Research And Application Of Lock-free Memory Allocation And Reliable UDP Technology

With the continuous progress of communication technology,Shortwave communication,a traditional communication method,has also developed rapidly.Because of its advantages,it has always been valued.The transmission distance of short wave signal is far,it is one of the main means of remote communication.And,it is the only long-distance communication mode not restricted by network hub and active relay.Shortwave is widely used in civil and military fields,So it is very important to monitor and detect the short wave signal.The short wave signal monitoring and analysis system needs to meet the requirements of real-time,high-speed data flow,distributed display and control,etc.A good memory allocation algorithm can improve the efficiency and stability of the real-time system.Buddy algorithm is a common memory allocation algorithm,and it is adopted by Linux systems.But it still has a series of shortcomings.For real-time systems,frequently request and release memory from the operating system is not only inefficient,but also detrimental to the stability of the system.For the shortcomings of Buddy memory allocation algorithm,and the characteristics of the short wave display and control system that need to allocate memory frequently.This thesis proposes a lock-free memory allocation algorithm that runs on the application layer.It has higher allocation efficiency than Buddy algorithm,especially in high concurrency environment.In high-speed real-time system,it is often necessary to apply for some short-lived memory frequently,and this will cause the buddy algorithm to continuously split and merge memory blocks.In order to solve this problem,this thesis proposes an incremental remerging algorithm.It not only reduces the split and merge of memory blocks,improves the average response speed of allocation algorithm,but also reduces the external fragmentation rate.Aiming at the deficiency of TCP protocol in wired/wireless heterogeneous network environment.And,real time data transmission requirements of short wave display and control system.This thesis makes use of the high plasticity of UDP protocol,designs a Reliable UDP protocol,which has many improvements compared with TCP protocol.Such as:RTT estimation algorithm with dynamic smoothing factor improves the accuracy of RTT estimation.The efficiency of congestion control algorithm is improved by improving bandwidth estimation algorithm.In order to solve the problem of retransmission of overdue data,a fast algorithm of discarding time-out data is proposed.Finally,the experimental results show that the efficiency of the lock-free memory allocation algorithm is higher than the Buddy algorithm.In the actual production environment,the efficiency of Reliable UDP protocol and TCP protocol is compared,it is proved that Reliable UDP protocol has higher efficiency.