\">-><\/span>last_rx <span class=\"token operator\">=<\/span> jiffies<span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n\n\t\t<span class=\"token comment\">\/* reset skb pointer *\/<\/span>\n\t\tskb <span class=\"token operator\">=<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* update budget accounting *\/<\/span>\n\t\ttotal_packets<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span> <span class=\"token keyword\">while<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">likely<\/span><span class=\"token punctuation\">(<\/span>total_packets <span class=\"token operator\"><<\/span> budget<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* place incomplete frames back on ring for completion *\/<\/span>\n\trx_ring<span class=\"token operator\">-><\/span>skb <span class=\"token operator\">=<\/span> skb<span class=\"token punctuation\">;<\/span>\n\n\trx_ring<span class=\"token operator\">-><\/span>rx_stats<span class=\"token punctuation\">.<\/span>packets <span class=\"token operator\">+=<\/span> total_packets<span class=\"token punctuation\">;<\/span>\n\trx_ring<span class=\"token operator\">-><\/span>rx_stats<span class=\"token punctuation\">.<\/span>bytes <span class=\"token operator\">+=<\/span> total_bytes<span class=\"token punctuation\">;<\/span>\n\tq_vector<span class=\"token operator\">-><\/span>rx<span class=\"token punctuation\">.<\/span>total_packets <span class=\"token operator\">+=<\/span> total_packets<span class=\"token punctuation\">;<\/span>\n\tq_vector<span class=\"token operator\">-><\/span>rx<span class=\"token punctuation\">.<\/span>total_bytes <span class=\"token operator\">+=<\/span> total_bytes<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token comment\">\/\/\u8fd9\u91cc\u662f\u5728\u5faa\u73af\u7ed3\u675f\u540e\uff0c\u4e3a desc \u5206\u914d buffer<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>cleaned_count<span class=\"token punctuation\">)<\/span>\n\t\t<span class=\"token function\">igb_alloc_rx_buffers<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> cleaned_count<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifndef<\/span> <span class=\"token expression\">IGB_NO_LRO<\/span><\/span>\n\t<span class=\"token function\">igb_lro_flush_all<\/span><span class=\"token punctuation\">(<\/span>q_vector<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span> <span class=\"token comment\">\/* IGB_NO_LRO *\/<\/span><\/span>\n\t<span class=\"token keyword\">return<\/span> <span class=\"token punctuation\">(<\/span>total_packets <span class=\"token operator\"><<\/span> budget<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token punctuation\">}<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span> <span class=\"token comment\">\/* CONFIG_IGB_DISABLE_PACKET_SPLIT *\/<\/span><\/span>\n<\/code><\/pre>\n<pre><code class=\"prism language-c\"><span class=\"token comment\">\/** * igb_is_non_eop - process handling of non-EOP buffers * @rx_ring: Rx ring being processed * @rx_desc: Rx descriptor for current buffer * * This function updates next to clean. If the buffer is an EOP buffer * this function exits returning false, otherwise it will place the * sk_buff in the next buffer to be chained and return true indicating * that this is in fact a non-EOP buffer. * \u8fd9\u4e2a\u51fd\u6570\u66f4\u65b0 next to clean\u3002\u5982\u679c\u8fd9\u4e2a buffer \u662fEOP\uff08end of packet\uff09buffer \u90a3\u4e48\u51fd\u6570\u9000\u51fa\u5e76\u4e14 return false\u3002 * \u5426\u5219\uff0c\u5b83\u5c06\u628a sk_buff \u653e\u5728\u4e0b\u4e00\u4e2a\u8981\u94fe\u63a5\u7684\u7f13\u51b2\u533a\u4e2d\u5e76\u8fd4\u56de true\uff0c\u8868\u660e\u8fd9\u5b9e\u9645\u4e0a\u662f\u4e00\u4e2a\u975e EOP \u7f13\u51b2\u533a\u3002 **\/<\/span>\n<span class=\"token keyword\">static<\/span> bool <span class=\"token function\">igb_is_non_eop<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_ring<\/span> <span class=\"token operator\">*<\/span>rx_ring<span class=\"token punctuation\">,<\/span>\n\t\t\t <span class=\"token keyword\">union<\/span> e1000_adv_rx_desc <span class=\"token operator\">*<\/span>rx_desc<span class=\"token punctuation\">)<\/span>\n<span class=\"token punctuation\">{ \n <!-- --><\/span>\n\tu32 ntc <span class=\"token operator\">=<\/span> rx_ring<span class=\"token operator\">-><\/span>next_to_clean <span class=\"token operator\">+<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* fetch, update, and store next to clean *\/<\/span>\n\tntc <span class=\"token operator\">=<\/span> <span class=\"token punctuation\">(<\/span>ntc <span class=\"token operator\"><<\/span> rx_ring<span class=\"token operator\">-><\/span>count<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">?<\/span> ntc <span class=\"token operator\">:<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span>\n\trx_ring<span class=\"token operator\">-><\/span>next_to_clean <span class=\"token operator\">=<\/span> ntc<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token function\">prefetch<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">IGB_RX_DESC<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> ntc<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">likely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">igb_test_staterr<\/span><span class=\"token punctuation\">(<\/span>rx_desc<span class=\"token punctuation\">,<\/span> E1000_RXD_STAT_EOP<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t<span class=\"token keyword\">return<\/span> false<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token keyword\">return<\/span> true<span class=\"token punctuation\">;<\/span>\n<span class=\"token punctuation\">}<\/span>\n<\/code><\/pre>\n<pre><code class=\"prism language-c\"><span class=\"token comment\">\/** * igb_alloc_rx_buffers - Replace used receive buffers; packet split * @rx_ring: rx descriptor ring * @cleaned_count: number of buffers to clean **\/<\/span>\n<span class=\"token keyword\">void<\/span> <span class=\"token function\">igb_alloc_rx_buffers<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_ring<\/span> <span class=\"token operator\">*<\/span>rx_ring<span class=\"token punctuation\">,<\/span> u16 cleaned_count<span class=\"token punctuation\">)<\/span>\n<span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t<span class=\"token keyword\">union<\/span> e1000_adv_rx_desc <span class=\"token operator\">*<\/span>rx_desc<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_rx_buffer<\/span> <span class=\"token operator\">*<\/span>bi<span class=\"token punctuation\">;<\/span>\n\tu16 i <span class=\"token operator\">=<\/span> rx_ring<span class=\"token operator\">-><\/span>next_to_use<span class=\"token punctuation\">;<\/span><span class=\"token comment\">\/\/\u65e2\u7136\u662f\u5206\u914d buffer\uff0c\u90a3\u4e48\u5f97\u4ece next_to_use \u5f00\u59cb<\/span>\n\n\t<span class=\"token comment\">\/* nothing to do *\/<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>cleaned_count<span class=\"token punctuation\">)<\/span>\n\t\t<span class=\"token keyword\">return<\/span><span class=\"token punctuation\">;<\/span>\n\n\trx_desc <span class=\"token operator\">=<\/span> <span class=\"token function\">IGB_RX_DESC<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> i<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\tbi <span class=\"token operator\">=<\/span> <span class=\"token operator\">&<\/span>rx_ring<span class=\"token operator\">-><\/span>rx_buffer_info<span class=\"token punctuation\">[<\/span>i<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span>\n\ti <span class=\"token operator\">-=<\/span> rx_ring<span class=\"token operator\">-><\/span>count<span class=\"token punctuation\">;<\/span><span class=\"token comment\">\/\/\u5148\u51cf\u6389 num_rx_desc<\/span>\n\n\t<span class=\"token keyword\">do<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifdef<\/span> <span class=\"token expression\">CONFIG_IGB_DISABLE_PACKET_SPLIT<\/span><\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span><span class=\"token function\">igb_alloc_mapped_skb<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> bi<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">else<\/span><\/span>\n <span class=\"token comment\">\/\/\u5206\u914d page<\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span><span class=\"token function\">igb_alloc_mapped_page<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> bi<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span> <span class=\"token comment\">\/* CONFIG_IGB_DISABLE_PACKET_SPLIT *\/<\/span><\/span>\n\t\t\t<span class=\"token keyword\">break<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* * Refresh the desc even if buffer_addrs didn't change * because each write-back erases this info. *\/<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifdef<\/span> <span class=\"token expression\">CONFIG_IGB_DISABLE_PACKET_SPLIT<\/span><\/span>\n\t\trx_desc<span class=\"token operator\">-><\/span>read<span class=\"token punctuation\">.<\/span>pkt_addr <span class=\"token operator\">=<\/span> <span class=\"token function\">cpu_to_le64<\/span><span class=\"token punctuation\">(<\/span>bi<span class=\"token operator\">-><\/span>dma<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">else<\/span><\/span>\n\t\trx_desc<span class=\"token operator\">-><\/span>read<span class=\"token punctuation\">.<\/span>pkt_addr <span class=\"token operator\">=<\/span> <span class=\"token function\">cpu_to_le64<\/span><span class=\"token punctuation\">(<\/span>bi<span class=\"token operator\">-><\/span>dma <span class=\"token operator\">+<\/span> bi<span class=\"token operator\">-><\/span>page_offset<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n\n\t\trx_desc<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\t\tbi<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\t\ti<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token comment\">\/\/\u8fd9\u91cc\u7684\u76ee\u7684\u5c31\u662f\u4e3a\u4e86\u4f7f\u5f97 i \u7684\u503c\u5728 0 ~ 255 \u7684\u8303\u56f4\u5185<\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">unlikely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>i<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t\trx_desc <span class=\"token operator\">=<\/span> <span class=\"token function\">IGB_RX_DESC<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t\t\tbi <span class=\"token operator\">=<\/span> rx_ring<span class=\"token operator\">-><\/span>rx_buffer_info<span class=\"token punctuation\">;<\/span>\n\t\t\ti <span class=\"token operator\">-=<\/span> rx_ring<span class=\"token operator\">-><\/span>count<span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token punctuation\">}<\/span>\n\n\t\t<span class=\"token comment\">\/* clear the hdr_addr for the next_to_use descriptor *\/<\/span>\n\t\trx_desc<span class=\"token operator\">-><\/span>read<span class=\"token punctuation\">.<\/span>hdr_addr <span class=\"token operator\">=<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\tcleaned_count<span class=\"token operator\">--<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span> <span class=\"token keyword\">while<\/span> <span class=\"token punctuation\">(<\/span>cleaned_count<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\ti <span class=\"token operator\">+=<\/span> rx_ring<span class=\"token operator\">-><\/span>count<span class=\"token punctuation\">;<\/span><span class=\"token comment\">\/\/\u8fd9\u91cc\u518d\u52a0\u56de num_rx_desc<\/span>\n\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token operator\">-><\/span>next_to_use <span class=\"token operator\">!=<\/span> i<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token comment\">\/* record the next descriptor to use *\/<\/span>\n\t\trx_ring<span class=\"token operator\">-><\/span>next_to_use <span class=\"token operator\">=<\/span> i<span class=\"token punctuation\">;<\/span><span class=\"token comment\">\/\/\u66f4\u65b0 next_to_use<\/span>\n\n<span class=\"token comment\">\/\/\u8fd9\u91cc\u662f ifndef\uff0c\u96be\u602a\u7406\u4e86\u534a\u5929\u4e0d\u5bf9 = =<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifndef<\/span> <span class=\"token expression\">CONFIG_IGB_DISABLE_PACKET_SPLIT<\/span><\/span>\n\t\t<span class=\"token comment\">\/* update next to alloc since we have filled the ring *\/<\/span>\n\t\t<span class=\"token comment\">\/\/\u53ea\u8981\u8c03\u7528\u4e86alloc rx buffer\uff0c\u90a3\u4e48next_to_use = next_to_alloc<\/span>\n\t\trx_ring<span class=\"token operator\">-><\/span>next_to_alloc <span class=\"token operator\">=<\/span> i<span class=\"token punctuation\">;<\/span>\n\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n\t\t<span class=\"token comment\">\/* * Force memory writes to complete before letting h\/w * know there are new descriptors to fetch. (Only * applicable for weak-ordered memory model archs, * such as IA-64). *\/<\/span>\n\t\t<span class=\"token function\">wmb<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token function\">writel<\/span><span class=\"token punctuation\">(<\/span>i<span class=\"token punctuation\">,<\/span> rx_ring<span class=\"token operator\">-><\/span>tail<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span>\n<span class=\"token punctuation\">}<\/span>\n<\/code><\/pre>\n<pre><code class=\"prism language-c\"><span class=\"token keyword\">static<\/span> bool <span class=\"token function\">igb_alloc_mapped_page<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_ring<\/span> <span class=\"token operator\">*<\/span>rx_ring<span class=\"token punctuation\">,<\/span>\n\t\t\t\t <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_rx_buffer<\/span> <span class=\"token operator\">*<\/span>bi<span class=\"token punctuation\">)<\/span>\n<span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">page<\/span> <span class=\"token