A Non-deterministic Events Log System Based On The Paravirtual VM Xen

Log system is very important for system reliability and system security. Log-and-Replay system is usually applied to system debugging, system fault recovery, reduction of spyware attacks, and so on. With the development of virtual technology, virtual machine operating system provides fewer hardware interfaces and provides a better trusted computing base, people began to study the log system on the virtual machine. There are several log-and-repay systems on the virtual machine that can log enough information for replay. However, these systems have some flaws: the WMMs they chosen have detrimental consequences for performance; some needs to modify the guest OS; the log files they provided have too large size.Based on the above analysis, this paper presents a new log system on a paravirtual VMM called Xen.The paravirtual VMM Xen has the best performance in VMMs and is a open source project. Logging contents are gotten and recorded in the hypervisor and privileged domain. Thus, we don't need to modify the logged system. The log system XLS logs the non-deterministic events of a lightweight operation system called Mini-OS. The non-deterministic events including keyboard input and time updated. Use the performance counter as the benchmark not the system time to log the precise time when the event happened. The log files are saved beyond the logged domain and organized to different structures with the different events, such as the keyboard input and time updated were saved in the different files. In this way, we could organize the modules and content more clearly, use fewer spaces to store the log files.The log system log the keyboard input and time updated on the lightweight operation system Mini-OS. In the experiments: logging the keyboard input would cost 12us and bring the overhead 0.06%; logging the time updated would cost 17us and bring the overhead 0.001%; the log file would increase 1.4MB each day. The overhead due to logging and the log file growth rate are far less than Revirt, ExecRecorder and ReTrace.