并行程序性能分析中的时戳同步问题及方法

TIMESTAMP SYNCHRONISATION PROBLEM IN PARALLEL PROGRAM PERFORMANCE ANALYSIS AND ITS SOLUTION

基于事件跟踪的并行程序性能分析,就是通过分析各处理器采集的事件记录、计算程序对象的执行时间和探究事件间的相互关系,来揭示程序的性能问题。这一工作要求各处理器采集的事件时戳必须具有可比性。由于各种原因,通过测量获得的事件时戳往往是不同步的,这直接影响性能分析工作的开展。介绍处理器时钟误差的概念及产生原因、并行程序性能分析中的测量误差、时钟条件和时戳同步需求,最后介绍一种基于恒定时钟漂移的线性误差插值技术,在一定程度上解决了并行程序性能分析中的时戳同步问题。

Parallel program performance analysis based on event-trace is a method to reveal the performance of the program by analysing the event records collected by processors,computing the executed time of program object and investigating the correlation between events.These works require the event timestamps collected by processors to be comparable.Because of various reasons,the event timestamps passing to measure to acquire are usually not synchronous,which influences the performance analysis work directly.In this paper,the concept and the generation cause of processors clock offset,the measure offset in parallel program performance analysis,the clock condition and the requirements of timestamp synchronisation are discussed.Finally,a kind of technique named linear offset interpolation based on constant clock drift is introduced,which can help to some extent to solve the timestamp synchronisation problem in parallel program performance analysis.