operator\">*<\/span>page <span class=\"token operator\">=<\/span> bi<span class=\"token operator\">-><\/span>page<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token class-name\">dma_addr_t<\/span> dma<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* since we are recycling buffers we should seldom need to alloc *\/<\/span>\n\t<span class=\"token comment\">\/\/\u5982\u679c reuse \u6210\u529f\uff0c\u90a3\u4e48\u5c31\u76f4\u63a5\u8df3\u51fa\u4e86<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">likely<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t<span class=\"token keyword\">return<\/span> true<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* alloc new page for storage *\/<\/span>\n\tpage <span class=\"token operator\">=<\/span> <span class=\"token function\">alloc_page<\/span><span class=\"token punctuation\">(<\/span>GFP_ATOMIC <span class=\"token operator\">|<\/span> __GFP_COLD<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">unlikely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>page<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\trx_ring<span class=\"token operator\">-><\/span>rx_stats<span class=\"token punctuation\">.<\/span>alloc_failed<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token keyword\">return<\/span> false<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span>\n\n\t<span class=\"token comment\">\/* map page for use *\/<\/span>\n\tdma <span class=\"token operator\">=<\/span> <span class=\"token function\">dma_map_page<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token operator\">-><\/span>dev<span class=\"token punctuation\">,<\/span> page<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> PAGE_SIZE<span class=\"token punctuation\">,<\/span> DMA_FROM_DEVICE<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* * if mapping failed free memory back to system since * there isn't much point in holding memory we can't use *\/<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">dma_mapping_error<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token operator\">-><\/span>dev<span class=\"token punctuation\">,<\/span> dma<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token function\">__free_page<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\trx_ring<span class=\"token operator\">-><\/span>rx_stats<span class=\"token punctuation\">.<\/span>alloc_failed<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token keyword\">return<\/span> false<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span>\n\n\tbi<span class=\"token operator\">-><\/span>dma <span class=\"token operator\">=<\/span> dma<span class=\"token punctuation\">;<\/span>\n\tbi<span class=\"token operator\">-><\/span>page <span class=\"token operator\">=<\/span> page<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token comment\">\/\/\u521d\u59cb\u7684 offset \u4e3a 0<\/span>\n\tbi<span class=\"token operator\">-><\/span>page_offset <span class=\"token operator\">=<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token keyword\">return<\/span> true<span class=\"token punctuation\">;<\/span>\n<span class=\"token punctuation\">}<\/span>\n<\/code><\/pre>\n<h2>\u4e09\u3001igb_fetch_rx_buffer<\/h2>\n<p>\u63a5\u4e0b\u6765\u5c31\u770b igb_fetch_rx_buffer \u4e86\uff0ccode \u90e8\u5206\u5176\u5b9e Intel \u7684\u6ce8\u91ca\u633a\u5168\u9762\u7684\u3002<\/p>\n<pre><code class=\"prism language-c\"><span class=\"token keyword\">static<\/span> <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sk_buff<\/span> <span class=\"token operator\">*<\/span><span class=\"token function\">igb_fetch_rx_buffer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_ring<\/span> <span class=\"token operator\">*<\/span>rx_ring<span class=\"token punctuation\">,<\/span>\n\t\t\t\t\t <span class=\"token keyword\">union<\/span> e1000_adv_rx_desc <span class=\"token operator\">*<\/span>rx_desc<span class=\"token punctuation\">,<\/span>\n\t\t\t\t\t <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sk_buff<\/span> <span class=\"token operator\">*<\/span>skb<span class=\"token punctuation\">)<\/span>\n<span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_rx_buffer<\/span> <span class=\"token operator\">*<\/span>rx_buffer<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">page<\/span> <span class=\"token operator\">*<\/span>page<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/\/\u56e0\u4e3a\u8981\u56de\u6536 rx_buffer\uff0crx_buffer \u6307\u5411 next_to_clean<\/span>\n\trx_buffer <span class=\"token operator\">=<\/span> <span class=\"token operator\">&<\/span>rx_ring<span class=\"token operator\">-><\/span>rx_buffer_info<span class=\"token punctuation\">[<\/span>rx_ring<span class=\"token operator\">-><\/span>next_to_clean<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span>\n\n\tpage <span class=\"token operator\">=<\/span> rx_buffer<span class=\"token operator\">-><\/span>page<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token function\">prefetchw<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><span class=\"token comment\">\/\/__builtin_prefetch() \u662f gcc \u7684\u4e00\u4e2a\u5185\u7f6e\u51fd\u6570\u3002\u5b83\u901a\u8fc7\u5bf9\u6570\u636e\u624b\u5de5\u9884\u53d6\u7684\u65b9\u6cd5\uff0c\u51cf\u5c11\u4e86\u8bfb\u53d6\u5ef6\u8fdf\uff0c\u4ece\u800c\u63d0\u9ad8\u4e86\u6027\u80fd\uff0c\u4f46\u8be5\u51fd\u6570\u4e5f\u9700\u8981 CPU \u7684\u652f\u6301\u3002<\/span>\n\n\t<span class=\"token comment\">\/\/\u770b\u770b\u8fd9\u4e2a ring \u7684 skb \u662f\u5426\u4e3a\u7a7a\uff0c\u5982\u679c\u4e3a\u7a7a\uff0c\u90a3\u4e48\u91cd\u65b0\u5206\u914d\u4e00\u4e2a skb \u7ed9\u5b83<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">likely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token keyword\">void<\/span> <span class=\"token operator\">*<\/span>page_addr <span class=\"token operator\">=<\/span> <span class=\"token function\">page_address<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">+<\/span>\n\t\t\t\t rx_buffer<span class=\"token operator\">-><\/span>page_offset<span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* prefetch first cache line of first page *\/<\/span>\n\t\t<span class=\"token function\">prefetch<\/span><span class=\"token punctuation\">(<\/span>page_addr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">if<\/span> <span class=\"token expression\">L1_CACHE_BYTES <span class=\"token operator\"><<\/span> <span class=\"token number\">128<\/span><\/span><\/span>\n\t\t<span class=\"token function\">prefetch<\/span><span class=\"token punctuation\">(<\/span>page_addr <span class=\"token operator\">+<\/span> L1_CACHE_BYTES<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n\n\t\t<span class=\"token comment\">\/* allocate a skb to store the frags *\/<\/span>\n\t\tskb <span class=\"token operator\">=<\/span> <span class=\"token function\">netdev_alloc_skb_ip_align<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token operator\">-><\/span>netdev<span class=\"token punctuation\">,<\/span>\n\t\t\t\t\t\tIGB_RX_HDR_LEN<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">unlikely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t\trx_ring<span class=\"token operator\">-><\/span>rx_stats<span class=\"token punctuation\">.