Research And Solutions Of The Overload Problem About Net Packets Receiving

The computer industry has developed into the stage which is called 'post-PC, the new words such as information appliance and set-top box become more and more familiar to people, and the research on embedded system becomes a hotspot in the computer domain. As the abroad use of the embedded systems, the embedded devices will inevitably be connected to Internet, which makes it convenient for the long-distance visit, check and control. However, when the embedded device is frequently visited or balefully attacked, the embedded system will easily turn into a overload stage, because of its low handling rate and limited resources.In this paper, the overload problem about net packets receiving is researched in the environment of HHARM2410 and ARM Linux. By analyzing the process of net packets receiving, the process can be divided into two parts, the NIC interrupt handling and the TCP/IP handling. When data packets come to the NIC buffer, the interrupt service routine will be triggered. After the handling of the NIC interrupt, the data packets will be as the input of the TCP/IP handling, waiting for the handling of TCP/IP. The two handling processes share the same processor, and priority of NIC interrupt is higher, so it will appear the situation that data packets are continuously received from networks, but these packets can't be handled by TCP/IP. This phenomenon is the overload problem which will be researched in this paper, called "receive livelock".After analyzing with the M/M/1 model in the queue theory, the conclusion is drawn that lower the NIC interrupt frequency can solve the overload problem. On the basis of analyzing, three solutions are brought forward, they are batch interrupt, disable interrupt and poll. Design the testing plan for the three solutions, and the result is that when the overload is light, the batch interrupt and the poll can solve...