|GPROF(1)||General Commands Manual||GPROF(1)|
gprof — display
call graph profile data
gprof produces an execution profile of C,
Pascal, or Fortran77 programs. The effect of called routines is incorporated
in the profile of each caller. The profile data is taken from the call graph
profile file (gmon.out default) which is created by
programs that are compiled with the
-pg option of
also links in versions of the library routines that are compiled for
gprof reads the given object file (the
default is a.out) and establishes the relation
between its symbol table and the call graph profile from
gmon.out. If more than one profile file is
gprof output shows the sum of the
profile information in the given profile files.
gprof calculates the amount of time spent
in each routine. Next, these times are propagated along the edges of the
call graph. Cycles are discovered, and calls into a cycle are made to share
the time of the cycle. The first 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 this function's time and the time of
its descendants is 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 and their contributions to the time and call counts of the cycle.
Second, a flat profile is given. This listing gives the total execution times, the call counts, the time in milliseconds the call spent in the routine itself, and the time in milliseconds the call spent in the routine itself including its descendants.
Finally, an index of the function names is provided.
The options are as follows:
gprofto run for a very long time.
-Emcleanup is the default.
-eoption may be given. Only one name may be given with each
-Foption may be given. Only one name may be given with each
-Foption overrides the
-foption may be given. Only one name may be given with each
-koption may be given. Only one pair of routine names may be given with each
gprof(probably also with a
-s) to accumulate profile data across several runs of an a.out file.
-coption for discovering which routines were never called.
S. Graham, P. Kessler, and M. McKusick, An Execution Profiler for Modular Programs, Software - Practice and Experience, 13, pp. 671-685, 1983.
S. Graham, P. Kessler, and M. McKusick, gprof: A Call Graph Execution Profiler, Proceedings of the SIGPLAN '82 Symposium on Compiler Construction, SIGPLAN Notices, 6, 17, pp. 120-126, June 1982.
gprof profiler appeared in
The granularity of the sampling is shown, but remains statistical at best. We assume 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 the function's parents is directly proportional to the number of times that arc is traversed.
Parents that are not themselves profiled will have the time of their profiled children propagated to them, but they will appear to be spontaneously invoked in the call graph listing, and will not have their time propagated further. Similarly, signal catchers, even though profiled, will 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(3) or return normally for the profiling information to be saved in the gmon.out file.
|October 6, 2016||OpenBSD-current|