<\/span>alloc_failed<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\t\t\t<span class=\"token keyword\">return<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token punctuation\">}<\/span>\n\n\t\t<span class=\"token comment\">\/* * we will be copying header into skb->data in * pskb_may_pull so it is in our interest to prefetch * it now to avoid a possible cache miss *\/<\/span>\n\t\t<span class=\"token function\">prefetchw<\/span><span class=\"token punctuation\">(<\/span>skb<span class=\"token operator\">-><\/span>data<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span>\n\n\t<span class=\"token comment\">\/* we are reusing so sync this buffer for CPU use *\/<\/span>\n\t<span class=\"token function\">dma_sync_single_range_for_cpu<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token operator\">-><\/span>dev<span class=\"token punctuation\">,<\/span>\n\t\t\t\t rx_buffer<span class=\"token operator\">-><\/span>dma<span class=\"token punctuation\">,<\/span>\n\t\t\t\t rx_buffer<span class=\"token operator\">-><\/span>page_offset<span class=\"token punctuation\">,<\/span>\n\t\t\t\t IGB_RX_BUFSZ<span class=\"token punctuation\">,<\/span>\n\t\t\t\t DMA_FROM_DEVICE<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* pull page into skb *\/<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">igb_add_rx_frag<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> rx_buffer<span class=\"token punctuation\">,<\/span> rx_desc<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token comment\">\/* hand second half of page back to the ring *\/<\/span>\n\t\t<span class=\"token function\">igb_reuse_rx_page<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token punctuation\">,<\/span> rx_buffer<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span> <span class=\"token keyword\">else<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token comment\">\/* we are not reusing the buffer so unmap it *\/<\/span>\n\t\t<span class=\"token function\">dma_unmap_page<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token operator\">-><\/span>dev<span class=\"token punctuation\">,<\/span> rx_buffer<span class=\"token operator\">-><\/span>dma<span class=\"token punctuation\">,<\/span>\n\t\t\t PAGE_SIZE<span class=\"token punctuation\">,<\/span> DMA_FROM_DEVICE<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span>\n\n\t<span class=\"token comment\">\/* clear contents of rx_buffer *\/<\/span>\n\t<span class=\"token comment\">\/\/\u56e0\u4e3a\u6570\u636e\u5df2\u7ecf\u590d\u5236\u5230 skb \u91cc\u4e86\uff0c\u6240\u4ee5\u8fd9\u91cc\u628a page \u7ed9\u6e05\u7a7a\u4e86<\/span>\n\trx_buffer<span class=\"token operator\">-><\/span>page <span class=\"token operator\">=<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token keyword\">return<\/span> skb<span class=\"token punctuation\">;<\/span>\n<span class=\"token punctuation\">}<\/span>\n<\/code><\/pre>\n<p>\u63a5\u4e0b\u6765\u770b igb_add_rx_frag\u3002<\/p>\n<pre><code class=\"prism language-c\"><span class=\"token comment\">\/** * igb_add_rx_frag - Add contents of Rx buffer to sk_buff * @rx_ring: rx descriptor ring to transact packets on * @rx_buffer: buffer containing page to add * @rx_desc: descriptor containing length of buffer written by hardware * @skb: sk_buff to place the data into * * This function will add the data contained in rx_buffer->page to the skb. * This is done either through a direct copy if the data in the buffer is * less than the skb header size, otherwise it will just attach the page as * a frag to the skb. * \u6b64\u51fd\u6570\u4f1a\u5c06 rx_buffer->page \u4e2d\u5305\u542b\u7684\u6570\u636e\u6dfb\u52a0\u5230 skb\u3002 * \u5982\u679c\u7f13\u51b2\u533a\u4e2d\u7684\u6570\u636e\u5c0f\u4e8e skb \u6807\u5934\u5927\u5c0f\uff0c\u5219\u53ef\u4ee5\u901a\u8fc7\u76f4\u63a5\u590d\u5236\u6765\u5b8c\u6210\u6b64\u64cd\u4f5c\uff0c\u5426\u5219\u5b83\u5c06\u4ec5\u5c06\u9875\u9762\u4f5c\u4e3a\u788e\u7247\u9644\u52a0\u5230 skb\u3002 * * The function will then update the page offset if necessary and return * true if the buffer can be reused by the adapter. * \u5982\u679c\u9700\u8981\uff0c\u8be5\u51fd\u6570\u5c06\u66f4\u65b0\u9875\u9762\u504f\u79fb\u91cf\u3002\u5982\u679c adapter \u53ef\u4ee5\u91cd\u7528 buffer\uff0c\u5219\u8fd4\u56de true\u3002 **\/<\/span>\n<span class=\"token keyword\">static<\/span> bool <span class=\"token function\">igb_add_rx_frag<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_ring<\/span> <span class=\"token operator\">*<\/span>rx_ring<span class=\"token punctuation\">,<\/span>\n\t\t\t <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_rx_buffer<\/span> <span class=\"token operator\">*<\/span>rx_buffer<span class=\"token punctuation\">,<\/span>\n\t\t\t <span class=\"token keyword\">union<\/span> e1000_adv_rx_desc <span class=\"token operator\">*<\/span>rx_desc<span class=\"token punctuation\">,<\/span>\n\t\t\t <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sk_buff<\/span> <span class=\"token operator\">*<\/span>skb<span class=\"token punctuation\">)<\/span>\n<span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">page<\/span> <span class=\"token operator\">*<\/span>page <span class=\"token operator\">=<\/span> rx_buffer<span class=\"token operator\">-><\/span>page<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token keyword\">unsigned<\/span> <span class=\"token keyword\">char<\/span> <span class=\"token operator\">*<\/span>va <span class=\"token operator\">=<\/span> <span class=\"token function\">page_address<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">+<\/span> rx_buffer<span class=\"token operator\">-><\/span>page_offset<span class=\"token punctuation\">;<\/span><span class=\"token comment\">\/\/virtual address<\/span>\n\t<span class=\"token keyword\">unsigned<\/span> <span class=\"token keyword\">int<\/span> size <span class=\"token operator\">=<\/span> <span class=\"token function\">le16_to_cpu<\/span><span class=\"token punctuation\">(<\/span>rx_desc<span class=\"token operator\">-><\/span>wb<span class=\"token punctuation\">.<\/span>upper<span class=\"token punctuation\">.