多队列(queues)网卡DMA收包方式.doc

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1、本文档介绍了多队列（queues）网卡DMA接收数据包方式：1.       Queues：增加驱动I/O能力，提供多个输入队列2.       DMA：减少CPU负载处理一． 主要数据结构Receivedescriptornodestructrxbd_desc{                u16         status;  /*StatusFields*/    /*optional*/                u16         length;  /*BufferLength*//*op

2、tional*/                u32         bufPtr;  /*BufferPointer 通常DMA指向skb->data*/ };Rx_buffer:skbstructrx_buffer{                structsk_buff*skb;                ………                };Queueringdescriptor:ring->desc包含count个structrxbd_desc和structrx_bufferStructr

3、ing{                void*desc;                                         /*descriptorringmemory*/                structrx_buffer *rx_buffer_info;/*skbdata*/                u16count;                                           /*amountof descriptors */           

4、     unsignedintsize;                             /*lengthinbytes(of  descriptors)*/                dma_addr_tdma;                                           /*phys.addressofdescriptorring*/                next_to_clean；                next_to_use；           

5、     ……..}二．主要寄存器：每个queue都有下列一组寄存器,n表示queue编号1. ReceiveDescriptorBaseAddress(RDBA[n])：存放ring->desc的dma地址2. ReceiveDescriptorLength（RDLEN[n]）: 存放该ring的描述符长度（ring->count*sizeof(structrxdb_desc)）3. ReceiveDescriptorControl（RXDCTL[n]）：queue使能控制器三.程序分析1.       在驱

6、动probe函数中为每个queue分配一个ring：staticintalloc_rx_queues(structixgbe_adapter*adapter){                intrx=0,nid=adapter->node;                 for(;rxnum_rx_queues;rx++){                                structring*ring;                                 r

7、ing=kzalloc_node(sizeof(*ring),GFP_KERNEL,nid);                                if(!ring)                                                ring=kzalloc(sizeof(*ring),GFP_KERNEL);                                if(!ring)                                          

8、      gotoerr_allocation;                                ring->count=adapter->rx_ring_count;                                ring->queue_index=rx;                                ring->reg_idx=rin