LPROF(1) INTERACTIVE UNIX System LPROF(1)
NAME
lprof - display line-by-line execution count profile data
SYNOPSIS
lprof [-p] [-s] [-x] [[-I incdir]] [[-r srcfile]] [-c
cntfile] [-o prog]
lprof -m file1.cnt file2.cnt [[filen.cnt]] [-T] -d
destfile.cnt
DESCRIPTION
lprof is a tool for dynamic analysis; that is, the analysis
of a program at run time. Specifically, lprof identifies
the most frequently executed parts of source code and parts
of code that are never executed.
lprof interprets a profile file (prog.cnt by default) pro-
duced by the profiled program prog (a.out by default) that
has been compiled with the -ql option of cc(1). This cc
command option arranges for code to be inserted to record
run-time behavior and for data to be written to a file at
the end of execution.
By default, lprof prints a listing of source files (the
names of which are stored in the symbol table of the execut-
able file), each line preceded by its line number (in the
file) and the number of times it was executed.
The following options may appear singly or be combined in
any order:
-p Print listing, each line preceded by the line number
and the number of times it was executed (default).
This option can be used together with the -s option to
print both the source listing and summary information.
-s Print summary information of percentage of lines of
code executed per function.
-x Instead of printing the execution count numbers for
each line, print each line preceded by its line number
and a [U] if the line was not executed. If the line
was executed, print only the line number.
-I incdir
Look for source or header files in the directory incdir
in addition to the current directory and the standard
place for #include files (usually /usr/include). You
can specify more than one directory with -I on one com-
mand line.
-r srcfile
Instead of printing all source files, print only those
files named in -r options (to be used with the -p
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LPROF(1) INTERACTIVE UNIX System LPROF(1)
option only). You can specify multiple files with -r
on one command line.
-c cntfile
Use the file cntfile instead of prog.cnt as the input
profile file.
-o prog
Use the name of the program prog instead of the name
used when creating the profile file. Because the pro-
gram name stored in the profile file contains the rela-
tive path, this option is necessary if the executable
file or profile file has been moved.
Merging Data Files
lprof can also be used to merge data files. The -m option
must be accompanied with the -d option:
-m file1.cnt file2.cnt [filen.cnt] -d destfile.cnt
Merge the data files file1.cnt through filen.cnt by
summing the execution counts per line, so that data
from several runs can be accumulated. The result is
written to destfile.cnt. The data files must contain
profiling data for the same prog (see the -T option
below).
-T Time stamp override. Normally, the time stamps of the
executable files being profiled are checked, and data
files will not be merged if the time stamps do not
match. If -T is specified, this check is skipped.
Controlling the Run Time Profiling Environment
The environment variable PROFOPTS provides run time control
over profiling. When a profiled program is about to ter-
minate, it examines the value of PROFOPTS to determine how
the profiling data is to be handled.
The environment variable PROFOPTS is a comma-separated list
of options interpreted by the program being profiled. If
PROFOPTS is not defined in the environment, then the default
action is taken: the profiling data is saved in a file
(with the default name, prog.cnt) in the current directory.
If PROFOPTS is set to the null string, no profiling data is
saved. The following are the available options:
msg=[y|n]
If msg=y is specified, a message stating that profile
data is being saved is printed to stderr. If msg=n is
specified, print only profiling error messages. The
default is msg=y.
merge=[y|n]
If merge=n is specified, do not merge data files after
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LPROF(1) INTERACTIVE UNIX System LPROF(1)
successive runs. The data file is overwritten after
each execution. If merge=y is specified, the data will
be merged. The merge will fail if the program has been
recompiled; the data file will be left in TMPDIR. The
default is merge=n.
pid=[y|n]
If pid=y is specified, the name of the data file will
include the process ID of the profiled program. This
allows the creation of different data files for pro-
grams calling fork(2). If pid=n is specified, the
default name is used. The default is pid=n.
dir=dirname
Place the data file in the directory dirname if this
option is specified. Otherwise, the data file is
created in the directory that is current at the end of
execution.
file=filename
Use filename as the name of the data file in dir
created by the profiled program if this option is
specified. Otherwise, the default name is used.
FILES
prog.cnt for profile data
TMPDIR/* temporary files
TMPDIR is usually /usr/tmp, but can be redefined by setting
the environment variable TMPDIR [see tempnam() in
tmpnam(3S)].
SEE ALSO
cc(1), prof(1), fork(2), tmpnam(3S).
WARNINGS
For the -m option, if destfile.cnt exists, its previous con-
tents are destroyed.
Optimizing functions may result in the loss of some line
number information and may result in code motions, both of
which may make lprof information unreliable.
Different parts of one line of a source file may be executed
different numbers of times (e.g., the for loop below); the
count corresponds to the first part of the line. For exam-
ple, in the following for loop
1 [8] for (j = 0; j < 5; j++)
5 [9] sub(j);
line 8 consists of three parts. The line count listed, how-
ever, is for the initialization part, i.e., j = 0.
lprof incorrectly handles the statement immediately
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LPROF(1) INTERACTIVE UNIX System LPROF(1)
following a for loop containing a single if statement. In
the following example, line 8 is executed only once.
1 [5] for (i = 0; i < 3; i++)
3 [6] if (i > 3)
0 [7] x = i;
3 [8] i = 0;
This problem can be solved by adding curly braces, as fol-
lows:
1 [5] for (i = 0; i < 3; i++) {
3 [6] if (i > 3)
0 [7] x = i;
3 [8] }
1 [9] i = 0;
lprof then handles the statement following the for loop
correctly.
lprof does not provide execution information about case
statements containing only a break statement, or about
return statements without a value.
1 [4] switch (i) {
case 0:
break;
default:
0 [8] i = 0;
}
1 [11] if (i != 0)
return;
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