<\/span>length<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">if<\/span> <span class=\"token expression\"><span class=\"token punctuation\">(<\/span>PAGE_SIZE <span class=\"token operator\"><<\/span> <span class=\"token number\">8192<\/span><span class=\"token punctuation\">)<\/span><\/span><span class=\"token comment\">\/\/\u6211\u6240\u4f7f\u7528\u7684 kernel \u4e2d page size \u662f 4096<\/span><\/span>\n\t<span class=\"token keyword\">unsigned<\/span> <span class=\"token keyword\">int<\/span> truesize <span class=\"token operator\">=<\/span> IGB_RX_BUFSZ<span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">else<\/span><\/span>\n\t<span class=\"token keyword\">unsigned<\/span> <span class=\"token keyword\">int<\/span> truesize <span class=\"token operator\">=<\/span> <span class=\"token function\">SKB_DATA_ALIGN<\/span><span class=\"token punctuation\">(<\/span>size<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n\t<span class=\"token keyword\">unsigned<\/span> <span class=\"token keyword\">int<\/span> pull_len<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">unlikely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">skb_is_nonlinear<\/span><span class=\"token punctuation\">(<\/span>skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t<span class=\"token keyword\">goto<\/span> add_tail_frag<span class=\"token punctuation\">;<\/span>\n\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">ifdef<\/span> <span class=\"token expression\">HAVE_PTP_1588_CLOCK<\/span><\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">unlikely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">igb_test_staterr<\/span><span class=\"token punctuation\">(<\/span>rx_desc<span class=\"token punctuation\">,<\/span> E1000_RXDADV_STAT_TSIP<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token function\">igb_ptp_rx_pktstamp<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token operator\">-><\/span>q_vector<span class=\"token punctuation\">,<\/span> va<span class=\"token punctuation\">,<\/span> skb<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t\tva <span class=\"token operator\">+=<\/span> IGB_TS_HDR_LEN<span class=\"token punctuation\">;<\/span>\n\t\tsize <span class=\"token operator\">-=<\/span> IGB_TS_HDR_LEN<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span> <span class=\"token comment\">\/* HAVE_PTP_1588_CLOCK *\/<\/span><\/span>\n\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">likely<\/span><span class=\"token punctuation\">(<\/span>size <span class=\"token operator\"><=<\/span> IGB_RX_HDR_LEN<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token function\">memcpy<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">__skb_put<\/span><span class=\"token punctuation\">(<\/span>skb<span class=\"token punctuation\">,<\/span> size<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> va<span class=\"token punctuation\">,<\/span> <span class=\"token function\">ALIGN<\/span><span class=\"token punctuation\">(<\/span>size<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">long<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* we can reuse buffer as-is, just make sure it is local *\/<\/span>\n\t\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">likely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">page_to_nid<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">==<\/span> <span class=\"token function\">numa_node_id<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t\t<span class=\"token keyword\">return<\/span> true<span class=\"token punctuation\">;<\/span>\n\n\t\t<span class=\"token comment\">\/* this page cannot be reused so discard it *\/<\/span>\n\t\t<span class=\"token function\">put_page<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token keyword\">return<\/span> false<span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span>\n\n\t<span class=\"token comment\">\/* we need the header to contain the greater of either ETH_HLEN or * 60 bytes if the skb->len is less than 60 for skb_pad. *\/<\/span>\n\tpull_len <span class=\"token operator\">=<\/span> <span class=\"token function\">eth_get_headlen<\/span><span class=\"token punctuation\">(<\/span>skb<span class=\"token operator\">-><\/span>dev<span class=\"token punctuation\">,<\/span> va<span class=\"token punctuation\">,<\/span> IGB_RX_HDR_LEN<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* align pull length to size of long to optimize memcpy performance *\/<\/span>\n\t<span class=\"token function\">memcpy<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">__skb_put<\/span><span class=\"token punctuation\">(<\/span>skb<span class=\"token punctuation\">,<\/span> pull_len<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> va<span class=\"token punctuation\">,<\/span> <span class=\"token function\">ALIGN<\/span><span class=\"token punctuation\">(<\/span>pull_len<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">long<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* update all of the pointers *\/<\/span>\n\tva <span class=\"token operator\">+=<\/span> pull_len<span class=\"token punctuation\">;<\/span>\n\tsize <span class=\"token operator\">-=<\/span> pull_len<span class=\"token punctuation\">;<\/span>\n\nadd_tail_frag<span class=\"token operator\">:<\/span>\n\t<span class=\"token function\">skb_add_rx_frag<\/span><span class=\"token punctuation\">(<\/span>skb<span class=\"token punctuation\">,<\/span> <span class=\"token function\">skb_shinfo<\/span><span class=\"token punctuation\">(<\/span>skb<span class=\"token punctuation\">)<\/span><span class=\"token operator\">-><\/span>nr_frags<span class=\"token punctuation\">,<\/span> page<span class=\"token punctuation\">,<\/span>\n\t\t\t<span class=\"token punctuation\">(<\/span><span class=\"token keyword\">unsigned<\/span> <span class=\"token keyword\">long<\/span><span class=\"token punctuation\">)<\/span>va <span class=\"token operator\">&<\/span> <span class=\"token operator\">~<\/span>PAGE_MASK<span class=\"token punctuation\">,<\/span> size<span class=\"token punctuation\">,<\/span> truesize<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token keyword\">return<\/span> <span class=\"token function\">igb_can_reuse_rx_page<\/span><span class=\"token punctuation\">(<\/span>rx_buffer<span class=\"token punctuation\">,<\/span> page<span class=\"token punctuation\">,<\/span> truesize<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token punctuation\">}<\/span>\n<\/code><\/pre>\n<p>igb_can_reuse_rx_page \u5224\u65ad\u662f\u5426\u53ef\u4ee5 reuse \u7684\uff0c\u4ee5\u53ca\u5b9e\u73b0\u7ffb\u8f6c\u3002<\/p>\n<pre><code class=\"prism language-c\"><span class=\"token keyword\">static<\/span> bool <span class=\"token function\">igb_can_reuse_rx_page<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_rx_buffer<\/span> <span class=\"token operator\">*<\/span>rx_buffer<span class=\"token punctuation\">,<\/span>\n\t\t\t\t <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">page<\/span> <span class=\"token operator\">*<\/span>page<span class=\"token punctuation\">,<\/span>\n\t\t\t\t <span class=\"token keyword\">unsigned<\/span> <span class=\"token keyword\">int<\/span> truesize<span class=\"token punctuation\">)<\/span>\n<span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t<span class=\"token comment\">\/* avoid re-using remote pages *\/<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">unlikely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">page_to_nid<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">!