The Design and Implementation of Zero-Copy for Linux

Zero-copy has been a hot research topic for a long history, which is an underlying technology to support many applications, including multimedia retrieval, datamining, efficient data transferring, and so on. Zero-copy means during message transmission, there is no data copy among memory segments on any network node. When a message is sent out, the data packets in user application space go through network interface directly and reach outside of the network; and when receiving a message , the same way is used, meaning the data packets are transmitted into user application space directly. In this paper we, present the design and implementation of zero-copy technology for the Linux (kernel version 2.6.11) operating system, by modifying its network device driver snull.c and improving on the COW (copy-on-write) technology,. The main method we used is the combination of MMAP and PROC procedures to implement the test program and the test strategies, and finally we successfully simulated the ARP protocol module with the VHDL language.