One tool that we use is called upshot, which is a derivative of Upshot [9], written in Tcl/Tk. A screen dump of Upshot in use is shown in Figure 1 .
It shows parallel time lines with process states, like one of the paraGraph [8]. The view can be zoomed in or out, horizontally or vertically, centered on any point in the display chosen with the mouse. In Figure 1 , 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.
Nupshot is a version of upshot that is faster but requires an older version of Tcl/tk.