Design And Implementation Of Real-time Data Acquisition Software System For The Multi-Channel Ionization Chamber Based On Zynq

At present,heavy ion therapy is one of the most effective means of radio therapy in cancer treatment.During the heavy ion treatment,it is necessary to process and analyze the parameters of the heavy ion beam generated by the accelerator through the hardware such as the multi-channel ionization chamber,front-end electronics and data processing circuit,among which the data signals generated by the multi-channel ionization chamber detector need to be collected for monitoring the position and profile uniformity of the heavy ion beam.Aiming at how to collect a large amount of data generated by the multi-channel ionization chamber efficiently,timely and accurately,this paper proposes an overall design scheme of real-time data acquisition software system based on Zynq platform,focusing on the real-time performance of the system and the required functions.The main work contents are as follows:Firstly,the real-time scheme of the acquisition system is determined.In order to accurately collect the data generated by the multi-channel ionization chamber,the acquisition system has a low response delay,and improves the real-time performance of the system from the aspects of system preemption and resource isolation access.The preemption feature of the system is realized by RT-Preempt patch in Linux single kernel real-time transformation scheme.By dividing system resources such as CPU,memory,and interrupt,container space with different resources can be formed.In this way,applications running simultaneously in different containers do not have access conflicts on the three system resources,which improves the predictability of program execution time and realizes resource isolation.Second,implement memory isolation access mechanism.The SMP IRQ Affinity mechanism and cpuset subsystem in cgroup can divide interrupt and CPU core resources respectively,but there is no memory isolation mechanism in Linux.Therefore,this paper designs a cache coloring method to realize isolated access to memory.Memory allocation module and cgroup cache subsystem module are designed and implemented by cache coloring method.This method allocates different memory spaces to different applications by controlling the memory management mode,so that the memory space is mapped to a specific area of the Last Level Cache(LLC),improving the stability of the program execution time.Next,design the functionality needed to implement the system.Design data acquisition driver module,data acquisition application program and data transmission module.The driver module controls the data transmitted from the PL side by DMA in PS side and provides the hardware control mechanism to the application layer.The data acquisition application program reads and saves the collected data frames in PS terminal.For the data transmission between the upper computer and the lower computer,the data transmission module realizes the function of data interaction based on the ZeroMQ high-speed communication framework.The data transfer module and data acquisition application program are run in different container space respectively to realize the isolated access to resources.When data collection is carried out,the data transmission module and data collection application program are respectively put into different container space to run,to achieve isolated access to resources.When data collection is carried out,the data transmission module and data collection application program are respectively put into different container space to run,to achieve isolated access to resources.Finally,test and evaluate the built Linux runtime environment.The experimental results show that the system can meet the actual demand,the system can effectively control the maximum delay time of the program and improve the stability of the program execution performance.In Stress and Hackbench tests,the average latency of the real-time kernel is 12.19% higher than that of the non-real-time kernel,and the maximum latency is controlled within 110 us.In the test of cache coloring,the execution time of the test program does not fluctuate significantly,and the predictability of the program execution time is enhanced.