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TotalView Users Guide - CI Wiki

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Fine-Tuning Shared Library Use<br />

Figure 159: Stopping to Set a<br />

Breakpoint Question Box<br />

Selecting the Load button tells <strong>TotalView</strong> to display a file explorer dialog<br />

box that lets you navigate through your computer’s file system to locate<br />

the library. After selecting a library, <strong>TotalView</strong> reads it and displays a question<br />

box that lets you stop execution to set a breakpoint:<br />

<strong>TotalView</strong> might not read in information symbol and debugging information when you<br />

use this command. See “Controlling Which Symbols <strong>TotalView</strong> Reads” on page 246 for<br />

more information.<br />

Controlling Which Symbols <strong>TotalView</strong> Reads<br />

When debugging large programs with large libraries, reading and parsing symbols<br />

can impact performance. This section describes how you can minimize<br />

the impact that reading this information has on your debugging session.<br />

Using the preference settings and variables described in this section always slow down<br />

performance. However, for most programs, even large ones, the difference is often inconsequential.<br />

If, however, you are debugging a very large program with large libraries, significant<br />

performance improvements can occur.<br />

A shared library contains, among other things, loader and debugging symbols.<br />

Typically, loader symbols are read quite quickly. Debugging symbols<br />

can require considerable processing. The default behavior is to read all<br />

symbols. You can change this behavior by telling <strong>TotalView</strong> to only read in<br />

loader symbols or even that it should not read in any symbols.<br />

Saying “<strong>TotalView</strong> reads all symbols” isn’t quite true as <strong>TotalView</strong> often just reads in<br />

loader symbols for some libraries. For example, it only reads in loader symbols if the<br />

library resides in the /usr/lib directory. (These libraries are typically those provided with<br />

the operating system.) You can override this behavior by adding a library name to the<br />

All Symbols list that is described in the next section.<br />

Specifying Which Libraries are Read<br />

After invoking the File > Preferences command, select the Dynamic Libraries<br />

Page. (See Figure 160 on page 247.)<br />

The lower portion of this page lets you enter the names of libraries for<br />

which you need to manage the information that <strong>TotalView</strong> reads.<br />

246 Chapter 12: Debugging Programs

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