=<\/span> <span class=\"token function\">numa_node_id<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t<span class=\"token keyword\">return<\/span> false<span class=\"token punctuation\">;<\/span>\n\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">if<\/span> <span class=\"token expression\"><span class=\"token punctuation\">(<\/span>PAGE_SIZE <span class=\"token operator\"><<\/span> <span class=\"token number\">8192<\/span><span class=\"token punctuation\">)<\/span><\/span><\/span>\n\t<span class=\"token comment\">\/* if we are only owner of page we can reuse it *\/<\/span>\n\t<span class=\"token comment\">\/\/page \u521a\u5206\u914d\u7684\u65f6\u5019 page count \u662f 1\uff0c\u5982\u679c\u65e2\u88ab cpu \u4f7f\u7528\uff0c\u53c8\u88ab nic \u4f7f\u7528\uff0cpage count \u662f 2\u3002\u6240\u4ee5\u8fd9\u91cc\u5224\u65ad\u662f\u5426\u4e3a 1<\/span>\n\t<span class=\"token comment\">\/\/\u53ea\u6709\u8fd9\u4e2a page \u5df2\u7ecf\u4e0d\u88ab nic \u4f7f\u7528\uff0c\u624d\u53ef\u4ee5 reuse<\/span>\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">unlikely<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">page_count<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">!=<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t<span class=\"token keyword\">return<\/span> false<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* flip page offset to other buffer *\/<\/span>\n\t<span class=\"token comment\">\/\/\u5c06\u9875\u9762\u504f\u79fb\u91cf\u7ffb\u8f6c\u5230\u5176\u4ed6\u7f13\u51b2\u533a\uff0c\u8fd9\u90e8\u5206\u662f\u6211\u4e00\u5f00\u59cb\u6bd4\u8f83\u4e0d\u660e\u767d\u7684\u4e00\u70b9\uff0c\u540e\u7eed\u6211\u4f1a\u901a\u8fc7\u753b\u56fe\u6765\u89e3\u91ca\u4e00\u4e0b\u3002<\/span>\n\t<span class=\"token comment\">\/\/\u8fd9\u91cc\u7684 IGB_RX_BUFSZ = 2048<\/span>\n\trx_buffer<span class=\"token operator\">-><\/span>page_offset <span class=\"token operator\">^=<\/span> IGB_RX_BUFSZ<span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">else<\/span><\/span>\n\t<span class=\"token comment\">\/* move offset up to the next cache line *\/<\/span>\n\trx_buffer<span class=\"token operator\">-><\/span>page_offset <span class=\"token operator\">+=<\/span> truesize<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>rx_buffer<span class=\"token operator\">-><\/span>page_offset <span class=\"token operator\">><\/span> <span class=\"token punctuation\">(<\/span>PAGE_SIZE <span class=\"token operator\">-<\/span> IGB_RX_BUFSZ<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span>\n\t\t<span class=\"token keyword\">return<\/span> false<span class=\"token punctuation\">;<\/span>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">endif<\/span><\/span>\n\n\t<span class=\"token comment\">\/* bump ref count on page before it is given to the stack *\/<\/span>\n\t<span class=\"token comment\">\/\/ref count +1 \u540e\u9001\u7ed9\u534f\u8bae\u6808\uff0c\u534f\u8bae\u6808\u7528\u5b8c\u4e86\u4f1a -1<\/span>\n\t<span class=\"token function\">get_page<\/span><span class=\"token punctuation\">(<\/span>page<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token keyword\">return<\/span> true<span class=\"token punctuation\">;<\/span>\n<span class=\"token punctuation\">}<\/span>\n\n<\/code><\/pre>\n<p>igb_reuse_rx_page \u5c31\u662f reuse \u7684\u51fd\u6570\uff0c\u8fd9\u90e8\u5206\u4e5f\u5c31\u662f\u628a\u65e7\u7684 page \u7684\u53cd\u9762\u8d4b\u7ed9 next_to_alloc\uff0c\u8fd9\u65f6\u5019\uff0coffset \u7684\u503c\u5df2\u7ecf\u6539\u53d8\uff0c\u5373\u9875\u9762\u5df2\u7ecf\u7ffb\u8f6c\u4e86\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u6210\u529f\u5730\u5c06\u53ef\u4ee5\u4f7f\u7528\u7684 buffer \u4ece next_to_clean \u7ed9\u5230\u4e86 next_to_alloc\u3002<\/p>\n<pre><code class=\"prism language-c\"><span class=\"token comment\">\/** * igb_reuse_rx_page - page flip buffer and store it back on the ring * @rx_ring: rx descriptor ring to store buffers on * @old_buff: donor buffer to have page reused * * Synchronizes page for reuse by the adapter **\/<\/span>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">igb_reuse_rx_page<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_ring<\/span> <span class=\"token operator\">*<\/span>rx_ring<span class=\"token punctuation\">,<\/span>\n\t\t\t <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_rx_buffer<\/span> <span class=\"token operator\">*<\/span>old_buff<span class=\"token punctuation\">)<\/span>\n<span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_rx_buffer<\/span> <span class=\"token operator\">*<\/span>new_buff<span class=\"token punctuation\">;<\/span>\n\tu16 nta <span class=\"token operator\">=<\/span> rx_ring<span class=\"token operator\">-><\/span>next_to_alloc<span class=\"token punctuation\">;<\/span>\n\n\tnew_buff <span class=\"token operator\">=<\/span> <span class=\"token operator\">&<\/span>rx_ring<span class=\"token operator\">-><\/span>rx_buffer_info<span class=\"token punctuation\">[<\/span>nta<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* update, and store next to alloc *\/<\/span>\n\t<span class=\"token comment\">\/\/nta \u7684 update \u5728\u540e<\/span>\n\tnta<span class=\"token operator\">++<\/span><span class=\"token punctuation\">;<\/span>\n\trx_ring<span class=\"token operator\">-><\/span>next_to_alloc <span class=\"token operator\">=<\/span> <span class=\"token punctuation\">(<\/span>nta <span class=\"token operator\"><<\/span> rx_ring<span class=\"token operator\">-><\/span>count<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">?<\/span> nta <span class=\"token operator\">:<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* transfer page from old buffer to new buffer *\/<\/span>\n\t<span class=\"token comment\">\/\/\u8fd9\u91cc\u7684 old buffer \u662f next_to_clean \u5bf9\u5e94\u7684 page \u53cd\u8f6c\u540e\u5bf9\u5e94\u7684 buffer<\/span>\n\t<span class=\"token operator\">*<\/span>new_buff <span class=\"token operator\">=<\/span> <span class=\"token operator\">*<\/span>old_buff<span class=\"token punctuation\">;<\/span>\n\n\t<span class=\"token comment\">\/* sync the buffer for use by the device *\/<\/span>\n\t<span class=\"token function\">dma_sync_single_range_for_device<\/span><span class=\"token punctuation\">(<\/span>rx_ring<span class=\"token operator\">-><\/span>dev<span class=\"token punctuation\">,<\/span> old_buff<span class=\"token operator\">-><\/span>dma<span class=\"token punctuation\">,<\/span>\n\t\t\t\t\t old_buff<span class=\"token operator\">-><\/span>page_offset<span class=\"token punctuation\">,<\/span>\n\t\t\t\t\t IGB_RX_BUFSZ<span class=\"token punctuation\">,<\/span>\n\t\t\t\t\t DMA_FROM_DEVICE<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n<span class=\"token