Files needed by lprof

The lprof tool must have access to three kinds of files in order to produce profiling information.

• the executable program (compiled with -ql)

• the data file associated with one or more program runs

• the source code files for the program being profiled

• Depending on which operation you request, lprof will not run if it cannot find one of these files.

When you run a profiled program. the name of the program is stored in the data file exactly as it appears on the command line. If you do not specify the -o option when you run lprof, it consults the data file to obtain the name of the program. Therefore, you may invoke lprof, specifying the name of the data file, and let lprof determine the name of the program. Because the name of the data file is not stored in the program itself, the reverse is not true: you cannot specify the name of the program and expect lprof to determine the name of the data file if it is not the default name.

The lprof tool will not be able to display data if you perform the following steps in the order shown:

1. use a relative path name for the executable file when you run your profiled program

2. run lprof from a different directory, specifying only the name of the data file (that is, without specifying the program name)

When you run lprof from a directory other than the one in which you have executed your profiled program, and you have used a relative path name when executing the profiled program, then you must specify the -o option to lprof with either the profiled program's full pathname or the program's pathname relative to your current directory. The following example illustrates this:

   $ cd $HOME
   $ mybin/a.out
   $ cd src
   $ lprof -o ../mybin/a.out -c ../a.out.cnt

Source files in a different directory

The names of the source files for the profiled program are also stored in the data file. However, only the file names, not the directories, are stored. Consequently when lprof searches for source files, it must assume that the source files are in the current directory. If they are in another directory, you must specify their location with the -I option and a path name.

The following example is a modified version of the previous one that demonstrates the use of -I. As before, assume that the source files are in the directory $HOME/src.

   $ cd $HOME
   $ mybin/a.out
   $ cd doc
   $ lprof -o $HOME/mybin/a.out -c $HOME/a.out.cnt -I $HOME/src

You can specify multiple -I arguments.