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2.2 Understanding the Preview Drawable

A preview drawable is created as a result of the renormalization process of the SLOG-2 format. The renormalized object provides a high-level description of what is going on within the (timeline vs time) region where the prevew object spans. Preview drawable is designed to amalgamate real drawables of same topological type, e.g. preview state amalgamates only states. So preview drawable is always a primitive drawable in the renormalization scheme. There are currently 3 different types of preview drawables: Preview_State, Preview_Arrow, and Preview_Event. Therefore one preview drawable is for each supported topology of primitive drawable. The three preview categories will always show up in the Legend window of the display program as shown in Figure 3.2 disregarding of the presence of preview drawables in the slog2 file. The Legend window contains a table of legends. Each legend provides an interface to the user modifiable part of the corresponding category that is relevant to the display program.

Figures 2.1 to 2.5 illustrate the visual transition from preview drawable to its detailed content of the first 5 processes of a 16 processes MPI slog2 file when the timeline canvas is being zooming-in. The sequence of figures is generated by zooming in a marked region in each figure in the sequence. The marked region is shaded and is bounded by a pair of white lines. A magnifying glass with plus sign in the center is the cursor that marks the end of the zoom region. Figure 2.1 is a typical timeline canvas where most of real drawables are still buried by their preview drawables. In the figure, there are preview arrows, preview states and some long running real states.

Figure 2.1: A typical zoom-out view of preview states and arrows.
Image timeline_preview_detail_0

Each thick yellow line is a preview arrow which represents a collection of arrows between its 2 ending timelines. The start and final timestamps of preview arrow are the extremes of all real arrows amalgamated inside the preview object. Notice that the beginning or ending timestamp of a preview arrow does not necessarily mean that there is an arrow starting or ending at that time, it just indicates that there are arrows starting and ending within these 2 times and between the 2 marked timelines.

The rectangle that has horizontal strips of colors is preview state. The different colors inside a preview state represent the various categories of real states that are amalgamated within the time range of the preview state. Depending on the PREVIEW_STATE_DISPLAY option selected in Preference window as shown in Figure 3.19 and in Table 3.12, the distribution and the heights of the strips can be changed as well. The default display option for preview state is DECRE_WEIGHT_ORDER. In this option, the strips are arranged in decreasing height order. The tallest strip at the bottom of the preview state corresponds to the category of states that contribute cumulatively the longest duration in specified time range. This visual representation aims to tell what state categories could be within the span of the preview state and which state category contributes the most statistically to the specified time range, so user can decide where to zoom in to find out more details. In a sense, the preview states provide a global coarse-grain summary of what is going on without losing as much details as the preview found in older Jumpshot, i.e. Jumpshot-3. Compared with Jumpshot-3's preview which has averaged out the timeline ID information, the new preview states retain the timeline ID information and that may lead to early detection of load balancing problem before zooming into seeing all the real states.

Figure 2.2: The next zoom-in view of Figure 2.1.

Image timeline_preview_detail_1

Figure 2.2 shows a more zoom-in view of the region marked by the pair of white lines in Figure 2.1. As shown in Figure 2.2, some of the preview arrows have disappeared and are replaced by real arrows, the white arrow. Also, some of the stripped preview states have split into several preview states of one single color, i.e. the white and grey states, to show more detailed distribution. Another important feature of preview state becomes apparent in the figures: Preview states are properly nested within real states. In the most expanded Y-axis label view, preview state is always on top of other nested states2.2, i.e. states that enclose the preview state are alway real states. A good visual example is shown in Figure 2.2 where all the white, turquoise and grey preview states2.3 are sitting on top of the long orange and dark royal blue states. This indicates that the white, turquoise and grey real states will be all nested inside the long running orange and dark royal blue states.

Figure 2.3: The next zoom-in view of Figure 2.2.

Image timeline_preview_detail_2

Figure 2.3 is the zoom-in view of the region marked by the pair of white lines in Figure 2.2. Comparing these 2 figures, all the preview drawables have disappeared and are replaced by real drawables. Each white preview state are repleaced by hundreds of white real states, the same is also true for the grey preview states that sit to the right of the turquoise states2.4. The preview arrows are all replaced by the real arrows. It becomes apparent that the white lines marked region in Figure 2.2 provides a good description of what is going on in Figure 2.3 but at the same time it reduces the number of drawables drawn on the canvas by a factor of 100. Another way of seeing this benefit is to find out the exact number of real drawables amalgamated by the preview objects within the zoomed region. This can be achieved by right clicking on the preview drawable and the result is shown in Figure 3.13.

Figure 2.4: The next zoom-in view of Figure 2.3.

Image timeline_preview_detail_3

Further zooming into the white lines marked region in Figure 2.3 enlarges the real drawables that are displayed in the figure. The enlarged view is shown in Figure 2.4. The densely packed states and arrows become more distinguishable. Another zooming in the whit lines marked region in Figure 2.4 enlarges the real drawables into easily separable objects as shown in Figure 2.5.

Figure 2.5: The next zoom-in view of Figure 2.4.

Image timeline_preview_detail_4



Footnotes

... states2.2
Only in slog2 file that has multiple ViewMaps and where timelines can be collapsed, i.e. AIX's UTE generated slog2 file, preview state can be nested with other preview state in collapsed Y-axis label view.
... states2.3
when a preview state contains only real states of one single category, it will appear like a real state in the timeline canvas. The only way to tell the difference is to bring up the Drawable Info Box by right clicking on the state.
... states2.4
In order to speed up grahics performance of the display program, an aggressive algorithm has been employed to eliminate drawing states that are closely packed together within the nearest neighboring pixels. Together with the fact that the number of pixels available is less than the number of non-overlap states in the region, the number of the real states may sometimes not appear as numerous as the Drawable Info Box of preview state indicates. In that case, a further zoom in will be needed to confirm the case as shown in Fig. 2.4.

next up previous contents
Next: 3. Graphical User Interface Up: 2. Data Model Previous: 2.1 Understanding the Drawable   Contents