gprof.1

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.\" SCCSID: @(#)gprof.1	8.2	12/4/90
.TH gprof 1 VAX "" Unsupported
\"	@(#)gprof.1	1.9 (Berkeley) 10/12/82
.SH Name
gprof \- display call graph profile data
.SH Syntax
.B gprof
[\|\fIoptions\fR\|] [\|\fIa.out\fR\|[\fIgmon.out...\fR\|]\|]
.SH Description
.NXR "gprof command"
.NXA "cc compiler" "gprof command"
.NXA "pc compiler" "gprof command"
.NXA "f77 compiler" "gprof command"
.NXA "prof command" "gprof command"
.NXAM "monitor subroutine" "gprof command"
.NXAM "profil system call" "gprof command"
.NXR "C program" "displaying call graph profile data and"
.NXR "Pascal program" "displaying call graph profile data and"
.NXR "f77 program" "displaying call graph profile data and"
The
.PN gprof
command 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
which are compiled with the 
.B \-pg
option of 
.PN cc ,
.PN pc ,
and
.PN f77.
That option also links in versions of the library routines 
which 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,
the
.PN gprof
output shows the sum of the profile information
in the given profile files.
.PP
First, a flat profile is given,
similar to that provided by
.MS prof 1 .
This listing gives the total execution times
and call counts for each of the functions
in the program, sorted by decreasing time.
.PP
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.
A second listing shows the functions
sorted according to the time they represent
including the time of their call graph descendents.
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 descendents is propagated to
its (direct) call graph parents.
.PP
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.
.SH Options
.NXR "gprof command" "options"
The following options are available:
.IP \fB\-a\fR 20
Suppresses the printing of statically declared functions.
If this option is given, all relevant information
about the static function
(for example, 
time samples, calls to other functions, calls from other functions)
belongs to the function loaded just before the static function in the
.PN a.out
file.
.IP \fB\-b\fR 20
Suppresses the printing of a description of each field in the profile.
.IP \fB\-c\fR 20
The static call graph of the program is discovered by a heuristic
which examines the text space of the object file.
Static-only parents or children are indicated
with call counts of 0.
.IP "\fB\-\|E\fI name\fR" 20
Suppresses the printing of the graph profile entry for routine
.I name
(and its descendants) as 
.BR \-e ,
above, and also excludes the time spent in
.I name
(and its descendants) from the total and percentage time computations.
(For example,
.B \-E
.I mcount
.B \-E
.I mcleanup
is the default.)
.IP "\fB\-\|e\fI name\fR" 20
Suppresses the printing of the graph profile entry for routine
.I name
and all its descendants
More than one
.B \-e
option may be given.
Only one
.I name
may be given with each
.B \-e
option.
.IP "\fB\-\|F\fI name\fR" 20
Prints the graph profile entry of only the routine
.I name
and its descendants (as 
.BR \-f,
above) and also uses only the times of the printed routines
in total time and percentage computations.
More than one
.B \-F
option may be given.
Only one
.I name
may be given with each
.B \-F
option.
The
.B \-F
option
overrides
the
.B \-E
option.
.IP "\fB\-\|f\fI name\fR" 20
Prints the graph profile entry of only the specified routine
.I name
and its descendants.
More than one
.B \-f
option may be given.
Only one
.I name
may be given with each
.B \-f
option.
.IP \fB\-s\fR 20
Produces a profile file
.I gmon.sum
is produced which represents
the sum of the profile information in all the specified profile files.
This summary profile file may be given to subsequent
executions of gprof (probably also with a
.BR \-s )
to accumulate profile data across several runs of an
.I a.out
file.
.IP \fB\-z\fR 20
Displays routines which have zero usage (as indicated by call counts
and accumulated time).
This is useful in conjunction with the 
.B \-c
option for discovering which routines were never called.
.SH Restrictions
.NXR "gprof command" "restricted"
Beware of quantization errors.
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 parents of that
function is directly proportional to the number of times that
arc is traversed.
.PP
Parents which are not themselves 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.
.PP
The profiled program must call 
.MS exit 2
or return normally for the profiling information to be saved
in the 
.PN gmon.out
file.
.SH Files
.TP 15
.PN a.out	
the name list and text space.
.TP 15
.PN gmon.out	
dynamic call graph and profile.
.TP 15
.PN gmon.sum	
summarized dynamic call graph and profile.
.SH See Also
cc(1), prof(1), profil(2), monitor(3)