punctuation\">}<\/span>\n<\/code><\/pre>\n<h2>\u56db\u3001\u7ffb\u8f6c\u9875\u9762<\/h2>\n<p>page reuse \u6700\u6838\u5fc3\u7684\u90e8\u5206\u5c31\u662f\u7ffb\u8f6c\u9875\u9762\uff08\u5373\u4e0a\u9762\u63d0\u5230\u7684 flip page offset to other buffer\uff09\u3002\u8fd9\u662f\u4ec0\u4e48\u610f\u601d\u5462\uff1fPAGE_SIZE \u4e00\u822c\u4e3a 4096\uff0cpage->offset \u7684\u521d\u59cb\u503c\u4e3a 0\u3002\u4e0b\u9762\u8fd9\u53e5\u4ee3\u7801\u6267\u884c\u5f02\u6216\u8fd0\u7b97\uff0c\u800cIGB_RX_BUFSZ \u7684\u503c\u4e3a 2048\u3002\u90a3\u4e48 page->offset \u7684\u503c\u5c31\u5728 0 \u548c 2048 \u4e4b\u95f4\u6765\u56de\u53d8\u6362\uff0c\u5373\u6709\u4e24\u4e2a\u7f13\u5b58\u533a\uff0c0 ~ 2047\u30012048 ~ 4095\u3002<\/p>\n<pre class=\"language-java prettyprint linenums\"><code class=\"prism language-c\"><span class=\"token comment\">\/* flip page offset to other buffer *\/<\/span>\nrx_buffer<span class=\"token operator\">-><\/span>page_offset <span class=\"token operator\">^=<\/span> IGB_RX_BUFSZ<span class=\"token punctuation\">;<\/span>\n<\/code><\/pre>\n<p>\u5982\u4e0b\u56fe\u6240\u793a\uff0c\u56fe\u4e2d\u9634\u5f71\u90e8\u5206\u8868\u793a\u7f13\u5b58\u533a 0 ~ 2047\uff0c\u7a7a\u767d\u90e8\u5206\u4e3a 2048 ~ 4095\u3002\u8fd9\u6837\u7684\u8f6c\u6362\u662f\u4e00\u79cd ping-pong \u673a\u5236\uff0c\u53ef\u4ee5\u79f0\u4e4b\u4e3a ping-pong page\u3002\u5728\u672c\u6587\u4e2d\u6211\u79f0\u8fd9\u79cd\u673a\u5236\u4e3a page \u7684\u6b63\u53cd\u9762\uff0c\u5f53\u7136 page \u662f\u6ca1\u6709\u6b63\u53cd\u9762\u7684\uff0c\u53ea\u662f\u4e00\u79cd\u5e2e\u52a9\u7406\u89e3\u7684\u53eb\u6cd5\u800c\u5df2\u3002<br \/> <img decoding=\"async\" src=\"https:\/\/img.mushiming.top\/app\/mushiming_com\/4781622a464941348b5762b403f46958.png\" =\"\" =\"ping-pong page\" alt=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse (https:\/\/mushiming.com\/) \u7b2c1\u5f20\" title=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse \u7b2c1\u5f20-\u7a46\u4e16\u660e\u535a\u5ba2\" ><br \/> \u5728\u6b64\u57fa\u7840\u4e0a\uff0cigb_can_reuse_rx_page \u4e2d\u5224\u65ad\u662f\u5426\u53ef\u4ee5 reuse page\uff0c\u5982\u679c\u4e0d\u53ef\u4ee5 reuse \u90a3\u4e48\u5c31\u91cd\u65b0alloc\u3002\u8fd9\u91cc\u9762\u7684\u4e00\u79cd\u60c5\u51b5\u662f\uff0cpage \u7684\u4e00\u9762\u4ecd\u88ab\u4f7f\u7528\uff0c\u5c31\u4e0d\u53ef\u4ee5 reuse page\uff0c\u90a3\u4e48\u5c31\u9700\u8981\u91cd\u65b0 alloc \u4e00\u4e2a page \u7ed9 next_to_alloc\u3002<\/p>\n<h2>\u4e94\u3001\u6d41\u7a0b\u56fe\u793a<\/h2>\n<h3>1. \u4e3a desc alloc buffer<\/h3>\n<p>igb_configure => igb_alloc_rx_buffers\u3002<\/p>\n<pre><code class=\"prism language-c\">\t<span class=\"token comment\">\/* call igb_desc_unused which always leaves * at least 1 descriptor unused to make sure * next_to_use != next_to_clean *\/<\/span>\n\t <span class=\"token comment\">\/\/\u8fd9\u91cc\u8981\u4fdd\u8bc1\u59cb\u7ec8\u6709\u4e00\u4e2a desc \u662f\u672a\u66fe\u88ab\u4f7f\u7528\u7684\uff0c\u5c31\u662f\u4e0b\u56fe\u7684 255<\/span>\n\t<span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span>i <span class=\"token operator\">=<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span> i <span class=\"token operator\"><<\/span> adapter<span class=\"token operator\">-><\/span>num_rx_queues<span class=\"token punctuation\">;<\/span> i<span class=\"token operator\">++<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{ \n <!-- --><\/span>\n\t\t<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">igb_ring<\/span> <span class=\"token operator\">*<\/span>ring <span class=\"token operator\">=<\/span> adapter<span class=\"token operator\">-><\/span>rx_ring<span class=\"token punctuation\">[<\/span>i<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span>\n\t\t<span class=\"token function\">igb_alloc_rx_buffers<\/span><span class=\"token punctuation\">(<\/span>ring<span class=\"token punctuation\">,<\/span> <span class=\"token function\">igb_desc_unused<\/span><span class=\"token punctuation\">(<\/span>ring<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>\n\t<span class=\"token punctuation\">}<\/span>\n<\/code><\/pre>\n<p>\u8fd9\u91cc\u4e3a num_rx_desc \u4e2a desc \u5206\u914d\u4e86 page\uff0ccode \u6267\u884c\u5b8c\u6bd5\u540e\uff0cnext_to_alloc = next_to_use = num_rx_desc -1\uff0cnext_to_clean = 0\u3002<br \/> <img decoding=\"async\" src=\"https:\/\/img.mushiming.top\/app\/mushiming_com\/594477022bb44880a25851d239f07cd2.png\" =\"\" =\"\u5f00\u59cb\" alt=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse (https:\/\/mushiming.com\/) \u7b2c2\u5f20\" title=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse \u7b2c2\u5f20-\u7a46\u4e16\u660e\u535a\u5ba2\" ><\/p>\n<h3>2. page reuse ok<\/h3>\n<h4>2.1 \u4e00\u4e2a packet\uff0c\u4e00\u4e2a desc<\/h4>\n<p>\u8fd9\u91cc\u4e3a\u4e86\u5e2e\u52a9\u7406\u89e3\uff0c\u8ba9\u6211\u4eec\u4ece\u5934\u5f00\u59cb\uff0c\u7b2c\u4e00\u6b21\u6536\u5230\u4e00\u4e2a\u5305\uff0c\u4e14\u53ea\u7528\u5230\u4e00\u4e2a desc\uff0c\u7136\u540e\u5f00\u59cb\u5904\u7406\u3002<br \/> \uff081\uff09 cleaned_count = 0\uff0c\u90a3\u4e48\u6b64\u5904\u4e0d\u7528 alloc rx buffer\u3002<br \/> \uff082\uff09igb_fetch_rx_buffer\uff0c\u7ecf\u8fc7\u8fd9\u91cc\uff0cnext_to_clean \u7684 page \u7ffb\u8f6c\u540e\u7ed9\u5230\u4e86 next_to_alloc\uff0cnext_to_alloc = 0\u3002\u8fd9\u91cc\u662f\u628a desc 0 \u7684 page \u7684\u53cd\u9762\u7ed9 desc 255\u3002\u6ce8\u610f\uff0c\u8fd9\u91cc desc 0 \u7684 page \u5df2\u7ecf\u88ab\u6e05\u7a7a\u4e86\u3002<br \/> \uff083\uff09cleaned_count = 1\u3002<br \/> \uff084\uff09igb_is_non_eop\uff0cnext_to_clean = 1\u3002<br \/> \uff085\uff09cleaned_count = 1\uff0calloc buffer\uff0c\u56e0\u4e3a desc 255 \u5df2\u7ecf\u88ab next_to_clean \u8d4b\u4e88\u4e86 desc 0 \u7684 page\uff0c\u56e0\u6b64\u4e0d\u9700\u8981 alloc page\uff0cnext_to_alloc = next_to_use = 0\u3002<br \/> <img decoding=\"async\" src=\"https:\/\/img.mushiming.top\/app\/mushiming_com\/7e95824ad3054c9290fecac25074c464.png\" =\"\" =\"1descok\" alt=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse (https:\/\/mushiming.com\/) \u7b2c3\u5f20\" title=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse \u7b2c3\u5f20-\u7a46\u4e16\u660e\u535a\u5ba2\" ><\/p>\n<h4>2.2 \u4e00\u4e2a packet\uff0c\u591a\u4e2a desc<\/h4>\n<p>\u591a\u4e2a desc \u7684\u60c5\u51b5\u548c\u4e00\u4e2a desc \u662f\u7c7b\u4f3c\u7684\uff0c\u4ecd\u7136\u662f\u4e00\u4e2a\u5305\u3002<br \/> \uff081\uff09 cleaned_count = 0\uff0c\u90a3\u4e48\u6b64\u5904\u4e0d\u7528 alloc rx buffer\u3002<br \/> \uff082\uff09igb_fetch_rx_buffer\uff0c\u7ecf\u8fc7\u8fd9\u91cc\uff0cnext_to_clean \u7684 page \u7ffb\u8f6c\u540e\u7ed9\u5230\u4e86 next_to_alloc\uff0cnext_to_alloc = 0\u3002\u8fd9\u91cc\u662f\u628a desc 0 \u7684 page \u7684\u53cd\u9762\u7ed9 desc 255\u3002\u6ce8\u610f\uff0c\u8fd9\u91cc desc 0 \u7684 page \u5df2\u7ecf\u88ab\u6e05\u7a7a\u4e86\u3002<br \/> \uff083\uff09cleaned_count = 1\u3002<br \/> \uff084\uff09igb_is_non_eop\uff0cnext_to_clean = 1\u3002\u56e0\u4e3a\u4e0d\u662f end of packet\uff0c\u6240\u4ee5 