直接内存通信技术及其网卡原型研究

Research of Direct Memory Communication and NIC Prototype

针对基于PCI等传统I/O总线的网络I/O方式中网络通信性能受到相应总线接口限制的问题,提出了直接内存通信技术DMC(Direct Memory Communication,DMC)。使用此技术的DMC网卡可直接插入内存插槽中,DMC网卡上的存储空间被系统预留作为通信专用区,并使用与普通内存相同的方法进行管理和访问。待发送的数据使用写普通内存的方法直接写入DMC网卡的通信专用区中,对DMC网卡的通信专用区中收到的网络数据,用户可使用读普通内存的方法获得,从而实现了计算机内存之间的直接通信。因此,DMC技术使网络通信速度不受PCI等传统I/O总线的限制,省略了传统通信机制中网卡设备和内存之间的数据拷贝工作,具有通信速率高、通信延迟小及操作简单的特点。在高速光纤通道交换网中设计了DMC网卡原型,证明了DMC技术的正确性和可行性。

At present,the communications speed on PCI is limited by PCI bus,the number of the computer＇s memory slots is increasing,and the management of memory becomes advanced.So,in this paper,the direct memory communication method,abbreviated as DMC,was put forward.The NIC（the network interface card）based on DMC is inserted into a memory slot,and the memory on DMC-NIC is reserved as communication precinct.When user sends data,he uses the method of writing memory to place the data into communication space,and when user receives data,he uses the method of reading memory to get the data from communication space.So,the user can accomplished the direct point-to-point communications between the computers through accessing memory.The communications speed is not limited by I/O bus,and the copy between memory and NIC is omitted.We also applied DMC into the high-speed fibre channel switch network,and designed the FIFO-DMC NIC to prove that DMC is right.