View figure.
The primary difference between Xprofiler and the UNIX(R) gprof command is that Xprofiler gives you a graphical picture of your application's CPU consumption in addition to textual data. This allows you to focus quickly on the areas of your application that consume a disproportionate amount of CPU.
Xprofiler displays your profiled program in a single main window. It uses several types of graphic images to represent the relevant parts of your program. Functions appear as solid green boxes (called function boxes), and the calls between them appear as blue arrows (called call arcs). The function boxes and call arcs that belong to each library within your application appear within a fenced-in area called a cluster box. The way that functions, calls, and library clusters are depicted is discussed later.
The Xprofiler main window contains a graphical representation of the functions and calls within your application as well as their inter-relationships. It provides six menus, including one for online help.
The Xprofiler main window looks similar to this when an application has been loaded:
Figure 7. Sample Xprofiler Main Window
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In the main window, Xprofiler displays the function call tree. The function call tree displays the function boxes, arcs, and cluster boxes that represent the functions within your application.
Along the upper portion of the main window is the menu bar. The left side of the menu bar contains the Xprofiler menus that let you work with your profiled data. On the right side of the menu bar, there is a Help menu for accessing online help.
The Xprofiler menus are described below:
The File menu lets you specify the executable (a.out) files and profile data (gmon.out) files that Xprofiler will use. It also lets you control how your files are accessed and saved.
The View menu lets you focus on specific portions of the function call tree in order to get a better view of the application's critical areas.
The Filter menu lets you add, remove, and change specific parts of the function call tree. By controlling what Xprofiler displays, you can focus on the objects that are most important to you.
The Report menu provides several types of profiled data in a textual and tabular format. In addition to presenting the profiled data, the options of the Report menu let you:
The Utility menu contains one option; Locate Function By Name, which lets you highlight a particular function in the function call tree.
The Function menu lets you perform a number of operations for any of the functions shown in the function call tree. You can access statistical data, look at source code, and control which functions get displayed.
The Function menu is not visible from the Xprofiler window. You access it by clicking on the function box of the function in which you are interested with your right mouse button. By doing this, you not only bring up the Function menu, but you select this function as well. Then, when you select actions from the Function menu, they are applied to this function.
The Arc menu lets you locate the caller and callee functions for a particular call arc. A call arc is the representation of a call between two functions within the function call tree.
The Arc menu is not visible from the Xprofiler window. You access it by clicking on the call arc in which you are interested with your right mouse button. By doing this, you not only bring up the Arc menu, but you select that call arc as well. Then, when you perform actions with the Arc menu, they are applied to that call arc.
The Cluster Node menu lets you control the way your libraries are displayed by Xprofiler. In order to access the Cluster Node Menu, the function boxes, in the function call tree, must first be clustered by library. See Clustering libraries together for information about clustering and unclustering the function boxes of your application. When the function call tree is clustered, all the function boxes within each library appear within a cluster box.
The Cluster Node menu is not visible from the Xprofiler window. You access it by clicking on the edge of the cluster box in which you are interested with your right mouse button. By doing this, you not only bring up the Cluster Node menu, but you select that cluster as well. Then, when you perform actions with the Cluster Node menu, they are applied to the functions within that library cluster.
At the bottom of the Xprofiler window is a single field that tells you:
Functions are represented by green, solid-filled boxes in the function call tree. The size and shape of each function box indicates its CPU usage. The height of each function box represents the amount of CPU time it spent on executing itself. The width of each function box represents the amount of CPU time it spent executing itself, plus its descendant functions.
This type of representation is known as summary mode. In summary mode, the size and shape of each function box is determined by the total CPU time of multiple gmon.out files used on that function alone, and the total time used by the function and its descendant functions. A function box that is wide and flat represents a function that uses a relatively small amount of CPU on itself (it spends most of its time on its descendants). On the other hand, the function box for a function that spends most of its time executing only itself will be roughly square-shaped.
Functions can also be represented in average mode. In average mode, the size and shape of each function box is determined by the average CPU time used on that function alone, among all loaded gmon.out files, and the standard deviation of CPU time for that function among all loaded gmon.out files. The height of each function node represents the average CPU time, among all the input gmon.out files, used on the function itself. The width of each node represents the standard deviation of CPU time, among the gmon.out files, used on the function itself. The average mode representation is available only when more than one gmon.out file is entered. For more information on summary mode and average mode, see Controlling the representation of the function call tree.
Under each function box in the function call tree is a label that contains the name of the function and related CPU usage data. For information on the function box labels, see Getting basic data.
The example below shows the function boxes for two functions, sub1 and printf, as they would appear in the Xprofiler display.
Figure 8. Example of Function Boxes and Arcs in Xprofiler Display
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Each function box has its own menu. To access it, place your mouse cursor over the function box of the function in which you are interested, and press the right mouse button. Each function also has an information box that lets you get basic performance numbers quickly. To access the information box, place your mouse cursor over the function box of the function in which you are interested, and press the left mouse button.
The calls made between each of the functions in the function call tree are represented by blue arrows extending between their corresponding function boxes. These lines are called call arcs. Each call arc appears as a solid blue line between two functions. The arrowhead indicates the direction of the call; the function represented by the function box it points to is the one that receives the call. The function making the call is known as the caller, while the function receiving the call is known as the callee.
Each call arc includes a numerical label that tells you how many calls were exchanged between the two corresponding functions.
Figure 8, above, shows several call arcs. For the call arc that connects sub1 and printf, sub1 is the caller and printf is the callee. The label tells you that sub1 called printf four times.
Note that each call arc has its own menu that lets you locate the function boxes for its caller and callee functions. To access it, place your mouse cursor over the call arc for the call in which you are interested, and press the right mouse button. Each call arc also has an information box that shows you the number of times the caller function called the callee function. To access the information box, place your mouse cursor over the call arc for the call in which you are interested, and press the left mouse button.
Xprofiler lets you collect the function boxes and call arcs that belong to each of your shared libraries into cluster boxes. Figure 7 shows an example of an Xprofiler display in which the libraries are clustered.
Since there will be a box around each library, the individual function boxes and call arcs will be difficult to see. If you want to see more detail, you will need to uncluster the function boxes. To do this, select the Filter menu and then the Uncluster Functions option.
When viewing function boxes within a cluster box, note that the size of each function box is relative to those of the other functions within the same library cluster. On the other hand, when all the libraries are unclustered, the size of each function box is relative to all the functions in the application (as shown in the function call tree).
Each library cluster has its own menu that lets you manipulate the cluster box. To access it, place your mouse cursor over the edge of the cluster box you are interested in, and press the right mouse button. Each cluster also has an information box that shows you the name of the library and the total CPU usage (in seconds) consumed by the functions within it. To access the information box, place your mouse cursor over the edge of the cluster box you are interested in and press the left mouse button.