continue\u3002<br \/> \uff085\uff09\u91cd\u590d\u4e09\u6b21\uff1a\u7b2c\u4e00\u6b21\u91cd\u590d\uff0c\u628a desc 1 \u7684 page \u53cd\u9762\u7ed9\u5230 desc 0\uff0cnext_to_alloc = 1\uff0ccleaned_count = 2\uff0cnext_to_clean = 2\uff1b\u7b2c\u4e8c\u6b21\u91cd\u590d\uff0c\u628a desc 2page \u7684\u53cd\u9762\u7ed9\u5230 desc 1\uff0cnext_to_alloc = 2\uff0ccleaned_count = 3\uff0cnext_to_clean = 3\uff1b\u7b2c\u4e09\u6b21\u91cd\u590d\uff0c\u628a desc 3page \u7684\u53cd\u9762\u7ed9\u5230 desc 2\uff0cnext_to_alloc = 3\uff0ccleaned_count = 4\uff0cnext_to_clean = 4\u3002<br \/> \uff086\uff09cleaned_count = 4\uff0crx alloc buffer\uff0c\u4f46\u662f\u56e0\u4e3a desc 255\u30010\u30011\u30012\uff0c\u90fd\u662f\u6709\u5bf9\u5e94\u7684 page \u7684\uff0c\u6240\u4ee5\u4e0d\u9700\u8981 alloc\uff0cnext_to_use = 3\u3002<br \/> <img decoding=\"async\" src=\"https:\/\/img.mushiming.top\/app\/mushiming_com\/422defa3b1004b5883091a81d0d732d3.png\" =\"\" =\"\u591adescok\" alt=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse (https:\/\/mushiming.com\/) \u7b2c4\u5f20\" title=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse \u7b2c4\u5f20-\u7a46\u4e16\u660e\u535a\u5ba2\" ><\/p>\n<h3>3. page reuse fail<\/h3>\n<h4>3.1 \u4e00\u4e2a packet\uff0c\u4e00\u4e2a desc<\/h4>\n<p>\u8fd9\u91cc\u4e3a\u4e86\u5e2e\u52a9\u7406\u89e3\uff0c\u8ba9\u6211\u4eec\u4ece\u5934\u5f00\u59cb\uff0c\u7b2c\u4e00\u6b21\u6536\u5230\u4e00\u4e2a\u5305\uff0c\u4e14\u53ea\u7528\u5230\u4e00\u4e2a desc\uff0c\u7136\u540e\u5f00\u59cb\u5904\u7406\u3002<br \/> \uff081\uff09cleaned_count = 0\uff0c\u90a3\u4e48\u6b64\u5904\u4e0d\u7528 alloc rx buffer\u3002<br \/> \uff082\uff09igb_fetch_rx_buffer\uff0c\u8fd9\u91cc dma_unmap_page\uff0cdesc 0 page != NULL\u3002<br \/> \uff083\uff09cleaned_count =1\u3002<br \/> \uff084\uff09igb_is_non_eop\uff0cnext_to_clean = 1\u3002<br \/> \uff085\uff09cleaned_count =1\uff0calloc rx buffer\uff0cigb_alloc_mapped_page \u8fd9\u91cc\u56e0\u4e3a desc 255 \u7684 page \u662f\u6ca1\u6709\u5206\u914d\u7684\uff0c\u6240\u4ee5\u5206\u914d\u4e00\u4e2a page\uff0cnext_to_alloc = next_to_use = 0\u3002<br \/> <img decoding=\"async\" src=\"https:\/\/img.mushiming.top\/app\/mushiming_com\/e5f3e2a0a6d04b3cb82cb25ea1d5bea0.png\" =\"\" =\"1descfail\" alt=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse (https:\/\/mushiming.com\/) \u7b2c5\u5f20\" title=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse \u7b2c5\u5f20-\u7a46\u4e16\u660e\u535a\u5ba2\" ><\/p>\n<h4>3.2 \u4e00\u4e2a packet\uff0c\u591a\u4e2a desc<\/h4>\n<p>\u7136\u540e\u662f\u591a\u4e2a desc\uff0c\u4e00\u4e2a packet \u7684\u60c5\u51b5\u3002\u5047\u8bbe\u662f\u56db\u4e2a desc\uff0c\u4e14 desc 2 \u6240\u5bf9\u5e94\u7684 page \u65e0\u6cd5\u88ab reuse\u3002<br \/> \uff081\uff09cleaned_count = 0\uff0c\u90a3\u4e48\u6b64\u5904\u4e0d\u7528alloc rx buffer\u3002<br \/> \uff082\uff09igb_fetch_rx_buffer\uff0c\u7ecf\u8fc7\u8fd9\u91cc\uff0cnext_to_clean \u7684 page \u7ffb\u8f6c\u540e\u7ed9\u5230\u4e86 next_to_alloc\uff0cnext_to_alloc = 0\u3002\u8fd9\u91cc\u662f\u628a desc 0 \u7684 page \u7684\u53cd\u9762\u7ed9 desc 255\u3002\u6ce8\u610f\uff0c\u8fd9\u91cc desc 0 \u7684 page \u5df2\u7ecf\u88ab\u6e05\u7a7a\u4e86\u3002<br \/> \uff083\uff09cleaned_count = 1\u3002<br \/> \uff084\uff09igb_is_non_eop\uff0cnext_to_clean = 1\u3002\u56e0\u4e3a\u4e0d\u662f end of packet\uff0c\u6240\u4ee5 continue\u3002<br \/> \uff085\uff09igb_fetch_rx_buffer\uff0c\u7ecf\u8fc7\u8fd9\u91cc\uff0cnext_to_clean \u7684 page \u7ffb\u8f6c\u540e\u7ed9\u5230\u4e86 next_to_alloc\uff0cnext_to_alloc = 1\u3002\u8fd9\u91cc\u662f\u628a desc 1 \u7684 page \u7684\u53cd\u9762\u7ed9 desc 0\u3002\u6ce8\u610f\uff0c\u8fd9\u91cc desc 1 \u7684 page \u5df2\u7ecf\u88ab\u6e05\u7a7a\u4e86\u3002<br \/> \uff086\uff09cleaned_count = 2\u3002<br \/> \uff087\uff09igb_is_non_eop\uff0cnext_to_clean = 2\u3002\u56e0\u4e3a\u4e0d\u662f end of packet\uff0c\u6240\u4ee5 continue\u3002<br \/> \uff088\uff09igb_fetch_rx_buffer\uff0cdesc 2 \u7684 page \u662f\u65e0\u6cd5 reuse \u7684\uff0c\u56e0\u6b64 dma_unmap_page\uff0cdesc 2 page != NULL\u3002<br \/> \uff089\uff09cleaned_count = 3\u3002<br \/> \uff0810\uff09igb_is_non_eop\uff0cnext_to_clean = 3\u3002\u56e0\u4e3a\u4e0d\u662f end of packet\uff0c\u6240\u4ee5 continue\u3002<br \/> \uff0811\uff09igb_fetch_rx_buffer\uff0c\u7ecf\u8fc7\u8fd9\u91cc\uff0cnext_to_clean \u7684 page \u7ffb\u8f6c\u540e\u7ed9\u5230\u4e86 next_to_alloc\uff0cnext_to_alloc = 2\u3002\u8fd9\u91cc\u662f\u628a desc 3 \u7684 pag e\u7684\u53cd\u9762\u7ed9\u4e86 desc 1\u3002\u6ce8\u610f\uff0c\u8fd9\u91cc desc 3 \u7684 page \u5df2\u7ecf\u88ab\u6e05\u7a7a\u4e86\u3002<br \/> \uff0812\uff09cleaned_count = 4\u3002<br \/> \uff0813\uff09igb_is_non_eop\uff0cnext_to_clean = 4\u3002\u662f end of packet\u3002<br \/> \uff0814\uff09cleaned_count = 4\uff0calloc rx buffer\uff0c\u5bf9\u4e8e desc 255\u30010\u30011\u30012\uff0c\u9664\u4e86 desc 2 \u662f\u7a7a\u5916\uff0c\u53e6\u5916\u4e09\u4e2a\u90fd\u662f\u6709 page \u7684\uff0c\u6240\u4ee5\u53ea\u9700\u8981 alloc \u4e00\u4e2a page \u7ed9 desc 2\u3002\u540e\u7eed next_to_alloc = next_to_clean = 3\u3002<br \/> <img decoding=\"async\" src=\"https:\/\/img.mushiming.top\/app\/mushiming_com\/5576f3a4a7754ab0aba4509cf5e0a308.png\" =\"\" =\"\u591adescfail\" alt=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse (https:\/\/mushiming.com\/) \u7b2c6\u5f20\" title=\"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse \u7b2c6\u5f20-\u7a46\u4e16\u660e\u535a\u5ba2\" ><\/p>\n<h2>\u516d\u3001\u603b\u7ed3\u8bed<\/h2>\n<p>\u81f3\u6b64\uff0cpage reuse \u5df2\u7ecf\u8bb2\u5b8c\u4e86\uff0c\u5176\u5b9e\u4e00\u5f00\u59cb\u6211\u53ea\u6253\u7b97\u4ecb\u7ecd igb_fetch_rx_buffer\uff0c\u4f46\u662f\u603b\u611f\u89c9\u6709\u4e9b\u96be\u53d7\uff0c\u6240\u4ee5\u540e\u7eed\u53c8\u8865\u5145\u4e86 Rx \u7684\u5176\u4ed6\u4e00\u4e9b\u5206\u6790\uff0c\u5e0c\u671b\u5927\u5bb6\u80fd\u591f\u6ee1\u610f\u3002<\/p>\n<p>\u5982\u679c\u89c9\u5f97\u8fd9\u7bc7\u6587\u7ae0\u6709\u7528\u7684\u8bdd\uff0c\u53ef\u4ee5\u70b9\u8d5e\u3001\u8bc4\u8bba\u6216\u8005\u6536\u85cf\uff0c\u4e07\u5206\u611f\u8c22\uff0cgoodbye~<\/p>\n","protected":false},"excerpt":{"rendered":"\u7f51\u5361\u9a71\u52a8\u6536\u5305\u4ee3\u7801\u5206\u6790\u4e4b page reuse\u6700\u8fd1\u5728\u5b66\u4e60Intel\u7684igbkerneldriver\u7684Rxpagereuse\u90e8\u5206\uff0c\u5b66\u4e60\u7ed3\u675f\u4f5c\u4e00\u4e2a\u603b\u7ed3","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"_links":{"self":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts\/9156"}],"collection":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/comments?post=9156"}],"version-history":[{"count":0,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts\/9156\/revisions"}],"wp:attachment":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/media?parent=9156"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/categories?post=9156"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/tags?post=9156"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}