gprof(1)

NAME

gprof — display call graph profile data

SYNOPSIS

gprof [options] [a.out [gmon.out...]] [shared_library shared_library_profile]

DESCRIPTION

The gprof command produces an execution profile of C++, C, Pascal, and FORTRAN programs. The effect of called routines is incorporated into the profile of each caller. Profile data is taken from the call graph profile file (gmon.out default) that is created by programs compiled with the -G option of aCC, CC, cc, pc, and f77. That option also links in versions of the library routines that are compiled for profiling. The symbol table in the named object file (a.out default) is read and correlated with the call graph profile file. If more than one profile file is specified, gprof output shows the sum of the profile information in the given profile files.

First, a flat profile is given, similar to that provided by prof (see prof(1)). This listing gives the total execution times and call counts for each function in the program, sorted by decreasing time.

Next, these times are propagated along the edges of the call graph. gprof discovers all cycles in the call graph. All calls made into the cycle share the time of that cycle. A second listing shows the functions sorted according to the time they represent including the time of their call graph descendants. Below each function entry is shown its (direct) call graph children, and how their times are propagated to this function. A similar display above the function shows how the time of this function and the time of its descendants are propagated to its (direct) call graph parents.

Cycles are also shown, with an entry for the cycle as a whole and a listing of the members of the cycle, each with their contributions to the time and call counts of the cycle.

Shared Library Profiling (32-bit only)

Support for gprof profiling of shared libraries is available on 32-bit systems only.

To profile shared libraries, set the environment variable LD_PROFILE to the path of the shared library to be profiled. (See HP-UX Linker and Libraries Online User's Guide for details.) Do not use the -G option to compile programs for shared libraries profiling. Do not link the executable gcrt0.o or mcrt0.o. This turns on profiling of a.out, which is not compatible with profiling of shared libraries. You can either profile your executable or a shared library, but not both.

At the termination of the program, a profile file with the name of the shared library prepended to it is generated by a run-time library. To get the complete listing, provide the gprof command with names of the shared library and the profile file for the shared library as arguments.

Options

The gprof command recognizes the following options:

-a: Suppress printing statically declared functions. If this option is given, all relevant information about the static function (such as time samples, calls to other functions, and calls from other functions) belongs to the function loaded just before the static function in the a.out file.
-b: Suppress printing a description of each field in the profile.
-e name: Suppress printing the graph profile entry for routine name and all its descendants (unless they have other ancestors that are not suppressed). More than one -e option can be given. Only one name can be given with each -e option.
-E name: Suppress printing the graph profile entry for routine name (and its descendants) as -e above, and also exclude the time spent in name (and its descendants) from the total and percentage time computations. -E mcount -E mcleanup is the default.
-f name: Print only the graph profile entry of the specified routine name and its descendants. More than one -f option can be given. Only one name can be given with each -f option.
-F name: Print only the graph profile entry of the routine name and its descendants (as -f above) and also use only the times of the printed routines in total time and percentage computations. More than one -F option can be given. Only one name can be given with each -F option. The -F option overrides the -E option.
-s: Produce a profile file gmon.sum that represents the sum of the profile information in all specified profile files. This summary profile file can be given to subsequent executions of gprof (probably also with a -s option) to accumulate profile data across several runs of an a.out file.
-z: Display routines that have zero usage (as indicated by call counts and accumulated time).

The name of the file created by a profiled program is controlled by the environment variable GPROFDIR. If GPROFDIR is not set, gmon.out is produced in the current directory when the program terminates. If GPROFDIR=string, string/pid.progname is produced, where progname consists of argv[0] with any path prefix removed, and pid is the program's process ID. If GPROFDIR is set to a null string, no profiling output is produced.

EXAMPLES

To profile libc.sl:

$ cat > test.c 
main() 
{ 
printf("hello world\n"); 
} 

$ cc test.c -lc 

$ ldd a.out 
        /usr/lib/libc.2 =>      /usr/lib/libc.2
        /usr/lib/libdld.2 =>    /usr/lib/libdld.2
        /usr/lib/libc.2 =>      /usr/lib/libc.2

$ export LD_PROFILE=/usr/lib/libc.2 

$ ./a.out 
hello world

$ unset LD_PROFILE 

$ ls libc.2.profile 
libc.2.profile

$ ll libc.2.profile 
-rw-rw-r--   1 user1       lang        606464 May 19 10:24 libc.2.profile

$ gprof /usr/lib/libc.2 libc.2.profile 

WARNINGS

Beware of quantization errors. The granularity of the sampling is shown, but remains statistical at best. It is assumed that the time for each execution of a function can be expressed by the total time for the function, divided by the number of times the function is called. Thus the time propagated along the call graph arcs to parents of that function is directly proportional to the number of times that arc is traversed.

Parents that are not profiled have the time of their profiled children propagated to them, but they appear to be spontaneously invoked in the call graph listing, and do not have their time propagated further. Similarly, signal catchers, even though profiled, appear to be spontaneous (although for more obscure reasons). Any profiled children of signal catchers should have their times propagated properly unless the signal catcher was invoked during the execution of the profiling routine, in which case all is lost.

The profiled program must call exit() (see exit(2)) or return normally, for the profiling information to be saved in the gmon.out file.

The following limitations exist for gprof shared library profiling:

Local, static, and hidden functions are not profiled.
Shared libraries built with -B symbolic are not profiled.
Any function calls made from library initializers are not collected.

Set LD_PROFILE to the exact string with which you call shl_load. If the library is implicitly loaded, LD_PROFILE must match the path encoded in the a.out. You can find this value by running the ldd command on the executable.

DEPENDENCIES

gprof cannot be used with dynamically linked executables (built with ld -A in pre HP-UX 10.20 releases).

AUTHOR

gprof was developed by the University of California, Berkeley.

FILES

a.out*: Default object file.
gmon.out*: Default dynamic call graph and profile.
gmon.sum*: Summarized dynamic call graph and profile.
/usr/lib/gprof.callg*: Call graph description.
/usr/lib/gprof.flat*: Flat profile description.
/usr/lib/libgprof32.sl: gprof 32-bit shared library profiler