Research And Implementation Of An Efficient Interaction Mechanism Of Hardware And Software Supporting Zero-copy Technology In CIA Network Card

As the rapid growth of network bandwith, the packet capture and analysis technology is being widely used. Through analyzing the captured packets, we can analysis the network bottlenecks, find out the illegal content in the captured packets.Traditional packet capture system spends a lot of resources to interrupt, memory copy, system call and protocol processing. To improve the performance of capturing packets, the packet capture system widely used zero-copy technology. The zero-copy packet capture system has achieved zero system call, zero memory copy, avoiding a complex protocol processing in Linux kernel, however it dose not consider the interrupt overhead. It is this paper's purpose that to improve the performance of the zero-copy packet capture system by reducing interrupt overhead.Interrupt overhead relates to data exchange mechanism between network adapter and host memory, and Linux system interrupt handling process for the network adapter.The main work and innovation of this paper are as fallows. Firstly this paper analysed the data exchange mechanism between high-speed network adapter and host memory.Secondly this paper analysed the mechanism that how the network adapter gets the descriptors.Thirdly this paper established an abstract model for descriptor buffers in host memory and network adapter.Fourthly this paper analysed the interrupt process in Linux system for the network adapter, compared the advantages and disadvantages of interrupt-driven and polling-driven mechanism, introduced the semi-polling mechanism to reduce interrupt overhead. At the same time, the network adapter hardware used interrupt merging technology to reduce the number of interrupt. Lastly this paper used the buffer pool technology to reduce the interrupt time that the Linux system spends on the network adapte.