Logfile Creation and Upshot

The second profiling library generates logfiles, which are files of timestamped events. During execution, calls to MPI_Log_event are made to store events of certain types in memory, and these memory buffers are collected and merged in parallel during MPI_Finalize. During execution, MPI_Pcontrol can be used to suspend and restart logging operations. The logfile produced at the end can be analyzed by a variety of tools. One that we use is called Upshot, which is a derivative of Upshot [6], written in Tcl/Tk. A screen dump of Upshot in use is shown in Figure .

  

Figure: A screendump from pshot

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It shows parallel time lines with process states, like one of the paraGraph [5]. The view can be zoomed in or out, horizontally or vertically, centered on any point in the display chosen with the mouse. In Figure , the middle window has resulted from zooming in on the upper window at a chosen point to show more detail. The window at the bottom of the screen show a histogram of state durations, with several adjustable parameters.